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Climate and Average Weather Year Round at Dillon Airport Montana, United States

At Dillon Airport, the summers are short, warm, dry, and mostly clear and the winters are freezing, snowy, and partly cloudy. Over the course of the year, the temperature typically varies from 13°F to 83°F and is rarely below -7°F or above 90°F.

Based on the tourism score, the best time of year to visit Dillon Airport for warm-weather activities is from early July to mid August.

Climate at Dillon Airport

very coldcoldcoolwarmcoolcoldvery coldJanFebMarAprMayJunJulAugSepOctNovDecNowNow79%79%39%39%clearovercastprecipitation: 2.0 inprecipitation: 2.0 in0.3 in0.3 inmuggy: 0%muggy: 0%0%0%drydrytourism score: 6.1tourism score: 6.10.00.0
Dillon Airport weather by month. Click on each chart for more information.

The warm season lasts for 2.9 months, from June 14 to September 12, with an average daily high temperature above 73°F. The hottest month of the year at Dillon Airport is July, with an average high of 82°F and low of 51°F.

The cold season lasts for 3.4 months, from November 16 to February 26, with an average daily high temperature below 42°F. The coldest month of the year at Dillon Airport is December, with an average low of 14°F and high of 33°F.

Average High and Low Temperature at Dillon Airport

Average High and Low Temperature at Dillon AirportwarmcoldcoldJanFebMarAprMayJunJulAugSepOctNovDec-10°F-10°F0°F0°F10°F10°F20°F20°F30°F30°F40°F40°F50°F50°F60°F60°F70°F70°F80°F80°F90°F90°F100°F100°FDec 2932°FDec 2932°FJul 2583°FJul 2583°F13°F13°F52°F52°FJun 1473°FJun 1473°FSep 1273°FSep 1273°FFeb 2642°FFeb 2642°F45°F45°F43°F43°F23°F23°F21°F21°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 34°F38°F47°F56°F64°F73°F82°F81°F71°F57°F42°F33°F
Temp. 24°F26°F35°F42°F50°F58°F66°F64°F55°F44°F31°F22°F
Low 15°F18°F25°F31°F39°F45°F51°F49°F42°F33°F23°F14°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 Dillon Airport

Average Hourly Temperature at Dillon 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 AMNowNowfreezingfreezingvery coldvery coldcoldcoolcoolcomfortablewarm
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.

Gurgurnica, Macedonia (5,781 miles away); Köse, Turkey (6,293 miles); and Fareydūnshahr, Iran (6,933 miles) are the far-away foreign places with temperatures most similar to Dillon Airport (view comparison).

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At Dillon Airport, the average percentage of the sky covered by clouds experiences significant seasonal variation over the course of the year.

The clearer part of the year at Dillon Airport begins around June 15 and lasts for 3.8 months, ending around October 9.

The clearest month of the year at Dillon Airport is July, during which on average the sky is clear, mostly clear, or partly cloudy 77% of the time.

The cloudier part of the year begins around October 9 and lasts for 8.2 months, ending around June 15.

The cloudiest month of the year at Dillon Airport is March, during which on average the sky is overcast or mostly cloudy 60% of the time.

Cloud Cover Categories at Dillon Airport

Cloud Cover Categories at Dillon AirportclearercloudiercloudierJanFebMarAprMayJunJulAugSepOctNovDec0%100%10%90%20%80%30%70%40%60%50%50%60%40%70%30%80%20%90%10%100%0%Jul 2779%Jul 2779%Mar 1839%Mar 1839%Jun 1559%Jun 1559%Oct 959%Oct 959%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 58%58%60%57%53%40%23%24%33%44%54%57%
Clearer 42%42%40%43%47%60%77%76%67%56%46%43%

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

The wetter season lasts 2.1 months, from April 23 to June 26, with a greater than 21% chance of a given day being a wet day. The month with the most wet days at Dillon Airport is May, with an average of 9.3 days with at least 0.04 inches of precipitation.

