Average Weather in July in Chehalis Washington, United States
Daily high temperatures increase by 5°F, from 76°F to 81°F, rarely falling below 66°F or exceeding 92°F.
Daily low temperatures increase by 2°F, from 51°F to 53°F, rarely falling below 45°F or exceeding 59°F.
For reference, on August 4, the hottest day of the year, temperatures in Chehalis typically range from 53°F to 81°F, while on December 20, the coldest day of the year, they range from 35°F to 45°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
The month of July in Chehalis experiences rapidly decreasing cloud cover, with the percentage of time that the sky is overcast or mostly cloudy decreasing from 39% to 23%.
The clearest day of the month is July 30, with clear, mostly clear, or partly cloudy conditions 77% of the time.
For reference, on January 16, the cloudiest day of the year, the chance of overcast or mostly cloudy conditions is 78%, while on August 3, the clearest day of the year, the chance of clear, mostly clear, or partly cloudy skies is 77%.
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 Chehalis, the chance of a wet day over the course of July is very rapidly decreasing, starting the month at 15% and ending it at 7%.
For reference, the year's highest daily chance of a wet day is 60% on November 17, and its lowest chance is 7% on August 3.
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 Chehalis is decreasing, starting the month at 1.1 inches, when it rarely exceeds 2.1 inches or falls below 0.2 inches, and ending the month at 0.5 inches, when it rarely exceeds 1.4 inches.
The lowest average 31-day accumulation is 0.5 inches on July 29.
Average Monthly Rainfall in July
Over the course of July in Chehalis, the length of the day is decreasing. From the start to the end of the month, the length of the day decreases by 53 minutes, implying an average daily decrease of 1 minute, 46 seconds, and weekly decrease of 12 minutes, 21 seconds.
The shortest day of the month is July 31, with 14 hours, 54 minutes of daylight and the longest day is July 1, with 15 hours, 47 minutes of daylight.
Hours of Daylight and Twilight in July
The earliest sunrise of the month in Chehalis is 5:22 AM on July 1 and the latest sunrise is 29 minutes later at 5:50 AM on July 31.
The latest sunset is 9:09 PM on July 1 and the earliest sunset is 24 minutes earlier at 8:44 PM on July 31.
Daylight saving time is observed in Chehalis during 2019, 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 5:18 AM and sets 15 hours, 51 minutes later, at 9:09 PM, while on December 22, the shortest day of the year, it rises at 7:53 AM and sets 8 hours, 33 minutes later, at 4:27 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 Chehalis is essentially constant during July, remaining around 0% throughout.
For reference, on August 7, the muggiest day of the year, there are muggy conditions 1% 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 Chehalis is essentially constant during July, remaining within 0.1 miles per hour of 3.3 miles per hour throughout.
For reference, on December 3, the windiest day of the year, the daily average wind speed is 4.9 miles per hour, while on August 1, the calmest day of the year, the daily average wind speed is 3.2 miles per hour.
Average Wind Speed in July
Wind Direction in July
Chehalis 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 Chehalis is essentially constant during July, remaining around 57°F throughout.
Average Water Temperature 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 Chehalis typically lasts for 6.2 months (190 days), from around April 19 to around October 26, rarely starting before March 27 or after May 9, and rarely ending before October 4 or after November 15.
The month of July in Chehalis is reliably fully within the growing season.
Time Spent in Various Temperature Bands and the Growing Season in July
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 Chehalis are increasing during July, increasing by 423°F, from 658°F to 1,081°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 Chehalis is essentially constant during July, remaining within 0.1 kWh of 6.8 kWh throughout.
The highest average daily incident shortwave solar energy during July is 6.9 kWh on July 21.
Average Daily Incident Shortwave Solar Energy in July
For the purposes of this report, the geographical coordinates of Chehalis are 46.662 deg latitude, -122.964 deg longitude, and 223 ft elevation.
The topography within 2 miles of Chehalis contains significant variations in elevation, with a maximum elevation change of 509 feet and an average elevation above sea level of 256 feet. Within 10 miles contains significant variations in elevation (1,339 feet). Within 50 miles contains very significant variations in elevation (8,284 feet).
The area within 2 miles of Chehalis is covered by cropland (40%), artificial surfaces (28%), shrubs (18%), and trees (15%), within 10 miles by trees (50%) and cropland (27%), and within 50 miles by trees (56%) and shrubs (22%).
This report illustrates the typical weather in Chehalis 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 Chehalis.
For each station, the records are corrected for the elevation difference between that station and Chehalis 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 Chehalis is computed as the weighted average of the individual contributions from each station, with weights proportional to the inverse of the distance between Chehalis and a given station.
The stations contributing to this reconstruction are: Chehalis-Centralia Airport (95%, 2.7 kilometers, northwest); South Lewis County Airport (4.5%, 23 kilometers, southeast); and Clatsop County Airport (0.6%, 90 kilometers, southwest).
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.