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Climate and Average Weather Year Round at Ronald Reagan Washington National Airport Virginia, United States

At Ronald Reagan Washington National Airport, the summers are hot and muggy, the winters are very cold and snowy, and it is partly cloudy year round. Over the course of the year, the temperature typically varies from 30°F to 88°F and is rarely below 18°F or above 96°F.

Based on the tourism score, the best times of year to visit Ronald Reagan Washington National Airport for warm-weather activities are from early to mid June and from mid August to early October.

Climate at Ronald Reagan Washington National Airport

very coldcoldcoolwarmhotwarmcoolcoldJanFebMarAprMayJunJulAugSepOctNovDecNowNow65%65%48%48%clearovercastprecipitation: 3.5 inprecipitation: 3.5 in2.6 in2.6 inmuggy: 68%muggy: 68%0%0%drydrytourism score: 6.7tourism score: 6.70.30.3
Ronald Reagan Washington National Airport weather by month. Click on each chart for more information.

The hot season lasts for 3.5 months, from May 29 to September 15, with an average daily high temperature above 79°F. The hottest month of the year at Ronald Reagan Washington National Airport is July, with an average high of 88°F and low of 72°F.

The cold season lasts for 3.2 months, from November 29 to March 3, with an average daily high temperature below 52°F. The coldest month of the year at Ronald Reagan Washington National Airport is January, with an average low of 31°F and high of 44°F.

Average High and Low Temperature at Ronald Reagan Washington National Airport

Average High and Low Temperature at Ronald Reagan Washington National AirporthotcoldcoldJanFebMarAprMayJunJulAugSepOctNovDec0°F0°F10°F10°F20°F20°F30°F30°F40°F40°F50°F50°F60°F60°F70°F70°F80°F80°F90°F90°F100°F100°FJan 3044°FJan 3044°FJul 2088°FJul 2088°F30°F30°F73°F73°FMay 2979°FMay 2979°FSep 1579°FSep 1579°FNov 2952°FNov 2952°FMar 352°FMar 352°F63°F63°F65°F65°F39°F39°F36°F36°FNowNow
The daily average high (red line) and low (blue line) temperature, with 25th to 75th and 10th to 90th percentile bands. The thin dotted lines are the corresponding average perceived temperatures.
AverageJanFebMarAprMayJunJulAugSepOctNovDec
High 44°F47°F56°F67°F76°F84°F88°F86°F79°F68°F57°F48°F
Temp. 36°F39°F47°F57°F66°F75°F80°F78°F71°F60°F49°F40°F
Low 31°F32°F40°F49°F59°F68°F72°F71°F64°F53°F43°F35°F

The figure below shows you a compact characterization of the entire year of hourly average temperatures. The horizontal axis is the day of the year, the vertical axis is the hour of the day, and the color is the average temperature for that hour and day.

Average Hourly Temperature at Ronald Reagan Washington National Airport

Average Hourly Temperature at Ronald Reagan Washington National AirportJanFebMarAprMayJunJulAugSepOctNovDec12 AM12 AM2 AM2 AM4 AM4 AM6 AM6 AM8 AM8 AM10 AM10 AM12 PM12 PM2 PM2 PM4 PM4 PM6 PM6 PM8 PM8 PM10 PM10 PM12 AM12 AMNowNowvery coldvery coldcoldcoldcoolcoolcomfortablewarmwarmhotfreezing
frigid 15°F freezing 32°F very cold 45°F cold 55°F cool 65°F comfortable 75°F warm 85°F hot 95°F sweltering
The average hourly temperature, color coded into bands. The shaded overlays indicate night and civil twilight.

Qabaqçöl, Azerbaijan (5,833 miles away) is the far-away foreign place with temperatures most similar to Ronald Reagan Washington National Airport (view comparison).

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At Ronald Reagan Washington National Airport, the average percentage of the sky covered by clouds experiences mild seasonal variation over the course of the year.

