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Average Weather in August in Zillah Washington, United States

In Zillah, the month of August is characterized by falling daily high temperatures, with daily highs decreasing by 7°F, from 92°F to 86°F over the course of the month, and rarely exceeding 101°F or dropping below 76°F.

Daily low temperatures decrease by 6°F, from 60°F to 54°F, rarely falling below 47°F or exceeding 68°F.

For reference, on July 30, the hottest day of the year, temperatures in Zillah typically range from 60°F to 92°F, while on December 23, the coldest day of the year, they range from 25°F to 36°F.

Average High and Low Temperature in August

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 temperatures for the quarter of the year centered on August. 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 August

Average Hourly Temperature in August in Zillah18152229112233445566778899101011111212131314141515161617171818191920202121222223232424252526262727282829293030313112 AM4 AM8 AM12 PM4 PM8 PM12 AMJulSepcoldwarmhotcoolcomfortable
The average hourly temperature, color coded into bands: 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 shaded overlays indicate night and civil twilight.

Clouds

The month of August in Zillah experiences increasing cloud cover, with the percentage of time that the sky is overcast or mostly cloudy increasing from 18% to 26%. The lowest chance of overcast or mostly cloudy conditions is 17% on August 4.

The clearest day of the month is August 4, with clear, mostly clear, or partly cloudy conditions 83% of the time.

For reference, on January 16, the cloudiest day of the year, the chance of overcast or mostly cloudy conditions is 65%, while on August 4, the clearest day of the year, the chance of clear, mostly clear, or partly cloudy skies is 83%.

Cloud Cover Categories in August

Cloud Cover Categories in August in Zillah1815222911223344556677889910101111121213131414151516161717181819192020212122222323242425252626272728282929303031310%100%10%90%20%80%30%70%40%60%50%50%60%40%70%30%80%20%90%10%100%0%JulSepJan 1635%Jan 1635%Aug 182%Aug 182%Aug 3174%Aug 3174%Aug 1180%Aug 1180%Aug 2176%Aug 2176%clearovercastmostly clearmostly cloudypartly cloudy
The percentage of time spent in each cloud cover band, categorized by the percentage of the sky covered by clouds: clear < 20% < mostly clear < 40% < partly cloudy < 60% < mostly cloudy < 80% < overcast.

Precipitation

A wet day is one with at least 0.04 inches of liquid or liquid-equivalent precipitation. In Zillah, the chance of a wet day over the course of August is essentially constant, remaining around 4% throughout.

For reference, the year's highest daily chance of a wet day is 29% on November 28, and its lowest chance is 3% on August 16.

Probability of Precipitation in August

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 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 August in Zillah is essentially constant, remaining about 0.2 inches throughout, and rarely exceeding 0.7 inches.

The lowest average 31-day accumulation is 0.1 inches on August 6.

Average Monthly Rainfall in August

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 liquid-equivalent snowfall.

Sun

Over the course of August in Zillah, the length of the day is rapidly decreasing. From the start to the end of the month, the length of the day decreases by 1 hour, 28 minutes, implying an average daily decrease of 2 minutes, 56 seconds, and weekly decrease of 20 minutes, 30 seconds.

The shortest day of the month is August 31, with 13 hours, 21 minutes of daylight and the longest day is August 1, with 14 hours, 48 minutes of daylight.

Hours of Daylight and Twilight in August

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 month in Zillah is 5:42 AM on August 1 and the latest sunrise is 38 minutes later at 6:20 AM on August 31.

The latest sunset is 8:31 PM on August 1 and the earliest sunset is 50 minutes earlier at 7:41 PM on August 31.

Daylight saving time is observed in Zillah during 2017, but it neither starts nor ends during August, so the entire month is in daylight saving time.

For reference, on June 21, the longest day of the year, the Sun rises at 5:08 AM and sets 15 hours, 49 minutes later, at 8:57 PM, while on December 21, the shortest day of the year, it rises at 7:41 AM and sets 8 hours, 35 minutes later, at 4:17 PM.

Sunrise & Sunset with Twilight in August

The solar day over the course of August. 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.

Humidity

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 Zillah is essentially constant during August, remaining around 0% throughout.

