Average Weather in Millwood Washington, United States
In Millwood, the summers are short, warm, dry, and mostly clear and the winters are very cold and mostly cloudy. Over the course of the year, the temperature typically varies from 26°F to 88°F and is rarely below 11°F or above 97°F.
The hot season lasts for 2.8 months, from June 20 to September 12, with an average daily high temperature above 78°F. The hottest day of the year is August 3, with an average high of 88°F and low of 58°F.
The cold season lasts for 3.4 months, from November 13 to February 24, with an average daily high temperature below 46°F. The coldest day of the year is December 30, with an average low of 26°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 Millwood, 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 Millwood begins around June 7 and lasts for 4.1 months, ending around October 10. On July 29, the clearest day of the year, the sky is clear, mostly clear, or partly cloudy 79% of the time, and overcast or mostly cloudy 21% of the time.
The cloudier part of the year begins around October 10 and lasts for 7.9 months, ending around June 7. On January 10, the cloudiest day of the year, the sky is overcast or mostly cloudy 74% of the time, and clear, mostly clear, or partly cloudy 26% of the time.
Cloud Cover Categories
A wet day is one with at least 0.04 inches of liquid or liquid-equivalent precipitation. The chance of wet days in Millwood varies significantly throughout the year.
The wetter season lasts 7.6 months, from October 20 to June 8, with a greater than 23% chance of a given day being a wet day. The chance of a wet day peaks at 39% on November 28.
The drier season lasts 4.4 months, from June 8 to October 20. The smallest chance of a wet day is 7% 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 throughout the year is rain alone, with a peak probability of 34% on November 10.
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. Millwood experiences significant seasonal variation in monthly rainfall.
The rainy period of the year lasts for 11 months, from August 19 to July 28, with a sliding 31-day rainfall of at least 0.5 inches. The most rain falls during the 31 days centered around November 21, with an average total accumulation of 2.6 inches.
The rainless period of the year lasts for 3.2 weeks, from July 28 to August 19. The least rain falls around August 9, with an average total accumulation of 0.5 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. Millwood experiences some seasonal variation in monthly liquid-equivalent snowfall.
The snowy period of the year lasts for 4.0 months, from November 13 to March 11, with a sliding 31-day liquid-equivalent snowfall of at least 0.1 inches. The most snow falls during the 31 days centered around January 1, with an average total liquid-equivalent accumulation of 0.6 inches.
The snowless period of the year lasts for 8.0 months, from March 11 to November 13. The least snow falls around July 17, with an average total liquid-equivalent accumulation of 0.0 inches.
Average Liquid-Equivalent Monthly Snowfall
The length of the day in Millwood varies significantly over the course of the year. In 2017, the shortest day is December 21, with 8 hours, 25 minutes of daylight; the longest day is June 20, with 15 hours, 60 minutes of daylight.
Hours of Daylight and Twilight
The earliest sunrise is at 4:50 AM on June 15, and the latest sunrise is 2 hours, 48 minutes later at 7:38 AM on November 4. The earliest sunset is at 3:57 PM on December 11, and the latest sunset is 4 hours, 54 minutes later at 8:51 PM on June 25.
Daylight saving time (DST) is observed in Millwood 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
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 Millwood, 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
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 Millwood experiences mild seasonal variation over the course of the year.
The windier part of the year lasts for 3.3 months, from February 3 to May 14, with average wind speeds of more than 5.9 miles per hour. The windiest day of the year is March 26, with an average hourly wind speed of 6.5 miles per hour.
The calmer time of year lasts for 8.6 months, from May 14 to February 3. The calmest day of the year is August 12, with an average hourly wind speed of 5.4 miles per hour.
Average Wind Speed
The predominant average hourly wind direction in Millwood varies throughout the year.
The wind is most often from the west for 3.9 weeks, from April 23 to May 20 and for 3.0 months, from June 27 to September 28, with a peak percentage of 41% on August 29. The wind is most often from the south for 1.2 months, from May 20 to June 27 and for 6.8 months, from September 28 to April 23, with a peak percentage of 39% on June 11.
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 17 to August 21, with an average daily incident shortwave energy per square meter above 6.2 kWh. The brightest day of the year is July 15, with an average of 7.5 kWh.
The darker period of the year lasts for 3.8 months, from October 26 to February 19, with an average daily incident shortwave energy per square meter below 2.3 kWh. The darkest day of the year is December 26, with an average of 1.0 kWh.
Average Daily Incident Shortwave Solar Energy
For the purposes of this report, the geographical coordinates of Millwood are 47.681 deg latitude, -117.283 deg longitude, and 2,001 ft elevation.
The topography within 2 miles of Millwood contains only modest variations in elevation, with a maximum elevation change of 456 feet and an average elevation above sea level of 1,991 feet. Within 10 miles contains only modest variations in elevation (2,129 feet). Within 50 miles contains large variations in elevation (5,052 feet).
The area within 2 miles of Millwood is covered by artificial surfaces (69%) and shrubs (28%), within 10 miles by shrubs (44%) and artificial surfaces (23%), and within 50 miles by shrubs (30%) and trees (29%).
This report illustrates the typical weather in Millwood, 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 Millwood.
For each station, the records are corrected for the elevation difference between that station and Millwood 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 Millwood is computed as the weighted average of the individual contributions from each station, with weights proportional to the inverse of the distance between Millwood and a given station.
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.
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.