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Summer Weather in Frederick Maryland, United States

Daily high temperatures are around 85°F, rarely falling below 70°F or exceeding 97°F. The highest daily average high temperature is 89°F on July 20.

Daily low temperatures increase by 4°F, from 58°F to 61°F, rarely falling below 47°F or exceeding 73°F. The highest daily average low temperature is 67°F on July 21.

For reference, on July 20, the hottest day of the year, temperatures in Frederick typically range from 67°F to 89°F, while on January 30, the coldest day of the year, they range from 24°F to 42°F.

Average High and Low Temperature in the Summer in Frederick

Average High and Low Temperature in the Summer in FrederickJunJulAug40°F40°F50°F50°F60°F60°F70°F70°F80°F80°F90°F90°F100°F100°FSpringFallJul 2089°FJul 2089°F67°F67°FJun 181°FJun 181°F58°F58°FAug 3185°FAug 3185°F61°F61°FJul 188°FJul 188°F65°F65°FAug 189°FAug 189°F66°F66°F
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.

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

Average Hourly Temperature in the Summer in Frederick

Average Hourly Temperature in the Summer in FrederickJunJulAug12 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 AMSpringFallcoldcoolcoolcoolcoolcomfortablewarmhotcold
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.

Bojnūrd, Iran (6,405 miles away) is the far-away foreign place with temperatures most similar to Frederick (view comparison).

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The summer in Frederick experiences rapidly decreasing cloud cover, with the percentage of time that the sky is overcast or mostly cloudy decreasing from 48% to 35%.

The clearest day of the summer is August 28, with clear, mostly clear, or partly cloudy conditions 66% of the time.

For reference, on January 11, the cloudiest day of the year, the chance of overcast or mostly cloudy conditions is 53%, while on September 3, the clearest day of the year, the chance of clear, mostly clear, or partly cloudy skies is 66%.

Cloud Cover Categories in the Summer in Frederick

Cloud Cover Categories in the Summer in FrederickJunJulAug0%100%10%90%20%80%30%70%40%60%50%50%60%40%70%30%80%20%90%10%100%0%SpringFallJun 152%Jun 152%Aug 3165%Aug 3165%Jul 157%Jul 157%Aug 162%Aug 162%clearmostly 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.

A wet day is one with at least 0.04 inches of liquid or liquid-equivalent precipitation. In Frederick, the chance of a wet day over the course of the summer is very rapidly decreasing, starting the season at 38% and ending it at 28%.

For reference, the year's highest daily chance of a wet day is 39% on June 16, and its lowest chance is 20% on October 19.

Probability of Precipitation in the Summer in Frederick

Probability of Precipitation in the Summer in FrederickJunJulAug0%0%5%5%10%10%15%15%20%20%25%25%30%30%35%35%40%40%SpringFallJun 1639%Jun 1639%Jun 138%Jun 138%Aug 3128%Aug 3128%Jul 136%Jul 136%Aug 136%Aug 136%rain
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).

Rainfall

To show variation within the season and not just the monthly totals, we show the rainfall accumulated over a sliding 31-day period centered around each day.

The average sliding 31-day rainfall during the summer in Frederick is gradually decreasing, starting the season at 3.5 inches, when it rarely exceeds 5.7 inches or falls below 1.5 inches, and ending the season at 3.0 inches, when it rarely exceeds 6.0 inches or falls below 1.0 inches.

The lowest average 31-day accumulation is 2.9 inches on August 6.

Average Monthly Rainfall in the Summer in Frederick

Average Monthly Rainfall in the Summer in FrederickJunJulAug0 in0 in1 in1 in2 in2 in3 in3 in4 in4 in5 in5 in6 in6 in7 in7 inSpringFallAug 62.9 inAug 62.9 inJun 13.5 inJun 13.5 inAug 313.0 inAug 313.0 inJul 13.1 inJul 13.1 in
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.

Over the course of the summer in Frederick, the length of the day is rapidly decreasing. From the start to the end of the season, the length of the day decreases by 1 hour, 43 minutes, implying an average daily decrease of 1 minute, 8 seconds, and weekly decrease of 7 minutes, 56 seconds.

The shortest day of the summer is August 31, with 13 hours, 4 minutes of daylight and the longest day is June 20, with 14 hours, 57 minutes of daylight.

Hours of Daylight and Twilight in the Summer in Frederick

Hours of Daylight and Twilight in the Summer in FrederickJunJulAug0 hr24 hr4 hr20 hr8 hr16 hr12 hr12 hr16 hr8 hr20 hr4 hr24 hr0 hrSpringFallJun 2014 hr, 57 minJun 2014 hr, 57 minnightnightdaydayAug 3113 hr, 4 minAug 3113 hr, 4 minAug 114 hr, 11 minAug 114 hr, 11 min
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.

