Average Weather at Grant County International Airport Washington, United States

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5. Grant County International Airport

At Grant County International Airport, the summers are hot and mostly clear, the winters are freezing and partly cloudy, and it is dry year round. Over the course of the year, the temperature typically varies from 23°F to 92°F and is rarely below 8°F or above 101°F.

The hot season lasts for 3.1 months, from June 12 to September 14, with an average daily high temperature above 80°F. The hottest day of the year is July 31, with an average high of 92°F and low of 59°F.

The cold season lasts for 3.0 months, from November 18 to February 19, 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 34°F.

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.

At Grant County International Airport, 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 at Grant County International Airport begins around June 6 and lasts for 4.1 months, ending around October 9. 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 9 and lasts for 7.9 months, ending around June 6. On January 15, the cloudiest day of the year, the sky is overcast or mostly cloudy 67% of the time, and clear, mostly clear, or partly cloudy 33% 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 at Grant County International Airport varies throughout the year.

The wetter season lasts 4.4 months, from October 23 to March 5, with a greater than 14% chance of a given day being a wet day. The chance of a wet day peaks at 24% on December 1.

The drier season lasts 7.6 months, from March 5 to October 23. The smallest chance of a wet day is 4% on August 20.

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 at Grant County International Airport changes throughout the year.

Rain alone is the most common for 11 months, from January 12 to December 24. The highest chance of a day with rain alone is 19% on November 10.

Snow alone is the most common for 2.7 weeks, from December 24 to January 12. The highest chance of a day with snow alone is 8% on January 1.

Rainfall

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. Grant County International Airport experiences some seasonal variation in monthly rainfall.

The rainy period of the year lasts for 8.0 months, from October 12 to June 11, 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 0.9 inches.

The rainless period of the year lasts for 4.0 months, from June 11 to October 12. The least rain falls around August 16, with an average total accumulation of 0.2 inches.

Snowfall

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. Grant County International Airport experiences some seasonal variation in monthly liquid-equivalent snowfall.

The snowy period of the year lasts for 3.2 months, from November 14 to February 20, 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 31, with an average total liquid-equivalent accumulation of 0.5 inches.

The snowless period of the year lasts for 8.8 months, from February 20 to November 14. The least snow falls around July 23, with an average total liquid-equivalent accumulation of 0.0 inches.

The length of the day at Grant County International Airport varies significantly over the course of the year. In 2017, the shortest day is December 21, with 8 hours, 29 minutes of daylight; the longest day is June 21, with 15 hours, 56 minutes of daylight.

The earliest sunrise is at 5:00 AM on June 16, and the latest sunrise is 2 hours, 45 minutes later at 7:45 AM on November 4. The earliest sunset is at 4:07 PM on December 11, and the latest sunset is 4 hours, 50 minutes later at 8:57 PM on June 25.

Daylight saving time (DST) is observed at Grant County International Airport during 2017, starting in the spring on March 12, lasting 7.8 months, and ending in the fall on November 5.

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 at Grant County International Airport, 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.

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 predominant average hourly wind direction at Grant County International Airport varies throughout the year.

The wind is most often from the south for 2.9 weeks, from February 24 to March 16 and for 1.8 months, from October 15 to December 8, with a peak percentage of 36% on November 10. The wind is most often from the west for 7.0 months, from March 16 to October 15, with a peak percentage of 53% on June 21. The wind is most often from the north for 2.6 months, from December 8 to February 24, with a peak percentage of 39% on January 1.

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 3.4 months, from May 10 to August 21, with an average daily incident shortwave energy per square meter above 6.4 kWh. The brightest day of the year is July 14, with an average of 7.7 kWh.

The darker period of the year lasts for 3.7 months, from October 27 to February 18, with an average daily incident shortwave energy per square meter below 2.5 kWh. The darkest day of the year is December 23, with an average of 1.2 kWh.

For the purposes of this report, the geographical coordinates of Grant County International Airport are 47.208 deg latitude, -119.320 deg longitude, and 1,161 ft elevation.

The topography within 2 miles of Grant County International Airport contains only modest variations in elevation, with a maximum elevation change of 141 feet and an average elevation above sea level of 1,171 feet. Within 10 miles also contains only modest variations in elevation (430 feet). Within 50 miles contains only modest variations in elevation (6,093 feet).

The area within 2 miles of Grant County International Airport is covered by shrubs (83%) and grassland (13%), within 10 miles by shrubs (48%) and cropland (37%), and within 50 miles by shrubs (53%) and cropland (36%).

This report illustrates the typical weather at Grant County International Airport, 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

Grant County International Airport has a weather station that reported reliably enough during the analysis period that we have included it in our network. When available, historical temperature and dew point measurements are taken directly from this weather station. These records are obtained from NOAA's Integrated Surface Hourly data set, falling back on ICAO METAR records as required.

In the case of missing or erroneous measurements from this station, we fall back on records from nearby stations, adjusted according to typical seasonal and diurnal intra-station differences. For a given day of the year and hour of the day, the fallback station is selected to minimize the prediction error over the years for which there are measurements for both stations.

The stations on which we may fall back include but are not limited to Ephrata Municipal Airport, Hanford, Pangborn Field, Tri-Cities Airport, Bowers Field, Omak Airport, Yakima Air Terminal Airport, and Walla Walla Regional Airport.

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.