Average Weather in Ahtanum Washington, United States
In Ahtanum, the summers are warm, dry, and mostly clear and the winters are short, chilly, and partly cloudy. Over the course of the year, the temperature typically varies from 23°F to 89°F and is rarely below 9°F or above 98°F.
The hot season lasts for 3.1 months, from June 12 to September 14, with an average daily high temperature above 78°F. The hottest day of the year is August 1, with an average high of 89°F and low of 56°F.
The cold season lasts for 2.9 months, from November 19 to February 16, with an average daily high temperature below 46°F. The coldest day of the year is December 23, with an average low of 23°F and high of 35°F.
Average High and Low Temperature
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
In Ahtanum, 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 Ahtanum begins around June 7 and lasts for 4.0 months, ending around October 8. On August 3, 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 8.0 months, ending around June 7. On January 16, the cloudiest day of the year, the sky is overcast or mostly cloudy 65% of the time, and clear, mostly clear, or partly cloudy 35% of the time.
A wet day is one with at least 0.04 inches of liquid or liquid-equivalent precipitation. The chance of wet days in Ahtanum varies significantly throughout the year.
The wetter season lasts 5.4 months, from October 19 to March 31, with a greater than 21% chance of a given day being a wet day. The chance of a wet day peaks at 38% on December 1.
The drier season lasts 6.6 months, from March 31 to October 19. The smallest chance of a wet day is 4% on August 4.
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 in Ahtanum changes throughout the year.
Rain alone is the most common for 11 months, from January 7 to December 17. The highest chance of a day with rain alone is 30% on November 9.
Snow alone is the most common for 3.0 weeks, from December 17 to January 7. The highest chance of a day with snow alone is 14% on December 28.
Daily Chance of Precipitation
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. Ahtanum experiences significant seasonal variation in monthly rainfall.
The rainy period of the year lasts for 9.1 months, from September 16 to June 19, with a sliding 31-day rainfall of at least 0.5 inches. The most rain falls during the 31 days centered around November 19, with an average total accumulation of 2.3 inches.
The rainless period of the year lasts for 2.9 months, from June 19 to September 16. The least rain falls around August 5, with an average total accumulation of 0.2 inches.
Average Monthly Rainfall
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. Ahtanum experiences significant seasonal variation in monthly liquid-equivalent snowfall.
The snowy period of the year lasts for 4.4 months, from October 31 to March 13, 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 1.2 inches.
The snowless period of the year lasts for 7.6 months, from March 13 to October 31. The least snow falls around July 5, with an average total liquid-equivalent accumulation of 0.0 inches.
Average Liquid-Equivalent Monthly Snowfall
The length of the day in Ahtanum varies significantly over the course of the year. In 2017, the shortest day is December 21, with 8 hours, 34 minutes of daylight; the longest day is June 21, with 15 hours, 50 minutes of daylight.
Hours of Daylight and Twilight
The earliest sunrise is at 5:08 AM on June 15, and the latest sunrise is 2 hours, 40 minutes later at 7:49 AM on November 4. The earliest sunset is at 4:14 PM on December 10, and the latest sunset is 4 hours, 45 minutes later at 8:59 PM on June 25.
Daylight saving time (DST) is observed in Ahtanum 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
The perceived humidity level in Ahtanum, 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
Average Wind Speed
The predominant average hourly wind direction in Ahtanum is from the west throughout the year.
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 3.3 months, from May 13 to August 21, with an average daily incident shortwave energy per square meter above 6.5 kWh. The brightest day of the year is July 13, with an average of 7.8 kWh.
The darker period of the year lasts for 3.7 months, from October 26 to February 18, with an average daily incident shortwave energy per square meter below 2.6 kWh. The darkest day of the year is December 26, with an average of 1.2 kWh.
Average Daily Incident Shortwave Solar Energy
For the purposes of this report, the geographical coordinates of Ahtanum are 46.560 deg latitude, -120.622 deg longitude, and 1,286 ft elevation.
The topography within 2 miles of Ahtanum contains only modest variations in elevation, with a maximum elevation change of 305 feet and an average elevation above sea level of 1,256 feet. Within 10 miles contains only modest variations in elevation (2,467 feet). Within 50 miles contains large variations in elevation (11,900 feet).
The area within 2 miles of Ahtanum is covered by cropland (86%), within 10 miles by cropland (44%) and shrubs (39%), and within 50 miles by shrubs (55%) and trees (26%).
This report illustrates the typical weather in Ahtanum, 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 Ahtanum.
For each station, the records are corrected for the elevation difference between that station and Ahtanum 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 Ahtanum is computed as the weighted average of the individual contributions from each station, with weights proportional to the inverse of the distance between Ahtanum and a given station.
The stations contributing to this reconstruction are: Yakima Air Terminal Airport (97%, 6 kilometers, east); The Dalles Municipal Airport (2.1%, 113 kilometers, south); and Southwest Washington Regional Airport (1.1%, 181 kilometers, west).
Time zones for aiports and weather stations are provided by AskGeo.com .