The clearer part of the year at Ronald Reagan Washington National Airport begins around July 3 and lasts for 4.3 months, ending around November 13.

The clearest month of the year at Ronald Reagan Washington National Airport is September, during which on average the sky is clear, mostly clear, or partly cloudy 64% of the time.

The cloudier part of the year begins around November 13 and lasts for 7.7 months, ending around July 3.

The cloudiest month of the year at Ronald Reagan Washington National Airport is January, during which on average the sky is overcast or mostly cloudy 51% of the time.

Cloud Cover Categories at Ronald Reagan Washington National Airport

Cloud Cover Categories at Ronald Reagan Washington National AirportclearercloudiercloudierJanFebMarAprMayJunJulAugSepOctNovDec0%100%10%90%20%80%30%70%40%60%50%50%60%40%70%30%80%20%90%10%100%0%Sep 2265%Sep 2265%Jan 548%Jan 548%Jul 356%Jul 356%Nov 1357%Nov 1357%NowNowclearmostly clearpartly cloudymostly cloudyovercast
0% clear 20% mostly clear 40% partly cloudy 60% mostly cloudy 80% overcast 100%
The percentage of time spent in each cloud cover band, categorized by the percentage of the sky covered by clouds.
FractionJanFebMarAprMayJunJulAugSepOctNovDec
Cloudier 51%51%49%48%48%45%41%37%36%37%44%50%
Clearer 49%49%51%52%52%55%59%63%64%63%56%50%

A wet day is one with at least 0.04 inches of liquid or liquid-equivalent precipitation. The chance of wet days at Ronald Reagan Washington National Airport varies throughout the year.

The wetter season lasts 4.4 months, from April 11 to August 24, with a greater than 30% chance of a given day being a wet day. The month with the most wet days at Ronald Reagan Washington National Airport is June, with an average of 11.3 days with at least 0.04 inches of precipitation.

The drier season lasts 7.6 months, from August 24 to April 11. The month with the fewest wet days at Ronald Reagan Washington National Airport is January, with an average of 6.9 days with at least 0.04 inches of precipitation.

Among wet days, we distinguish between those that experience rain alone, snow alone, or a mixture of the two. The month with the most days of rain alone at Ronald Reagan Washington National Airport is June, with an average of 11.3 days. Based on this categorization, the most common form of precipitation throughout the year is rain alone, with a peak probability of 39% on June 16.

Daily Chance of Precipitation at Ronald Reagan Washington National Airport

Daily Chance of Precipitation at Ronald Reagan Washington National AirportwetdrydryJanFebMarAprMayJunJulAugSepOctNovDec0%0%10%10%20%20%30%30%40%40%50%50%60%60%70%70%80%80%90%90%100%100%Jun 1639%Jun 1639%Oct 1920%Oct 1920%Apr 1130%Apr 1130%Aug 2430%Aug 2430%NowNowrainmixedsnow
The percentage of days in which various types of precipitation are observed, excluding trace quantities: rain alone, snow alone, and mixed (both rain and snow fell in the same day).
Days ofJanFebMarAprMayJunJulAugSepOctNovDec
Rain 4.9d5.1d7.5d8.8d10.7d11.3d11.6d10.2d7.7d6.9d6.7d6.1d
Mixed 1.1d1.3d0.5d0.0d0.0d0.0d0.0d0.0d0.0d0.0d0.1d0.7d
Snow 0.9d0.7d0.2d0.0d0.0d0.0d0.0d0.0d0.0d0.0d0.1d0.3d
Any 6.9d7.0d8.2d8.8d10.7d11.3d11.6d10.2d7.7d6.9d6.8d7.2d

To show variation within the months and not just the monthly totals, we show the rainfall accumulated over a sliding 31-day period centered around each day of the year. Ronald Reagan Washington National Airport experiences some seasonal variation in monthly rainfall.

Rain falls throughout the year at Ronald Reagan Washington National Airport. The month with the most rain at Ronald Reagan Washington National Airport is May, with an average rainfall of 3.5 inches.

