Average Weather in May in Federal Way Washington, United States
Daily high temperatures increase by 5°F, from 62°F to 68°F, rarely falling below 54°F or exceeding 79°F.
Daily low temperatures increase by 5°F, from 45°F to 50°F, rarely falling below 39°F or exceeding 55°F.
For reference, on August 3, the hottest day of the year, temperatures in Federal Way typically range from 57°F to 78°F, while on January 1, the coldest day of the year, they range from 37°F to 45°F.
Average High and Low Temperature in May
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
The month of May in Federal Way experiences essentially constant cloud cover, with the percentage of time that the sky is overcast or mostly cloudy remaining about 57% throughout the month.
The clearest day of the month is May 31, with clear, mostly clear, or partly cloudy conditions 45% of the time.
For reference, on January 19, the cloudiest day of the year, the chance of overcast or mostly cloudy conditions is 74%, while on August 3, the clearest day of the year, the chance of clear, mostly clear, or partly cloudy skies is 76%.
Cloud Cover Categories in May
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. In Federal Way, the chance of a wet day over the course of May is decreasing, starting the month at 33% and ending it at 29%.
For reference, the year's highest daily chance of a wet day is 58% on November 18, and its lowest chance is 8% on August 5.
Probability of Precipitation in May
The average sliding 31-day rainfall during May in Federal Way is decreasing, starting the month at 2.6 inches, when it rarely exceeds 4.5 inches or falls below 1.0 inches, and ending the month at 2.1 inches, when it rarely exceeds 3.6 inches or falls below 0.6 inches.
Average Monthly Rainfall in May
Over the course of May in Federal Way, 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, 12 minutes, implying an average daily increase of 2 minutes, 23 seconds, and weekly increase of 16 minutes, 43 seconds.
The shortest day of the month is May 1, with 14 hours, 28 minutes of daylight and the longest day is May 31, with 15 hours, 40 minutes of daylight.
Hours of Daylight and Twilight in May
The latest sunrise of the month in Federal Way is 5:52 AM on May 1 and the earliest sunrise is 35 minutes earlier at 5:17 AM on May 31.
The earliest sunset is 8:20 PM on May 1 and the latest sunset is 36 minutes later at 8:57 PM on May 31.
Daylight saving time is observed in Federal Way during 2018, 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 5:12 AM and sets 15 hours, 57 minutes later, at 9:09 PM, while on December 21, the shortest day of the year, it rises at 7:53 AM and sets 8 hours, 28 minutes later, at 4:21 PM.
Sunrise & Sunset with Twilight in May
The chance that a given day will be muggy in Federal Way is essentially constant during May, remaining around 0% throughout.
For reference, on September 13, 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
dry 55°F comfortable 60°F humid 65°F muggy 70°F oppressive 75°F miserable
The average hourly wind speed in Federal Way is essentially constant during May, remaining within 0.2 miles per hour of 3.7 miles per hour throughout.
For reference, on November 30, the windiest day of the year, the daily average wind speed is 5.3 miles per hour, while on August 2, the calmest day of the year, the daily average wind speed is 3.0 miles per hour.
Average Wind Speed in May
Wind Direction in May
Federal Way 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 surface water temperature in Federal Way is gradually increasing during May, rising by 3°F, from 50°F to 53°F, over the course of the month.
Average Water Temperature in May
The growing season in Federal Way typically lasts for 8.2 months (253 days), from around March 9 to around November 17, rarely starting before February 10 or after April 4, and rarely ending before October 28 or after December 16.
The month of May in Federal Way is reliably fully within the growing season.
Time Spent in Various Temperature Bands and the Growing Season in May
The average accumulated growing degree days in Federal Way are increasing during May, increasing by 182°F, from 131°F to 313°F, over the course of the month.
Growing Degree Days in May
The average daily incident shortwave solar energy in Federal Way is gradually increasing during May, rising by 0.7 kWh, from 5.2 kWh to 5.8 kWh, over the course of the month.
Average Daily Incident Shortwave Solar Energy in May
For the purposes of this report, the geographical coordinates of Federal Way are 47.322 deg latitude, -122.313 deg longitude, and 351 ft elevation.
The topography within 2 miles of Federal Way contains significant variations in elevation, with a maximum elevation change of 525 feet and an average elevation above sea level of 386 feet. Within 10 miles also contains significant variations in elevation (705 feet). Within 50 miles contains significant variations in elevation (14,383 feet).
The area within 2 miles of Federal Way is covered by artificial surfaces (95%), within 10 miles by artificial surfaces (63%) and water (20%), and within 50 miles by trees (53%) and shrubs (15%).
This report illustrates the typical weather in Federal Way 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 Federal Way.
For each station, the records are corrected for the elevation difference between that station and Federal Way 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 Federal Way is computed as the weighted average of the individual contributions from each station, with weights proportional to the inverse of the distance between Federal Way and a given station.
The stations contributing to this reconstruction are: Seattle-Tacoma International Airport (42%, 14 kilometers, north); Tacoma Narrows Airport (22%, 21 kilometers, west); McChord Field Airport (Joint Base Lewis-McChord) (19%, 23 kilometers, southwest); and Pierce County Airport Thun Field (17%, 24 kilometers, south).
Time zones for aiports and weather stations are provided by AskGeo.com .