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Average Weather in Walla Walla Washington, United States

In Walla Walla, the summers are short, hot, dry, and mostly clear and the winters are chilly and mostly cloudy. Over the course of the year, the temperature typically varies from 30°F to 93°F and is rarely below 17°F or above 102°F.

The hot season lasts for 2.7 months, from June 19 to September 11, with an average daily high temperature above 82°F. The hottest day of the year is July 31, with an average high of 93°F and low of 65°F.

The cold season lasts for 3.3 months, from November 14 to February 22, with an average daily high temperature below 51°F. The coldest day of the year is December 29, with an average low of 30°F and high of 40°F.

Average High and Low Temperature

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 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

Average Hourly Temperature in Walla Walla12 AM4 AM8 AM12 PM4 PM8 PM12 AMJanFebMarAprMayJunJulAugSepOctNovDecchillycoldcoolcomfortablewarmhot
The average hourly temperature, color coded into bands: frigid < 15°F < freezing < 32°F < chilly < 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

In Walla Walla, 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 in Walla Walla begins around June 11 and lasts for 3.9 months, ending around October 8. On July 29, the clearest day of the year, the sky is clear, mostly clear, or partly cloudy 82% of the time, and overcast or mostly cloudy 18% of the time.

The cloudier part of the year begins around October 8 and lasts for 8.1 months, ending around June 11. On January 16, the cloudiest day of the year, the sky is overcast or mostly cloudy 68% of the time, and clear, mostly clear, or partly cloudy 32% of the time.

Cloud Cover

Cloud Cover in Walla Wallaclearercloudiercloudier0%10%20%30%40%50%60%70%80%90%100%JanFebMarAprMayJunJulAugSepOctNovDecJan 1668%Jan 1668%Jul 2918%Jul 2918%Jun 1143%Jun 1143%Oct 844%Oct 844%overcastpartly cloudymostly clearclear
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. The chance of wet days in Walla Walla varies significantly throughout the year.

The wetter season lasts 7.3 months, from October 22 to June 1, with a greater than 22% chance of a given day being a wet day. The chance of a wet day peaks at 37% on November 28.

The drier season lasts 4.7 months, from June 1 to October 22. The smallest chance of a wet day is 7% on August 3.

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 throughout the year is rain alone, with a peak probability of 32% on November 19.

Daily Chance of Precipitation

Daily Chance of Precipitation in Walla Wallawetwetdry0%10%20%30%40%50%60%70%80%90%100%JanFebMarAprMayJunJulAugSepOctNovDecNov 2837%Nov 2837%Aug 37%Aug 37%Oct 2222%Oct 2222%Jun 122%Jun 122%snowrain
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 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. Walla Walla experiences some seasonal variation in monthly rainfall.

The rainy period of the year lasts for 10 months, from September 3 to July 8, with a sliding 31-day rainfall of at least 0.5 inches. The most rain falls during the 31 days centered around November 22, with an average total accumulation of 2.0 inches.

The rainless period of the year lasts for 1.8 months, from July 8 to September 3. The least rain falls around July 30, with an average total accumulation of 0.3 inches.

Average Monthly Rainfall

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.

Snowfall

We report snowfall in liquid-equivalent terms. The actual depth of new snowfall is typically between 5 and 10 times the liquid-equivalent amount, assuming the ground is frozen. Colder, drier snow tends to be on the higher end of that range and warmer, wetter snow on the lower end.

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

The snowy period of the year lasts for 2.8 months, from November 23 to February 18, with a sliding 31-day liquid-equivalent snowfall of at least 0.1 inches. The most snow falls during the 31 days centered around December 30, with an average total liquid-equivalent accumulation of 0.3 inches.

The snowless period of the year lasts for 9.2 months, from February 18 to November 23. The least snow falls around July 14, with an average total liquid-equivalent accumulation of 0.0 inches.

Average Liquid-Equivalent Monthly Snowfall

Average Liquid-Equivalent Monthly Snowfall in Walla Wallasnowsnow0.0 in0.5 in1.0 in1.5 in2.0 inJanFebMarAprMayJunJulAugSepOctNovDecDec 300.3 inDec 300.3 inJul 140.0 inJul 140.0 inFeb 180.1 inFeb 180.1 in
The average liquid-equivalent 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.