The month with the least rain at Ronald Reagan Washington National Airport is January, with an average rainfall of 2.1 inches.

Average Monthly Rainfall at Ronald Reagan Washington National Airport

Average Monthly Rainfall at Ronald Reagan Washington National AirportJanFebMarAprMayJunJulAugSepOctNovDec0 in0 in1 in1 in2 in2 in3 in3 in4 in4 in5 in5 in6 in6 in7 in7 inMay 243.5 inMay 243.5 inJan 302.0 inJan 302.0 inSep 283.5 inSep 283.5 inMar 283.3 inMar 283.3 inJul 163.1 inJul 163.1 inNov 283.1 inNov 283.1 inNowNow
The average rainfall (solid line) accumulated over the course of a sliding 31-day period centered on the day in question, with 25th to 75th and 10th to 90th percentile bands. The thin dotted line is the corresponding average snowfall.
JanFebMarAprMayJunJulAugSepOctNovDec
Rainfall 2.1″2.1″3.1″3.3″3.5″3.4″3.1″3.2″3.3″3.3″3.1″2.7″

Snowfall

As with rainfall, we consider the snowfall accumulated over a sliding 31-day period centered around each day of the year. Ronald Reagan Washington National Airport experiences significant seasonal variation in monthly snowfall.

The snowy period of the year lasts for 3.8 months, from November 24 to March 19, with a sliding 31-day snowfall of at least 1.0 inches. The month with the most snow at Ronald Reagan Washington National Airport is February, with an average snowfall of 5.3 inches.

The snowless period of the year lasts for 8.2 months, from March 19 to November 24. The least snow falls around July 14, with an average total accumulation of 0.0 inches.

Average Monthly Snowfall at Ronald Reagan Washington National Airport

Average Monthly Snowfall at Ronald Reagan Washington National AirportsnowsnowJanFebMarAprMayJunJulAugSepOctNovDec0 in0 in5 in5 in10 in10 in15 in15 inJan 305.8 inJan 305.8 inJul 140.0 inJul 140.0 inNov 241.0 inNov 241.0 inMar 191.0 inMar 191.0 in
The average snowfall (solid line) accumulated over the course of a sliding 31-day period centered on the day in question, with 25th to 75th and 10th to 90th percentile bands. The thin dotted line is the corresponding average rainfall.
JanFebMarAprMayJunJulAugSepOctNovDec
Snowfall 4.9″5.3″1.3″0.0″0.0″0.0″0.0″0.0″0.0″0.0″0.5″2.4″

The length of the day at Ronald Reagan Washington National Airport varies significantly over the course of the year. In 2024, the shortest day is December 21, with 9 hours, 27 minutes of daylight; the longest day is June 20, with 14 hours, 54 minutes of daylight.

Hours of Daylight and Twilight at Ronald Reagan Washington National Airport

Hours of Daylight and Twilight at Ronald Reagan Washington National AirportJanFebMarAprMayJunJulAugSepOctNovDec0 hr24 hr4 hr20 hr8 hr16 hr12 hr12 hr16 hr8 hr20 hr4 hr24 hr0 hr12 hr, 7 minMar 1912 hr, 7 minMar 1914 hr, 54 minJun 2014 hr, 54 minJun 2012 hr, 10 minSep 2212 hr, 10 minSep 229 hr, 27 minDec 219 hr, 27 minDec 21nightnightdayNowNow
The number of hours during which the Sun is visible (black line). From bottom (most yellow) to top (most gray), the color bands indicate: full daylight, twilight (civil, nautical, and astronomical), and full night.
Hours ofJanFebMarAprMayJunJulAugSepOctNovDec
Daylight 9.8h10.8h12.0h13.3h14.3h14.8h14.6h13.6h12.4h11.1h10.1h9.5h

The earliest sunrise is at 5:42 AM on June 13, and the latest sunrise is 1 hour, 55 minutes later at 7:36 AM on November 2. The earliest sunset is at 4:46 PM on December 7, and the latest sunset is 3 hours, 51 minutes later at 8:37 PM on June 27.

