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Average Weather in May in Asotin Washington, United States

In Asotin, the month of May is characterized by rising daily high temperatures, with daily highs increasing by 7°F, from 68°F to 75°F over the course of the month, and rarely exceeding 87°F or dropping below 56°F.

Daily low temperatures increase by 7°F, from 46°F to 53°F, rarely falling below 38°F or exceeding 60°F.

For reference, on August 2, the hottest day of the year, temperatures in Asotin typically range from 63°F to 93°F, while on December 22, the coldest day of the year, they range from 30°F to 39°F.

Average High and Low Temperature in May

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 May. 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 May

Average Hourly Temperature in May in Asotin18152229112233445566778899101011111212131314141515161617171818191920202121222223232424252526262727282829293030313112 AM4 AM8 AM12 PM4 PM8 PM12 AMAprJuncoldcoolwarmvery coldcomfortable
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 May in Asotin experiences essentially constant cloud cover, with the percentage of time that the sky is overcast or mostly cloudy remaining about 51% throughout the month.

The clearest day of the month is May 31, with clear, mostly clear, or partly cloudy conditions 50% of the time.

For reference, on January 15, the cloudiest day of the year, the chance of overcast or mostly cloudy conditions is 65%, while on July 29, the clearest day of the year, the chance of clear, mostly clear, or partly cloudy skies is 81%.

Cloud Cover Categories in May

Cloud Cover Categories in May in Asotin1815222911223344556677889910101111121213131414151516161717181819192020212122222323242425252626272728282929303031310%100%10%90%20%80%30%70%40%60%50%50%60%40%70%30%80%20%90%10%100%0%AprJunMay 148%May 148%May 3150%May 3150%May 1149%May 1149%May 2149%May 2149%clearmostly cloudyovercastmostly clearpartly 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 Asotin, the chance of a wet day over the course of May is increasing, starting the month at 24% and ending it at 28%.

For reference, the year's highest daily chance of a wet day is 37% on November 28, and its lowest chance is 7% on August 5.

Probability of Precipitation in May

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 May in Asotin is essentially constant, remaining about 1.7 inches throughout, and rarely exceeding 3.3 inches or falling below 0.6 inches.

The highest average 31-day accumulation is 1.8 inches on May 26.

Average Monthly Rainfall in May

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 May in Asotin, the length of the day is rapidly increasing. From the start to the end of the month, the length of the day increases by 1 hour, 9 minutes, implying an average daily increase of 2 minutes, 17 seconds, and weekly increase of 15 minutes, 59 seconds.

The shortest day of the month is May 1, with 14 hours, 24 minutes of daylight and the longest day is May 31, with 15 hours, 32 minutes of daylight.

Hours of Daylight and Twilight in May

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 latest sunrise of the month in Asotin is 5:33 AM on May 1 and the earliest sunrise is 34 minutes earlier at 5:00 AM on May 31.

The earliest sunset is 7:57 PM on May 1 and the latest sunset is 35 minutes later at 8:32 PM on May 31.

Daylight saving time is observed in Asotin during 2017, but it neither starts nor ends during May, 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 15 hours, 48 minutes later, at 8:44 PM, while on December 21, the shortest day of the year, it rises at 7:28 AM and sets 8 hours, 36 minutes later, at 4:04 PM.

Sunrise & Sunset with Twilight in May

The solar day over the course of May. 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 Asotin is essentially constant during May, remaining around 0% throughout.

For reference, on July 16, 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 May

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 Asotin is essentially constant during May, remaining within 0.2 miles per hour of 6.4 miles per hour throughout.

For reference, on November 19, the windiest day of the year, the daily average wind speed is 7.1 miles per hour, while on August 12, the calmest day of the year, the daily average wind speed is 5.6 miles per hour.

Average Wind Speed in May

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 Asotin throughout May is predominantly from the west, with a peak proportion of 55% on May 31.

Wind Direction in May

Wind Direction in May in Asotin1815222911223344556677889910101111121213131414151516161717181819192020212122222323242425252626272728282929303031310%100%10%90%20%80%30%70%40%60%50%50%60%40%70%30%80%20%90%10%100%0%AprJunsouthwesteastnorth
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 Asotin typically lasts for 7.0 months (216 days), from around March 30 to around November 1, rarely starting before March 2 or after April 23, and rarely ending before October 10 or after November 25.

The month of May in Asotin is very likely fully within the growing season, with the chance that a given day is in the growing season gradually increasing from 96% to 100% over the course of the month.

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

Time Spent in Various Temperature Bands and the Growing Season in May in Asotingrowing season1815222911223344556677889910101111121213131414151516161717181819192020212122222323242425252626272728282929303031310%100%10%90%20%80%30%70%40%60%50%50%60%40%70%30%80%20%90%10%100%0%AprJun96%May 196%May 1100%May 31100%May 31100%May 11100%May 11100%May 21100%May 2190%Apr 2390%Apr 23hotcoldcoolwarmvery coldcomfortable
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 Asotin is increasing during May, increasing by 298°F, from 203°F to 501°F, over the course of the month.

Growing Degree Days in May

The average growing degree days accumulated over the course of May, 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 Asotin is gradually increasing during May, rising by 0.7 kWh, from 5.8 kWh to 6.6 kWh, over the course of the month.

Average Daily Incident Shortwave Solar Energy in May

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 Asotin are 46.339 deg latitude, -117.048 deg longitude, and 1,329 ft elevation.

The topography within 2 miles of Asotin contains very significant variations in elevation, with a maximum elevation change of 1,234 feet and an average elevation above sea level of 1,182 feet. Within 10 miles contains very significant variations in elevation (2,398 feet). Within 50 miles contains large variations in elevation (5,830 feet).

The area within 2 miles of Asotin is covered by grassland (58%) and shrubs (34%), within 10 miles by grassland (44%) and cropland (27%), and within 50 miles by shrubs (34%) and cropland (32%).

Data Sources

This report illustrates the typical weather in Asotin 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 Asotin.

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

The stations contributing to this reconstruction are: Lewiston–Nez Perce County Airport (97%, 4.7 kilometers, northeast); Idaho County Airport (1.2%, 84 kilometers, southeast); and Walla Walla Regional Airport (1.3%, 99 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.

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.