The drier season lasts 9.9 months, from June 26 to April 23. The month with the fewest wet days at Dillon Airport is January, with an average of 2.6 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. Based on this categorization, the most common form of precipitation at Dillon Airport changes throughout the year.

Rain alone is the most common for 10 months, from January 25 to December 9. The month with the most days of rain alone at Dillon Airport is May, with an average of 9.0 days.

Snow alone is the most common for 1.5 months, from December 9 to January 25. The month with the most days of snow alone at Dillon Airport is December, with an average of 1.2 days.

Daily Chance of Precipitation at Dillon Airport

Daily Chance of Precipitation at Dillon AirportrainJanFebMarAprMayJunJulAugSepOctNovDec0%0%10%10%20%20%30%30%40%40%50%50%60%60%70%70%80%80%90%90%100%100%May 3035%May 3035%Jan 277%Jan 277%Dec 910%Dec 910%Apr 2321%Apr 2321%NowNowrainsnowmixed
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 0.9d1.2d2.3d4.5d9.0d8.1d5.2d4.7d4.3d3.5d2.2d1.1d
Mixed 0.6d0.6d0.9d1.1d0.3d0.1d0.0d0.0d0.2d0.4d0.7d0.8d
Snow 1.2d0.8d0.7d0.3d0.0d0.0d0.0d0.0d0.0d0.2d0.9d1.2d
Any 2.6d2.6d3.9d5.8d9.3d8.1d5.2d4.7d4.6d4.1d3.8d3.1d

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. Dillon Airport experiences some seasonal variation in monthly rainfall.

The rainy period of the year lasts for 7.0 months, from March 27 to October 28, with a sliding 31-day rainfall of at least 0.5 inches. The month with the most rain at Dillon Airport is May, with an average rainfall of 1.7 inches.

The rainless period of the year lasts for 5.0 months, from October 28 to March 27. The month with the least rain at Dillon Airport is January, with an average rainfall of 0.1 inches.

Average Monthly Rainfall at Dillon Airport

Average Monthly Rainfall at Dillon AirportrainJanFebMarAprMayJunJulAugSepOctNovDec0.0 in0.0 in0.5 in0.5 in1.0 in1.0 in1.5 in1.5 in2.0 in2.0 in2.5 in2.5 in3.0 in3.0 in3.5 in3.5 inMay 292.0 inMay 292.0 inJan 260.1 inJan 260.1 inSep 110.8 inSep 110.8 inMar 270.5 inMar 270.5 inOct 280.5 inOct 280.5 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 0.1″0.2″0.4″0.8″1.7″1.6″0.8″0.7″0.8″0.6″0.3″0.2″

Snowfall

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

The snowy period of the year lasts for 5.7 months, from November 3 to April 25, with a sliding 31-day snowfall of at least 1.0 inches. The month with the most snow at Dillon Airport is December, with an average snowfall of 2.2 inches.

The snowless period of the year lasts for 6.3 months, from April 25 to November 3. The least snow falls around July 18, with an average total accumulation of 0.0 inches.

Average Monthly Snowfall at Dillon Airport

Average Monthly Snowfall at Dillon AirportsnowsnowJanFebMarAprMayJunJulAugSepOctNovDec0 in0 in1 in1 in2 in2 in3 in3 in4 in4 in5 in5 in6 in6 inDec 162.2 inDec 162.2 inJul 180.0 inJul 180.0 inApr 21.6 inApr 21.6 inFeb 51.4 inFeb 51.4 inNov 31.0 inNov 31.0 inNowNow
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 1.7″1.4″1.4″1.4″0.3″0.0″0.0″0.0″0.2″0.6″1.5″2.2″

The length of the day at Dillon Airport varies significantly over the course of the year. In 2024, the shortest day is December 21, with 8 hours, 44 minutes of daylight; the longest day is June 20, with 15 hours, 39 minutes of daylight.