Daylight saving time (DST) is observed at Ronald Reagan Washington National Airport during 2024, starting in the spring on March 10, lasting 7.8 months, and ending in the fall on November 3.

Sunrise & Sunset with Twilight and Daylight Saving Time at Ronald Reagan Washington National Airport

Sunrise & Sunset with Twilight and Daylight Saving Time at Ronald Reagan Washington National AirportJanFebMarAprMayJunJulAugSepOctNovDec12 AM2 AM4 AM6 AM8 AM10 AM12 PM2 PM4 PM6 PM8 PM10 PM12 AMJun 135:42 AMJun 135:42 AM8:37 PMJun 278:37 PMJun 27Dec 74:46 PMDec 74:46 PM7:36 AMNov 27:36 AMNov 2Mar 10DSTMar 10DSTDSTNov 3DSTNov 3daynightnightnightnightSolarMidnightSolarMidnightSolarNoonSunriseSunset
The solar day over the course of the year 2024. From bottom to top, the black lines are the previous solar midnight, sunrise, solar noon, sunset, and the next solar midnight. The day, twilights (civil, nautical, and astronomical), and night are indicated by the color bands from yellow to gray. The transitions to and from daylight saving time are indicated by the 'DST' labels.

The figure below presents a compact representation of the sun's elevation (the angle of the sun above the horizon) and azimuth (its compass bearing) for every hour of every day in the reporting period. The horizontal axis is the day of the year and the vertical axis is the hour of the day. For a given day and hour of that day, the background color indicates the azimuth of the sun at that moment. The black isolines are contours of constant solar elevation.

Solar Elevation and Azimuth at Ronald Reagan Washington National Airport

Solar Elevation and Azimuth at Ronald Reagan Washington National AirportJanFebMarAprMayJunJulAugSepOctNovDec12 AM12 AM2 AM2 AM4 AM4 AM6 AM6 AM8 AM8 AM10 AM10 AM12 PM12 PM2 PM2 PM4 PM4 PM6 PM6 PM8 PM8 PM10 PM10 PM12 AM12 AM0001010101020202030303040404050506060700001010102020202030304040505060702875NowNow
northeastsouthwest
Solar elevation and azimuth over the course of the year 2024. The black lines are lines of constant solar elevation (the angle of the sun above the horizon, in degrees). The background color fills indicate the azimuth (the compass bearing) of the sun. The lightly tinted areas at the boundaries of the cardinal compass points indicate the implied intermediate directions (northeast, southeast, southwest, and northwest).

The figure below presents a compact representation of key lunar data for 2024. The horizontal axis is the day, the vertical axis is the hour of the day, and the colored areas indicate when the moon is above the horizon. The vertical gray bars (new Moons) and blue bars (full Moons) indicate key Moon phases.

Moon Rise, Set & Phases at Ronald Reagan Washington National Airport

The time in which the moon is above the horizon (light blue area), with new moons (dark gray lines) and full moons (blue lines) indicated. The shaded overlays indicate night and civil twilight.

We base the humidity comfort level on the dew point, as it determines whether perspiration will evaporate from the skin, thereby cooling the body. Lower dew points feel drier and higher dew points feel more humid. Unlike temperature, which typically varies significantly between night and day, dew point tends to change more slowly, so while the temperature may drop at night, a muggy day is typically followed by a muggy night.

Ronald Reagan Washington National Airport experiences extreme seasonal variation in the perceived humidity.

The muggier period of the year lasts for 4.2 months, from May 21 to September 29, during which time the comfort level is muggy, oppressive, or miserable at least 17% of the time. The month with the most muggy days at Ronald Reagan Washington National Airport is July, with 19.8 days that are muggy or worse.

The month with the fewest muggy days at Ronald Reagan Washington National Airport is February, with 0.0 days that are muggy or worse.

