Average Weather in McChord Air Force Base Washington, United States
In McChord Air Force Base, the summers are short, warm, dry, and partly cloudy and the winters are very cold, wet, and overcast. Over the course of the year, the temperature typically varies from 34°F to 79°F and is rarely below 23°F or above 89°F.
Based on the tourism score, the best time of year to visit McChord Air Force Base for warm-weather activities is from mid July to late August.
The warm season lasts for 2.7 months, from June 23 to September 15, with an average daily high temperature above 72°F. The hottest day of the year is August 3, with an average high of 79°F and low of 55°F.
The cool season lasts for 3.5 months, from November 13 to February 26, with an average daily high temperature below 52°F. The coldest day of the year is January 1, with an average low of 34°F and high of 45°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 McChord Air Force Base, the average percentage of the sky covered by clouds experiences extreme seasonal variation over the course of the year.
The clearer part of the year in McChord Air Force Base begins around June 13 and lasts for 3.8 months, ending around October 7. On August 3, the clearest day of the year, the sky is clear, mostly clear, or partly cloudy 77% of the time, and overcast or mostly cloudy 23% of the time.
The cloudier part of the year begins around October 7 and lasts for 8.2 months, ending around June 13. On January 16, the cloudiest day of the year, the sky is overcast or mostly cloudy 75% of the time, and clear, mostly clear, or partly cloudy 25% of the time.
Cloud Cover Categories
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. The chance of wet days in McChord Air Force Base varies very significantly throughout the year.
The wetter season lasts 6.8 months, from October 9 to May 2, with a greater than 32% chance of a given day being a wet day. The chance of a wet day peaks at 58% on November 18.
The drier season lasts 5.2 months, from May 2 to October 9. The smallest chance of a wet day is 7% on August 5.
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 56% on November 18.
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. McChord Air Force Base experiences extreme seasonal variation in monthly rainfall.
Rain falls throughout the year in McChord Air Force Base. The most rain falls during the 31 days centered around November 22, with an average total accumulation of 8.3 inches.
The least rain falls around July 30, with an average total accumulation of 0.5 inches.
Average Monthly Rainfall
The sliding 31-day liquid-equivalent quantity of snowfall in McChord Air Force Base does not vary significantly over the course of the year, staying within 0.1 inches of 0.1 inches throughout.
Average Liquid-Equivalent Monthly Snowfall
The length of the day in McChord Air Force Base varies significantly over the course of the year. In 2018, the shortest day is December 21, with 8 hours, 29 minutes of daylight; the longest day is June 21, with 15 hours, 55 minutes of daylight.
Hours of Daylight and Twilight
The earliest sunrise is at 5:13 AM on June 16, and the latest sunrise is 2 hours, 43 minutes later at 7:56 AM on January 1. The earliest sunset is at 4:20 PM on December 11, and the latest sunset is 4 hours, 50 minutes later at 9:09 PM on June 25.
Daylight saving time (DST) is observed in McChord Air Force Base during 2018, starting in the spring on March 11, lasting 7.8 months, and ending in the fall on November 4.
Sunrise & Sunset with Twilight and Daylight Saving Time
The perceived humidity level in McChord Air Force Base, 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
dry 55°F comfortable 60°F humid 65°F muggy 70°F oppressive 75°F miserable
The average hourly wind speed in McChord Air Force Base experiences mild seasonal variation over the course of the year.
The windier part of the year lasts for 6.2 months, from October 16 to April 22, with average wind speeds of more than 4.3 miles per hour. The windiest day of the year is November 30, with an average hourly wind speed of 5.3 miles per hour.
The calmer time of year lasts for 5.8 months, from April 22 to October 16. The calmest day of the year is August 2, with an average hourly wind speed of 3.2 miles per hour.
Average Wind Speed
The predominant average hourly wind direction in McChord Air Force Base varies throughout the year.
The wind is most often from the west for 3.9 months, from May 5 to September 2, with a peak percentage of 44% on June 20. The wind is most often from the north for 2.3 weeks, from September 2 to September 18, with a peak percentage of 32% on September 2. The wind is most often from the south for 7.6 months, from September 18 to May 5, with a peak percentage of 56% on January 1.