The earliest sunrise of the summer in Frederick is 5:42 AM on June 14 and the latest sunrise is 56 minutes later at 6:37 AM on August 31.

The latest sunset is 8:40 PM on June 27 and the earliest sunset is 1 hour, 0 minutes earlier at 7:41 PM on August 31.

Daylight saving time is observed in Frederick during 2024, but it neither starts nor ends during the summer, so the entire season is in daylight saving time.

For reference, on June 20, the longest day of the year, the Sun rises at 5:42 AM and sets 14 hours, 57 minutes later, at 8:40 PM, while on December 21, the shortest day of the year, it rises at 7:26 AM and sets 9 hours, 23 minutes later, at 4:49 PM.

Sunrise & Sunset with Twilight in the Summer in Frederick

Sunrise & Sunset with Twilight in the Summer in FrederickJunJulAug2 AM4 AM6 AM8 AM10 AM12 PM2 PM4 PM6 PM8 PM10 PM12 AMSpringFall5:42 AM5:42 AMJun 148:38 PMJun 148:38 PM6:37 AM6:37 AMAug 317:41 PMAug 317:41 PM5:46 AM5:46 AMJul 18:40 PMJul 18:40 PM6:09 AM6:09 AMAug 18:21 PMAug 18:21 PMSolarMidnightSolarMidnightSolarNoonSunriseSunset
The solar day in the summer. 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 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 in the Summer in Frederick

Solar Elevation and Azimuth in the Summer in FrederickJunJulAug12 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 AMSpringFall00102020303040505060607000101020303040405060
northeastsouthwest
Solar elevation and azimuth in the the summer of 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 the summer of 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. The label associated with each bar indicates the date and time that the phase is obtained, and the companion time labels indicate the rise and set times of the Moon for the nearest time interval in which the moon is above the horizon.

Moon Rise, Set & Phases in the Summer in Frederick

Moon Rise, Set & Phases in the Summer in FrederickJunJulAug12 AM12 AM4 AM4 AM8 AM8 AM12 PM12 PM4 PM4 PM8 PM8 PM12 AM12 AMSpringFallMay 711:23 PMMay 711:23 PMMay 239:54 AMMay 239:54 AMJun 68:38 AMJun 68:38 AMJun 219:09 PMJun 219:09 PMJul 56:58 PMJul 56:58 PMJul 216:18 AMJul 216:18 AMAug 47:14 AMAug 47:14 AMAug 192:26 PMAug 192:26 PMSep 29:56 PMSep 29:56 PMSep 1710:35 PMSep 1710:35 PM5:29 AM5:29 AM8:01 PM8:01 PM7:53 PM7:53 PM5:28 AM5:28 AM5:19 AM5:19 AM9:20 PM9:20 PM8:56 PM8:56 PM5:47 AM5:47 AM9:02 PM9:02 PM8:32 PM8:32 PM5:48 AM5:48 AM6:03 AM6:03 AM8:50 PM8:50 PM8:17 PM8:17 PM7:17 AM7:17 AM7:42 PM7:42 PM7:10 PM7:10 PM7:23 AM7:23 AM
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 chance that a given day will be muggy in Frederick is rapidly increasing during the summer, rising from 29% to 39% over the course of the season.

The highest chance of a muggy day during the summer is 64% on July 27.

For reference, on July 27, the muggiest day of the year, there are muggy conditions 64% of the time, while on January 30, the least muggy day of the year, there are muggy conditions 0% of the time.

Humidity Comfort Levels in the Summer in Frederick

Humidity Comfort Levels in the Summer in FrederickJunJulAug0%0%10%10%20%20%30%30%40%40%50%50%60%60%70%70%80%80%90%90%100%100%SpringFallJul 2764%Jul 2764%Jun 129%Jun 129%Aug 3139%Aug 3139%Jul 153%Jul 153%oppressiveoppressivemuggymuggyhumidhumiddrydrycomfortablecomfortablemiserablemiserable
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.

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 in Frederick is gradually decreasing during the summer, decreasing from 6.6 miles per hour to 6.1 miles per hour over the course of the season.

For reference, on February 26, the windiest day of the year, the daily average wind speed is 9.5 miles per hour, while on July 31, the calmest day of the year, the daily average wind speed is 5.6 miles per hour.

The lowest daily average wind speed during the summer is 5.6 miles per hour on July 31.

Average Wind Speed in the Summer in Frederick

Average Wind Speed in the Summer in FrederickJunJulAug0 mph0 mph2 mph2 mph4 mph4 mph6 mph6 mph8 mph8 mph10 mph10 mph12 mph12 mphSpringFallJul 315.6 mphJul 315.6 mphJun 16.6 mphJun 16.6 mphAug 316.1 mphAug 316.1 mphJul 16.1 mphJul 16.1 mph
The average of mean hourly wind speeds (dark gray line), with 25th to 75th and 10th to 90th percentile bands.