Humidity Comfort Levels at Ronald Reagan Washington National Airport

Humidity Comfort Levels at Ronald Reagan Washington National AirportmuggyJanFebMarAprMayJunJulAugSepOctNovDec0%0%10%10%20%20%30%30%40%40%50%50%60%60%70%70%80%80%90%90%100%100%Feb 30%Feb 30%Jul 2768%Jul 2768%May 2117%May 2117%Sep 2917%Sep 2917%NowNowoppressiveoppressivemuggymuggydrydrycomfortablecomfortablemiserablemiserable
dry 55°F comfortable 60°F humid 65°F muggy 70°F oppressive 75°F miserable
The percentage of time spent at various humidity comfort levels, categorized by dew point.
JanFebMarAprMayJunJulAugSepOctNovDec
Muggy days 0.0d0.0d0.0d0.3d4.2d12.9d19.8d18.1d9.2d1.9d0.1d0.0d

This section discusses the wide-area hourly average wind vector (speed and direction) at 10 meters above the ground. The wind experienced at any given location is highly dependent on local topography and other factors, and instantaneous wind speed and direction vary more widely than hourly averages.

The average hourly wind speed at Ronald Reagan Washington National Airport experiences significant seasonal variation over the course of the year.

The windier part of the year lasts for 6.6 months, from October 20 to May 7, with average wind speeds of more than 7.7 miles per hour. The windiest month of the year at Ronald Reagan Washington National Airport is March, with an average hourly wind speed of 9.4 miles per hour.

The calmer time of year lasts for 5.4 months, from May 7 to October 20. The calmest month of the year at Ronald Reagan Washington National Airport is July, with an average hourly wind speed of 5.9 miles per hour.

Average Wind Speed at Ronald Reagan Washington National Airport

Average Wind Speed at Ronald Reagan Washington National AirportwindywindyJanFebMarAprMayJunJulAugSepOctNovDec0 mph0 mph2 mph2 mph4 mph4 mph6 mph6 mph8 mph8 mph10 mph10 mph12 mph12 mph14 mph14 mph16 mph16 mphFeb 269.6 mphFeb 269.6 mphJul 315.7 mphJul 315.7 mphOct 207.7 mphOct 207.7 mphMay 77.7 mphMay 77.7 mphNowNow
The average of mean hourly wind speeds (dark gray line), with 25th to 75th and 10th to 90th percentile bands.
JanFebMarAprMayJunJulAugSepOctNovDec
Wind Speed (mph) 9.09.49.48.67.36.45.96.06.87.68.38.5

The predominant average hourly wind direction at Ronald Reagan Washington National Airport varies throughout the year.

The wind is most often from the north for 3.0 weeks, from March 5 to March 26, with a peak percentage of 32% on March 9. The wind is most often from the west for 4.1 weeks, from March 26 to April 24; for 3.4 weeks, from June 28 to July 22; and for 4.6 months, from October 16 to March 5, with a peak percentage of 35% on July 7. The wind is most often from the south for 2.1 months, from April 24 to June 28 and for 2.8 months, from July 22 to October 16, with a peak percentage of 35% on August 15.

Wind Direction at Ronald Reagan Washington National Airport

Wind Direction at Ronald Reagan Washington National AirportWNWSWSWJanFebMarAprMayJunJulAugSepOctNovDec0%100%20%80%40%60%60%40%80%20%100%0%NowNowwestsouthnortheast
northeastsouthwest
The percentage of hours in which the mean wind direction is from each of the four cardinal wind directions, excluding hours in which the mean wind speed is less than 1.0 mph. The lightly tinted areas at the boundaries are the percentage of hours spent in the implied intermediate directions (northeast, southeast, southwest, and northwest).

Ronald Reagan Washington National Airport is located near a large body of water (e.g., ocean, sea, or large lake). This section reports on the wide-area average surface temperature of that water.

The average water temperature experiences extreme seasonal variation over the course of the year.