Hours of Daylight and Twilight at Dillon Airport

Hours of Daylight and Twilight at Dillon AirportJanFebMarAprMayJunJulAugSepOctNovDec0 hr24 hr4 hr20 hr8 hr16 hr12 hr12 hr16 hr8 hr20 hr4 hr24 hr0 hr12 hr, 8 minMar 1912 hr, 8 minMar 1915 hr, 39 minJun 2015 hr, 39 minJun 2012 hr, 12 minSep 2212 hr, 12 minSep 228 hr, 44 minDec 218 hr, 44 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 9.2h10.4h12.0h13.6h14.9h15.6h15.2h14.0h12.5h10.9h9.5h8.8h

The earliest sunrise is at 5:41 AM on June 14, and the latest sunrise is 2 hours, 30 minutes later at 8:11 AM on November 2. The earliest sunset is at 4:47 PM on December 9, and the latest sunset is 4 hours, 35 minutes later at 9:22 PM on June 25.

Daylight saving time (DST) is observed at Dillon 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 Dillon Airport

Sunrise & Sunset with Twilight and Daylight Saving Time at Dillon AirportJanFebMarAprMayJunJulAugSepOctNovDec2 AM4 AM6 AM8 AM10 AM12 PM2 PM4 PM6 PM8 PM10 PM12 AMJun 145:41 AMJun 145:41 AM9:22 PMJun 259:22 PMJun 25Dec 94:47 PMDec 94:47 PM8:11 AMNov 28:11 AMNov 2Mar 10DSTMar 10DSTDSTNov 3DSTNov 3daynightnightnightnightSolarMidnightSolarMidnightSolarNoonSunriseSunsetNowNow
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 Dillon Airport

Solar Elevation and Azimuth at Dillon 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 AM000101010102020203030304040506000010101020202020303040405050602168NowNow
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 Dillon 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.

The perceived humidity level at Dillon Airport, as measured by the percentage of time in which the humidity comfort level is muggy, oppressive, or miserable, does not vary significantly over the course of the year, remaining a virtually constant 0% throughout.

Humidity Comfort Levels at Dillon Airport

Humidity Comfort Levels at Dillon AirportJanFebMarAprMayJunJulAugSepOctNovDec0%0%10%10%20%20%30%30%40%40%50%50%60%60%70%70%80%80%90%90%100%100%Jan 260%Jan 260%Jul 270%Jul 270%NowNowdrydry
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 0.0d0.0d0.0d0.0d0.0d0.0d0.0d0.0d0.0d0.0d0.0d0.0d

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 Dillon Airport experiences mild seasonal variation over the course of the year.

The windier part of the year lasts for 6.9 months, from October 16 to May 11, with average wind speeds of more than 6.8 miles per hour. The windiest month of the year at Dillon Airport is December, with an average hourly wind speed of 8.0 miles per hour.

The calmer time of year lasts for 5.1 months, from May 11 to October 16. The calmest month of the year at Dillon Airport is August, with an average hourly wind speed of 5.7 miles per hour.

Average Wind Speed at Dillon Airport

Average Wind Speed at Dillon AirportwindywindyJanFebMarAprMayJunJulAugSepOctNovDec0 mph0 mph2 mph2 mph4 mph4 mph6 mph6 mph8 mph8 mph10 mph10 mph12 mph12 mphNov 308.1 mphNov 308.1 mphAug 35.5 mphAug 35.5 mphOct 166.8 mphOct 166.8 mphMay 116.8 mphMay 116.8 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) 8.07.77.87.46.76.35.75.76.16.87.78.0

The predominant average hourly wind direction at Dillon Airport varies throughout the year.

The wind is most often from the west for 4.9 months, from March 14 to August 11 and for 2.0 months, from August 25 to October 26, with a peak percentage of 43% on October 7. The wind is most often from the south for 2.0 weeks, from August 11 to August 25 and for 4.6 months, from October 26 to March 14, with a peak percentage of 39% on August 20.

Wind Direction at Dillon Airport

Wind Direction at Dillon AirportSWSWSJanFebMarAprMayJunJulAugSepOctNovDec0%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).

To characterize how pleasant the weather is at Dillon 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 time of year to visit Dillon Airport for general outdoor tourist activities is from early July to mid August, with a peak score in the last week of July.