The wind direction in Frederick during the summer is predominantly out of the west from June 1 to July 30 and the south from July 30 to August 31.

Wind Direction in the Summer in Frederick

Wind Direction in the Summer in FrederickWSJunJulAug0%100%20%80%40%60%60%40%80%20%100%0%SpringFallwestsouthnortheast
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).

Frederick 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 surface water temperature in Frederick is very rapidly increasing during the summer, rising by 14°F, from 62°F to 75°F, over the course of the season.

The highest average surface water temperature during the summer is 77°F on August 11.

Average Water Temperature in the Summer in Frederick

Average Water Temperature in the Summer in FrederickJunJulAug45°F45°F50°F50°F55°F55°F60°F60°F65°F65°F70°F70°F75°F75°F80°F80°F85°F85°FSpringFallAug 1177°FAug 1177°FJun 162°FJun 162°FAug 3175°FAug 3175°FJul 171°FJul 171°F
The daily average water temperature (purple line), with 25th to 75th and 10th to 90th percentile bands.

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 in Frederick typically lasts for 6.2 months (190 days), from around April 14 to around October 22, rarely starting before March 28 or after May 3, and rarely ending before October 3 or after November 9.

The summer in Frederick is reliably fully within the growing season.

Time Spent in Various Temperature Bands and the Growing Season in the Summer in Frederick

Time Spent in Various Temperature Bands and the Growing Season in the Summer in Frederickgrowing seasonJunJulAug0%100%10%90%20%80%30%70%40%60%50%50%60%40%70%30%80%20%90%10%100%0%SpringFall100%Jul 17100%Jul 1790%May 390%May 3coldcoolcomfortablewarmhotvery cold
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.

The average accumulated growing degree days in Frederick are very rapidly increasing during the summer, increasing by 2,201°F, from 796°F to 2,997°F, over the course of the season.

Growing Degree Days in the Summer in Frederick

Growing Degree Days in the Summer in FrederickJunJulAug1,000°F1,000°F1,500°F1,500°F2,000°F2,000°F2,500°F2,500°F3,000°F3,000°FSpringFallJun 1796°FJun 1796°FAug 312,997°FAug 312,997°FJul 11,468°FJul 11,468°FAug 12,273°FAug 12,273°F
The average growing degree days accumulated over the course of the summer, 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 in Frederick is gradually decreasing during the summer, falling by 0.9 kWh, from 6.7 kWh to 5.7 kWh, over the course of the season.

The highest average daily incident shortwave solar energy during the summer is 7.0 kWh on June 22.

Average Daily Incident Shortwave Solar Energy in the Summer in Frederick

Average Daily Incident Shortwave Solar Energy in the Summer in FrederickJunJulAug0 kWh0 kWh1 kWh1 kWh2 kWh2 kWh3 kWh3 kWh4 kWh4 kWh5 kWh5 kWh6 kWh6 kWh7 kWh7 kWh8 kWh8 kWh9 kWh9 kWhSpringFallJun 227.0 kWhJun 227.0 kWhJun 16.7 kWhJun 16.7 kWhAug 315.7 kWhAug 315.7 kWhAug 16.5 kWhAug 16.5 kWh
The average daily shortwave solar energy reaching the ground per square meter (orange line), with 25th to 75th and 10th to 90th percentile bands.

For the purposes of this report, the geographical coordinates of Frederick are 39.414 deg latitude, -77.411 deg longitude, and 282 ft elevation.

The topography within 2 miles of Frederick contains only modest variations in elevation, with a maximum elevation change of 243 feet and an average elevation above sea level of 311 feet. Within 10 miles contains only modest variations in elevation (1,539 feet). Within 50 miles contains very significant variations in elevation (2,487 feet).

The area within 2 miles of Frederick is covered by artificial surfaces (91%), within 10 miles by cropland (62%) and trees (26%), and within 50 miles by cropland (44%) and trees (38%).

This report illustrates the typical weather in Frederick, 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

There are 4 weather stations near enough to contribute to our estimation of the temperature and dew point in Frederick.

For each station, the records are corrected for the elevation difference between that station and Frederick according to the International Standard Atmosphere , and by the relative change present in the MERRA-2 satellite-era reanalysis between the two locations.

The estimated value at Frederick is computed as the weighted average of the individual contributions from each station, with weights proportional to the inverse of the distance between Frederick and a given station.

The stations contributing to this reconstruction are:

To get a sense of how much these sources agree with each other, you can view a comparison of Frederick and the stations that contribute to our estimates of its temperature history and climate. Please note that each source's contribution is adjusted for elevation and the relative change present in the MERRA-2 data.

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.

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