The time of year with warmer water lasts for 3.3 months, from June 22 to October 1, with an average temperature above 69°F. The month of the year at Ronald Reagan Washington National Airport with the warmest water is August, with an average temperature of 77°F.

The time of year with cooler water lasts for 3.5 months, from December 19 to April 4, with an average temperature below 44°F. The month of the year at Ronald Reagan Washington National Airport with the coolest water is February, with an average temperature of 36°F.

Average Water Temperature at Ronald Reagan Washington National Airport

Average Water Temperature at Ronald Reagan Washington National AirportwarmcoolJanFebMarAprMayJunJulAugSepOctNovDec30°F30°F40°F40°F50°F50°F60°F60°F70°F70°F80°F80°F90°F90°FAug 977°FAug 977°F36°FFeb 736°FFeb 7Jun 2269°FJun 2269°FOct 169°FOct 169°FDec 1944°FDec 1944°FApr 444°FApr 444°FNowNow
The daily average water temperature (purple line), with 25th to 75th and 10th to 90th percentile bands.
WaterJanFebMarAprMayJunJulAugSepOctNovDec
Temperature 38°F36°F40°F47°F56°F67°F75°F77°F73°F64°F54°F45°F

To characterize how pleasant the weather is at Ronald Reagan Washington National Airport throughout the year, we compute two travel scores.

The tourism score favors clear, rainless days with perceived temperatures between 65°F and 80°F. Based on this score, the best times of year to visit Ronald Reagan Washington National Airport for general outdoor tourist activities are from early to mid June and from mid August to early October, with a peak score in the second week of September.

Tourism Score at Ronald Reagan Washington National Airport

Tourism Score at Ronald Reagan Washington National Airportbest timeJanFebMarAprMayJunJulAugSepOctNovDec002244668810106.76.70.30.36.06.05.45.4NowNowtemperaturetemperature cloudscloudsprecipitationprecipitationtourism score
The tourism score (filled area), and its constituents: the temperature score (red line), the cloud cover score (blue line), and the precipitation score (green line).

The beach/pool score favors clear, rainless days with perceived temperatures between 75°F and 90°F. Based on this score, the best time of year to visit Ronald Reagan Washington National Airport for hot-weather activities is from late June to early September, with a peak score in the second week of August.

Beach/Pool Score at Ronald Reagan Washington National Airport

Beach/Pool Score at Ronald Reagan Washington National Airportbest timeJanFebMarAprMayJunJulAugSepOctNovDec002244668810106.56.50.00.0NowNowtemperaturetemperaturecloudscloudsprecipitationprecipitationbeach/pool score
The beach/pool score (filled area), and its constituents: the temperature score (red line), the cloud cover score (blue line), and the precipitation score (green line).

Methodology

For each hour between 8:00 AM and 9:00 PM of each day in the analysis period (1980 to 2016), independent scores are computed for perceived temperature, cloud cover, and total precipitation. Those scores are combined into a single hourly composite score, which is then aggregated into days, averaged over all the years in the analysis period, and smoothed.

Our cloud cover score is 10 for fully clear skies, falling linearly to 9 for mostly clear skies, and to 1 for fully overcast skies.

Our precipitation score, which is based on the three-hour precipitation centered on the hour in question, is 10 for no precipitation, falling linearly to 9 for trace precipitation, and to 0 for 0.04 inches of precipitation or more.

Our tourism temperature score is 0 for perceived temperatures below 50°F, rising linearly to 9 for 65°F, to 10 for 75°F, falling linearly to 9 for 80°F, and to 1 for 90°F or hotter.

Our beach/pool temperature score is 0 for perceived temperatures below 65°F, rising linearly to 9 for 75°F, to 10 for 82°F, falling linearly to 9 for 90°F, and to 1 for 100°F or hotter.

Definitions of the growing season vary throughout the world, but for the purposes of this report, we define it as the longest continuous period of non-freezing temperatures (≥ 32°F) in the year (the calendar year in the Northern Hemisphere, or from July 1 until June 30 in the Southern Hemisphere).