For reference, on July 15, 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 August

The percentage of time spent at various humidity comfort levels, categorized by dew point: dry < 55°F < comfortable < 60°F < humid < 65°F < muggy < 70°F < oppressive < 75°F < miserable.

Wind

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 Zillah is essentially constant during August, remaining within 0.2 miles per hour of 7.0 miles per hour throughout.

For reference, on March 31, the windiest day of the year, the daily average wind speed is 8.0 miles per hour, while on December 20, the calmest day of the year, the daily average wind speed is 6.7 miles per hour.

Average Wind Speed in August

The average of mean hourly wind speeds (dark gray line), with 25th to 75th and 10th to 90th percentile bands.
The hourly average wind direction in Zillah throughout August is predominantly from the west, with a peak proportion of 65% on August 2.

Wind Direction in August

Wind Direction in August in Zillah1815222911223344556677889910101111121213131414151516161717181819192020212122222323242425252626272728282929303031310%100%10%90%20%80%30%70%40%60%50%50%60%40%70%30%80%20%90%10%100%0%JulSepwestnortheastsouth
The percentage of hours in which the mean wind direction is from each of the four cardinal wind directions (north, east, south, and west), excluding hours in which the mean wind speed is less than 1 mph. The lightly tinted areas at the boundaries are the percentage of hours spent in the implied intermediate directions (northeast, southeast, southwest, and northwest).

Growing Season

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 Zillah typically lasts for 5.9 months (180 days), from around April 18 to around October 16, rarely starting before March 31 or after May 7, and rarely ending before September 28 or after November 2.

The month of August in Zillah is reliably fully within the growing season.

Time Spent in Various Temperature Bands and the Growing Season in August

Time Spent in Various Temperature Bands and the Growing Season in August in Zillahgrowing season1815222911223344556677889910101111121213131414151516161717181819192020212122222323242425252626272728282929303031310%100%10%90%20%80%30%70%40%60%50%50%60%40%70%30%80%20%90%10%100%0%JulSep100%Aug 16100%Aug 1690%Sep 2890%Sep 28Jul 18100%Jul 18100%coolwarmhotcoldcomfortablevery coldsweltering
The percentage of time spent in various temperature bands: 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 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 Zillah is rapidly increasing during August, increasing by 677°F, from 1,881°F to 2,558°F, over the course of the month.

Growing Degree Days in August

The average growing degree days accumulated over the course of August, with 25th to 75th and 10th to 90th percentile bands.

Solar Energy

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 Zillah is decreasing during August, falling by 1.4 kWh, from 7.4 kWh to 6.0 kWh, over the course of the month.

Average Daily Incident Shortwave Solar Energy in August

The average daily shortwave solar energy reaching the ground per square meter (orange line), with 25th to 75th and 10th to 90th percentile bands.

Topography

For the purposes of this report, the geographical coordinates of Zillah are 46.402 deg latitude, -120.262 deg longitude, and 801 ft elevation.

The topography within 2 miles of Zillah contains only modest variations in elevation, with a maximum elevation change of 318 feet and an average elevation above sea level of 813 feet. Within 10 miles contains only modest variations in elevation (2,405 feet). Within 50 miles contains large variations in elevation (6,709 feet).

The area within 2 miles of Zillah is covered by cropland (76%) and artificial surfaces (22%), within 10 miles by cropland (59%) and shrubs (28%), and within 50 miles by shrubs (63%) and cropland (20%).

Data Sources

This report illustrates the typical weather in Zillah 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 4 weather stations near enough to contribute to our estimation of the temperature and dew point in Zillah.

For each station, the records are corrected for the elevation difference between that station and Zillah 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 Zillah is computed as the weighted average of the individual contributions from each station, with weights proportional to the inverse of the distance between Zillah and a given station.

The stations contributing to this reconstruction are: Yakima Air Terminal Airport (59%, 28 kilometers, northwest); Hanford (24%, 54 kilometers, east); Hermiston Municipal Airport (9%, 100 kilometers, southeast); and The Dalles Municipal Airport (8%, 112 kilometers, southwest).

Other Data

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.

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.