McChord Air Force Base 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 water temperature experiences some seasonal variation over the course of the year.
The time of year with warmer water lasts for 3.2 months, from June 24 to September 29, with an average temperature above 55°F. The day of the year with the warmest water is August 22, with an average temperature of 57°F.
The time of year with cooler water lasts for 4.0 months, from December 11 to April 12, with an average temperature below 49°F. The day of the year with the coolest water is February 10, with an average temperature of 47°F.
Average Water Temperature
Best Time of Year to Visit
To characterize how pleasant the weather is in McChord Air Force Base throughout the year, we compute two travel scores.
The tourism score favors clear, rainless days with perceived temperatures between 65°F and 80°F. Based on this score, the best time of year to visit McChord Air Force Base for general outdoor tourist activities is from mid July to late August, with a peak score in the first week of August.
The beach/pool score favors clear, rainless days with perceived temperatures between 75°F and 90°F. Based on this score, the best time of year to visit McChord Air Force Base for hot-weather activities is from mid July to mid August, with a peak score in the first week of August.
For each hour between 8:00 AM and 9:00 PM of each day in the analysis period (1980 to 2016), independent scores are computed for perceived temperature, cloud cover, and total precipitation. Those scores are combined into a single hourly composite score, which is then aggregated into days, averaged over all the years in the analysis period, and smoothed.
Our cloud cover score is 10 for fully clear skies, falling linearly to 9 for mostly clear skies, and to 1 for fully overcast skies.
Our precipitation score, which is based on the three-hour precipitation centered on the hour in question, is 10 for no precipitation, falling linearly to 9 for trace precipitation, and to 0 for 0.04 inches of precipitation or more.
Our tourism temperature score is 0 for perceived temperatures below 50°F, rising linearly to 9 for 65°F, to 10 for 75°F, falling linearly to 9 for 80°F, and to 1 for 90°F or hotter.
Our beach/pool temperature score is 0 for perceived temperatures below 65°F, rising linearly to 9 for 75°F, to 10 for 82°F, falling linearly to 9 for 90°F, and to 1 for 100°F or hotter.
The growing season in McChord Air Force Base typically lasts for 6.4 months (196 days), from around April 14 to around October 27, rarely starting before March 24 or after May 5, and rarely ending before October 5 or after November 19.
Time Spent in Various Temperature Bands and the Growing Season
Based on growing degree days alone, the first spring blooms in McChord Air Force Base should appear around April 16, only rarely appearing before March 29 or after May 6.
Growing Degree Days
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 3.2 months, from May 19 to August 24, with an average daily incident shortwave energy per square meter above 5.7 kWh. The brightest day of the year is July 21, with an average of 6.9 kWh.
The darker period of the year lasts for 3.8 months, from October 25 to February 19, with an average daily incident shortwave energy per square meter below 2.1 kWh. The darkest day of the year is December 24, with an average of 0.9 kWh.
Average Daily Incident Shortwave Solar Energy
For the purposes of this report, the geographical coordinates of McChord Air Force Base are 47.134 deg latitude, -122.492 deg longitude, and 295 ft elevation.
The topography within 2 miles of McChord Air Force Base contains only modest variations in elevation, with a maximum elevation change of 112 feet and an average elevation above sea level of 296 feet. Within 10 miles contains only modest variations in elevation (574 feet). Within 50 miles contains significant variations in elevation (14,383 feet).
The area within 2 miles of McChord Air Force Base is covered by artificial surfaces (70%) and trees (18%), within 10 miles by artificial surfaces (54%) and trees (27%), and within 50 miles by trees (52%) and shrubs (17%).
This report illustrates the typical weather in McChord Air Force Base, 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 2 weather stations near enough to contribute to our estimation of the temperature and dew point in McChord Air Force Base.
For each station, the records are corrected for the elevation difference between that station and McChord Air Force Base 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 McChord Air Force Base is computed as the weighted average of the individual contributions from each station, with weights proportional to the inverse of the distance between McChord Air Force Base and a given station.
Time zones for aiports and weather stations are provided by AskGeo.com .