The growing season at Ronald Reagan Washington National Airport typically lasts for 7.9 months (242 days), from around March 24 to around November 21, rarely starting before March 5 or after April 11, and rarely ending before November 1 or after December 15.

Time Spent in Various Temperature Bands and the Growing Season at Ronald Reagan Washington National Airport

Time Spent in Various Temperature Bands and the Growing Season at Ronald Reagan Washington National Airportgrowing seasonJanFebMarAprMayJunJulAugSepOctNovDec0%100%10%90%20%80%30%70%40%60%50%50%60%40%70%30%80%20%90%10%100%0%50%Mar 2450%Mar 2450%Nov 2150%Nov 2190%Apr 1190%Apr 1190%Nov 190%Nov 110%Mar 510%Mar 510%Dec 1510%Dec 150%Jan 240%Jan 24Jul 21100%Jul 21100%freezingvery coldcoldcoolcomfortablewarmhot
frigid 15°F freezing 32°F very cold 45°F cold 55°F cool 65°F comfortable 75°F warm 85°F hot 95°F sweltering
The percentage of time spent in various temperature bands. The black line is the percentage chance that a given day is within the growing season.

Growing degree days are a measure of yearly heat accumulation used to predict plant and animal development, and defined as the integral of warmth above a base temperature, discarding any excess above a maximum temperature. In this report, we use a base of 50°F and a cap of 86°F.

Based on growing degree days alone, the first spring blooms at Ronald Reagan Washington National Airport should appear around March 18, only rarely appearing before March 3 or after April 3.

Growing Degree Days at Ronald Reagan Washington National Airport

Growing Degree Days at Ronald Reagan Washington National AirportJanFebMarAprMayJunJulAugSepOctNovDec0°F0°F500°F500°F1,000°F1,000°F1,500°F1,500°F2,000°F2,000°F2,500°F2,500°F3,000°F3,000°F3,500°F3,500°F4,000°F4,000°F4,500°F4,500°FMar 1883°FMar 1883°FMay 31900°FMay 31900°FJul 61,800°FJul 61,800°FDec 314,457°FDec 314,457°FNowNow
The average growing degree days accumulated over the course of the year, with 25th to 75th and 10th to 90th percentile bands.

This section discusses the total daily incident shortwave solar energy reaching the surface of the ground over a wide area, taking full account of seasonal variations in the length of the day, the elevation of the Sun above the horizon, and absorption by clouds and other atmospheric constituents. Shortwave radiation includes visible light and ultraviolet radiation.

The average daily incident shortwave solar energy experiences significant seasonal variation over the course of the year.

The brighter period of the year lasts for 3.8 months, from April 27 to August 21, with an average daily incident shortwave energy per square meter above 5.9 kWh. The brightest month of the year at Ronald Reagan Washington National Airport is June, with an average of 6.8 kWh.

The darker period of the year lasts for 3.1 months, from November 5 to February 9, with an average daily incident shortwave energy per square meter below 3.0 kWh. The darkest month of the year at Ronald Reagan Washington National Airport is December, with an average of 2.1 kWh.

Average Daily Incident Shortwave Solar Energy at Ronald Reagan Washington National Airport

Average Daily Incident Shortwave Solar Energy at Ronald Reagan Washington National AirportbrightdarkdarkJanFebMarAprMayJunJulAugSepOctNovDec0 kWh0 kWh1 kWh1 kWh2 kWh2 kWh3 kWh3 kWh4 kWh4 kWh5 kWh5 kWh6 kWh6 kWh7 kWh7 kWh8 kWh8 kWh9 kWh9 kWhJun 226.9 kWhJun 226.9 kWhDec 232.0 kWhDec 232.0 kWhApr 275.9 kWhApr 275.9 kWhAug 215.9 kWhAug 215.9 kWhNov 53.0 kWhNov 53.0 kWhFeb 93.0 kWhFeb 93.0 kWhNowNow
The average daily shortwave solar energy reaching the ground per square meter (orange line), with 25th to 75th and 10th to 90th percentile bands.
JanFebMarAprMayJunJulAugSepOctNovDec
Solar Energy (kWh) 2.33.24.45.56.46.86.76.15.13.82.72.1

For the purposes of this report, the geographical coordinates of Ronald Reagan Washington National Airport are 38.852 deg latitude, -77.037 deg longitude, and 13 ft elevation.