Sun

The length of the day in Walla Walla varies significantly over the course of the year. In 2017, the shortest day is December 21, with 8 hours, 38 minutes of daylight; the longest day is June 21, with 15 hours, 46 minutes of daylight.

Hours of Daylight and Twilight

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 is at 5:01 AM on June 15, and the latest sunrise is 2 hours, 37 minutes later at 7:38 AM on November 4. The earliest sunset is at 4:07 PM on December 10, and the latest sunset is 4 hours, 41 minutes later at 8:48 PM on June 25.

Daylight saving time (DST) is observed in Walla Walla during 2017, starting in the spring on March 12, lasting 7.8 months, and ending in the fall on November 5.

Sunrise & Sunset with Twilight and Daylight Saving Time

Sunrise & Sunset with Twilight and Daylight Saving Time in Walla Walla12 AM2 AM4 AM6 AM8 AM10 AM12 PM2 PM4 PM6 PM8 PM10 PM12 AMJanFebMarAprMayJunJulAugSepOctNovDecJun 155:01 AMJun 155:01 AM8:48 PMJun 258:48 PMJun 25Dec 104:07 PMDec 104:07 PM7:38 AMNov 47:38 AMNov 4Mar 12DSTMar 12DSTDSTNov 5DSTNov 5daynightnightnightnight
The solar day over the course of the year 2017. 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.

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 perceived humidity level in Walla Walla, 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

Humidity Comfort Levels in Walla Walla0%10%20%30%40%50%60%70%80%90%100%JanFebMarAprMayJunJulAugSepOctNovDecJan 90%Jan 90%Jul 70%Jul 70%drydryhumidhumidcomfortablecomfortable
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 Walla Walla does not vary significantly over the course of the year, remaining within 0.4 miles per hour of 4.0 miles per hour throughout.

Average Wind Speed

Average Wind Speed in Walla Walla0 mph1 mph2 mph3 mph4 mph5 mph6 mph7 mph8 mphJanFebMarAprMayJunJulAugSepOctNovDecNov 194.5 mphNov 194.5 mphSep 93.6 mphSep 93.6 mph
The average of mean hourly wind speeds (dark gray line), with 25th to 75th and 10th to 90th percentile bands.

The predominant average hourly wind direction in Walla Walla varies throughout the year.

The wind is most often from the west for 6.6 months, from March 18 to October 6, with a peak percentage of 61% on June 23. The wind is most often from the south for 5.4 months, from October 6 to March 18, with a peak percentage of 65% on January 1.

Wind Direction

Wind Direction in Walla WallaSWS0%20%40%60%80%100%JanFebMarAprMayJunJulAugSepOctNovDecwestsoutheastnorth
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).

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 experiences extreme seasonal variation over the course of the year.

The brighter period of the year lasts for 3.1 months, from May 20 to August 23, with an average daily incident shortwave energy per square meter above 6.3 kWh. The brightest day of the year is July 13, with an average of 7.7 kWh.

The darker period of the year lasts for 3.8 months, from October 26 to February 20, with an average daily incident shortwave energy per square meter below 2.5 kWh. The darkest day of the year is December 23, with an average of 1.2 kWh.

Average Daily Incident Shortwave Solar Energy

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 Walla Walla are 46.065 deg latitude, -118.343 deg longitude, and 942 ft elevation.

The topography within 2 miles of Walla Walla contains only modest variations in elevation, with a maximum elevation change of 249 feet and an average elevation above sea level of 942 feet. Within 10 miles contains only modest variations in elevation (3,264 feet). Within 50 miles contains large variations in elevation (6,115 feet).

The area within 2 miles of Walla Walla is covered by artificial surfaces (69%) and cropland (25%), within 10 miles by cropland (78%) and grassland (10%), and within 50 miles by shrubs (39%) and cropland (30%).

Data Sources

This report illustrates the typical weather in Walla Walla, 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 Walla Walla.

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

The stations contributing to this reconstruction are: Walla Walla Regional Airport (89%, 5.5 kilometers, northeast); Eastern Oregon Regional Airport (5%, 57 kilometers, southwest); Meacham, Meacham (2.1%, 62 kilometers, south); and Tri-Cities Airport (4.3%, 64 kilometers, west).

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.