Average Weather in July in Grand Coulee Washington, United States
Daily high temperatures increase by 6°F, from 83°F to 90°F, rarely falling below 73°F or exceeding 98°F.
Daily low temperatures increase by 4°F, from 57°F to 61°F, rarely falling below 49°F or exceeding 68°F.
For reference, on July 31, the hottest day of the year, temperatures in Grand Coulee typically range from 61°F to 90°F, while on January 1, the coldest day of the year, they range from 21°F to 30°F.
Average High and Low Temperature in July
The figure below shows you a compact characterization of the hourly average temperatures for the quarter of the year centered on July. 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 July
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
Ivanivka, Ukraine (5,632 miles away); Kemaliye, Turkey (6,262 miles); and Suluktu, Kyrgyzstan (6,349 miles) are the far-away foreign places with temperatures most similar to Grand Coulee (view comparison).
The month of July in Grand Coulee experiences decreasing cloud cover, with the percentage of time that the sky is overcast or mostly cloudy decreasing from 33% to 21%.
The clearest day of the month is July 29, with clear, mostly clear, or partly cloudy conditions 79% of the time.
For reference, on January 15, the cloudiest day of the year, the chance of overcast or mostly cloudy conditions is 70%, while on August 3, the clearest day of the year, the chance of clear, mostly clear, or partly cloudy skies is 79%.
Cloud Cover Categories in July
0% clear 20% mostly clear 40% partly cloudy 60% mostly cloudy 80% overcast 100%
A wet day is one with at least 0.04 inches of liquid or liquid-equivalent precipitation. In Grand Coulee, the chance of a wet day over the course of July is gradually decreasing, starting the month at 9% and ending it at 7%.
For reference, the year's highest daily chance of a wet day is 28% on November 28, and its lowest chance is 5% on August 18.
Probability of Precipitation in July
To show variation within the month and not just the monthly total, we show the rainfall accumulated over a sliding 31-day period centered around each day.
The average sliding 31-day rainfall during July in Grand Coulee is essentially constant, remaining about 0.4 inches throughout, and rarely exceeding 1.3 inches.
Average Monthly Rainfall in July
Over the course of July in Grand Coulee, the length of the day is decreasing. From the start to the end of the month, the length of the day decreases by 56 minutes, implying an average daily decrease of 1 minute, 53 seconds, and weekly decrease of 13 minutes, 10 seconds.
The shortest day of the month is July 31, with 15 hours, 1 minute of daylight and the longest day is July 1, with 15 hours, 58 minutes of daylight.
Hours of Daylight and Twilight in July
The earliest sunrise of the month in Grand Coulee is 5:00 AM on July 1 and the latest sunrise is 30 minutes later at 5:31 AM on July 31.
The latest sunset is 8:58 PM on July 1 and the earliest sunset is 26 minutes earlier at 8:32 PM on July 31.
Daylight saving time is observed in Grand Coulee during 2018, but it neither starts nor ends during July, so the entire month is in daylight saving time.
For reference, on June 21, the longest day of the year, the Sun rises at 4:56 AM and sets 16 hours, 2 minutes later, at 8:59 PM, while on December 21, the shortest day of the year, it rises at 7:42 AM and sets 8 hours, 23 minutes later, at 4:05 PM.
Sunrise & Sunset with Twilight in July
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 Grand Coulee is essentially constant during July, remaining around 0% throughout.
For reference, on July 17, the muggiest day of the year, there are muggy conditions 0% of the time, while on January 1, the least muggy day of the year, there are muggy conditions 0% of the time.
Humidity Comfort Levels in July
dry 55°F comfortable 60°F humid 65°F muggy 70°F oppressive 75°F miserable
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 Grand Coulee is essentially constant during July, remaining within 0.2 miles per hour of 6.2 miles per hour throughout.
For reference, on March 26, the windiest day of the year, the daily average wind speed is 7.1 miles per hour, while on January 5, the calmest day of the year, the daily average wind speed is 6.0 miles per hour.
Average Wind Speed in July
Wind Direction in July
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 Grand Coulee typically lasts for 5.7 months (173 days), from around April 24 to around October 14, rarely starting before April 5 or after May 13, and rarely ending before September 26 or after October 31.
The month of July in Grand Coulee is reliably fully within the growing season.
Time Spent in Various Temperature Bands and the Growing Season in July
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
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 Grand Coulee are rapidly increasing during July, increasing by 669°F, from 918°F to 1,588°F, over the course of the month.
Growing Degree Days in July
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 Grand Coulee is essentially constant during July, remaining within 0.2 kWh of 7.4 kWh throughout.
The highest average daily incident shortwave solar energy during July is 7.6 kWh on July 15.
Average Daily Incident Shortwave Solar Energy in July
For the purposes of this report, the geographical coordinates of Grand Coulee are 47.942 deg latitude, -119.003 deg longitude, and 1,791 ft elevation.
The topography within 2 miles of Grand Coulee contains very significant variations in elevation, with a maximum elevation change of 1,516 feet and an average elevation above sea level of 1,786 feet. Within 10 miles contains very significant variations in elevation (3,451 feet). Within 50 miles also contains extreme variations in elevation (6,204 feet).
The area within 2 miles of Grand Coulee is covered by shrubs (79%) and water (19%), within 10 miles by shrubs (64%) and cropland (17%), and within 50 miles by shrubs (49%) and cropland (17%).
This report illustrates the typical weather in Grand Coulee year round, 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 3 weather stations near enough to contribute to our estimation of the temperature and dew point in Grand Coulee.
For each station, the records are corrected for the elevation difference between that station and Grand Coulee 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 Grand Coulee is computed as the weighted average of the individual contributions from each station, with weights proportional to the inverse of the distance between Grand Coulee and a given station.
The stations contributing to this reconstruction are: Omak Airport (43%, 70 kilometers, northwest); Ephrata Municipal Airport (35%, 80 kilometers, southwest); and Fairchild Air Force Base (23%, 107 kilometers, east).
All data relating to the Sun's position (e.g., sunrise and sunset) are computed using astronomical formulas from the book, Astronomical Tables of the Sun, Moon and Planets , 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 aiports and weather stations are provided by AskGeo.com .
Maps are © Esri, with data from National Geographic, Esri, DeLorme, NAVTEQ, UNEP-WCMC, USGS, NASA, ESA, METI, NRCAN, GEBCO, NOAA, and iPC.
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.