The topography within 2 miles of Ronald Reagan Washington National Airport contains only modest variations in elevation, with a maximum elevation change of 167 feet and an average elevation above sea level of 21 feet. Within 10 miles also contains only modest variations in elevation (476 feet). Within 50 miles contains only modest variations in elevation (1,909 feet).

The area within 2 miles of Ronald Reagan Washington National Airport is covered by artificial surfaces (66%) and water (31%), within 10 miles by artificial surfaces (83%), and within 50 miles by trees (40%) and cropland (22%).

This report illustrates the typical weather at Ronald Reagan Washington National Airport, based on a statistical analysis of historical hourly weather reports and model reconstructions from January 1, 1980 to December 31, 2016.

Temperature and Dew Point

Ronald Reagan Washington National Airport has a weather station that reported reliably enough during the analysis period that we have included it in our network. When available, historical temperature and dew point measurements are taken directly from this weather station. These records are obtained from NOAA's Integrated Surface Hourly data set, falling back on ICAO METAR records as required.

In the case of missing or erroneous measurements from this station, we fall back on records from nearby stations, adjusted according to typical seasonal and diurnal intra-station differences. For a given day of the year and hour of the day, the fallback station is selected to minimize the prediction error over the years for which there are measurements for both stations.

The stations on which we may fall back include but are not limited to Washington Executive Airport/Hyde Field, College Park Airport, Mount Vernon Hospital Heliport, Montgomery County Airpark, Tipton Airport, Washington Dulles International Airport, Quantico Marine Corps Airfield / Turner Field, and Baltimore-Washington International Airport.

Other Data

All data relating to the Sun's position (e.g., sunrise and sunset) are computed using astronomical formulas from the book, Astronomical Algorithms 2nd Edition , by Jean Meeus.

All other weather data, including cloud cover, precipitation, wind speed and direction, and solar flux, come from NASA's MERRA-2 Modern-Era Retrospective Analysis . This reanalysis combines a variety of wide-area measurements in a state-of-the-art global meteorological model to reconstruct the hourly history of weather throughout the world on a 50-kilometer grid.

Land Use data comes from the Global Land Cover SHARE database , published by the Food and Agriculture Organization of the United Nations.

Elevation data comes from the Shuttle Radar Topography Mission (SRTM) , published by NASA's Jet Propulsion Laboratory.

Names, locations, and time zones of places and some airports come from the GeoNames Geographical Database .

Time zones for airports and weather stations are provided by AskGeo.com .

Maps are © OpenStreetMap contributors.

Disclaimer

The information on this site is provided as is, without any assurances as to its accuracy or suitability for any purpose. Weather data is prone to errors, outages, and other defects. We assume no responsibility for any decisions made on the basis of the content presented on this site.

We draw particular cautious attention to our reliance on the MERRA-2 model-based reconstructions for a number of important data series. While having the tremendous advantages of temporal and spatial completeness, these reconstructions: (1) are based on computer models that may have model-based errors, (2) are coarsely sampled on a 50 km grid and are therefore unable to reconstruct the local variations of many microclimates, and (3) have particular difficulty with the weather in some coastal areas, especially small islands.

We further caution that our travel scores are only as good as the data that underpin them, that weather conditions at any given location and time are unpredictable and variable, and that the definition of the scores reflects a particular set of preferences that may not agree with those of any particular reader.

Please review our full terms contained on our Terms of Service page.