Tourism Score at Dillon Airport

Tourism Score at Dillon Airportbest timeJanFebMarAprMayJunJulAugSepOctNovDec002244668810106.16.10.00.0NowNowtemperaturetemperature 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 Dillon Airport for hot-weather activities is from early July to mid August, with a peak score in the last week of July.

Beach/Pool Score at Dillon Airport

Beach/Pool Score at Dillon AirportJanFebMarAprMayJunJulAugSepOctNovDec002244668810102.92.90.00.0NowNowtemperaturetemperature cloudscloudsprecipitationprecipitation
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 Dillon Airport typically lasts for 3.9 months (121 days), from around May 20 to around September 18, rarely starting before May 3 or after June 10, and rarely ending before September 1 or after October 5.

Time Spent in Various Temperature Bands and the Growing Season at Dillon Airport

Time Spent in Various Temperature Bands and the Growing Season at Dillon Airportgrowing seasonJanFebMarAprMayJunJulAugSepOctNovDec0%100%10%90%20%80%30%70%40%60%50%50%60%40%70%30%80%20%90%10%100%0%May 2050%May 2050%Sep 1850%Sep 1850%Jun 1090%Jun 1090%Sep 190%Sep 190%May 310%May 310%Oct 510%Oct 510%0%Feb 230%Feb 23Jul 22100%Jul 22100%NowNowfrigidfreezingvery 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 Dillon Airport should appear around May 3, only rarely appearing before April 19 or after May 20.

Growing Degree Days at Dillon Airport

Growing Degree Days at Dillon AirportJanFebMarAprMayJunJulAugSepOctNovDec0°F0°F500°F500°F1,000°F1,000°F1,500°F1,500°F2,000°F2,000°FMay 390°FMay 390°FJul 25900°FJul 25900°FDec 311,773°FDec 311,773°F
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 extreme seasonal variation over the course of the year.

The brighter period of the year lasts for 3.0 months, from May 20 to August 19, with an average daily incident shortwave energy per square meter above 6.7 kWh. The brightest month of the year at Dillon Airport is July, with an average of 7.7 kWh.

The darker period of the year lasts for 3.4 months, from October 28 to February 12, with an average daily incident shortwave energy per square meter below 2.9 kWh. The darkest month of the year at Dillon Airport is December, with an average of 1.7 kWh.

Average Daily Incident Shortwave Solar Energy at Dillon Airport

Average Daily Incident Shortwave Solar Energy at Dillon AirportbrightdarkdarkJanFebMarAprMayJunJulAugSepOctNovDec0 kWh0 kWh1 kWh1 kWh2 kWh2 kWh3 kWh3 kWh4 kWh4 kWh5 kWh5 kWh6 kWh6 kWh7 kWh7 kWh8 kWh8 kWh9 kWh9 kWh10 kWh10 kWhJul 27.9 kWhJul 27.9 kWhDec 181.7 kWhDec 181.7 kWhMay 206.7 kWhMay 206.7 kWhAug 196.7 kWhAug 196.7 kWhOct 282.9 kWhOct 282.9 kWhFeb 122.9 kWhFeb 122.9 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) 2.03.14.35.66.67.57.76.85.23.52.21.7

For the purposes of this report, the geographical coordinates of Dillon Airport are 45.255 deg latitude, -112.553 deg longitude, and 5,213 ft elevation.

The topography within 2 miles of Dillon Airport contains only modest variations in elevation, with a maximum elevation change of 377 feet and an average elevation above sea level of 5,151 feet. Within 10 miles contains only modest variations in elevation (3,438 feet). Within 50 miles also contains extreme variations in elevation (6,791 feet).

The area within 2 miles of Dillon Airport is covered by cropland (70%) and grassland (22%), within 10 miles by grassland (45%) and cropland (39%), and within 50 miles by shrubs (32%) and grassland (30%).

This report illustrates the typical weather at Dillon 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

Dillon 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 are Bert Mooney Airport, Lemhi County Airport, Helena Regional Airport, Gallatin Field Airport, Challis Airport, Mission Field, and West Yellowstone.

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.