Seattle Sea-tac Airport

The tables below display average monthly climate and weather indicators in Seattle Sea-tac Airport Washington.

Temperature by: Fahrenheit / Centigrade

Seattle Sea-tac Airport Temperature Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Annual
Avg. Temperature40.143.545.649.255.160.965.265.560.652.845.340.552.0
Avg. Max Temperature45.049.552.757.263.969.975.275.269.359.750.545.159.4
Avg. Min Temperature35.237.438.541.246.351.955.255.751.945.840.135.844.6
Days with Max Temp of 90 F or Higher0.00.00.00.0< 0.5< 0.51.01.0< 0.50.00.00.02.0
Days with Min Temp Below Freezing10.06.03.0< 0.50.00.00.00.00.0< 0.53.09.030.0
 
Seattle Sea-tac Airport Heating and Cooling Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Annual
Heating Degree Days77260260147430714458.065.01563785917604908
Cooling Degree Days0.00.00.00.00.021.064.081.024.00.00.00.0190
 
Seattle Sea-tac Airport Precipitation Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Annual
Precipitation (inches)5.44.03.52.31.71.50.81.11.93.25.85.937.2
Days with Precipitation 0.01 inch or More19.016.017.014.010.09.05.06.09.013.018.019.0155
Monthly Snowfall (inches)4.91.61.30.1< 0.050.0< 0.050.0< 0.050.01.12.411.4
 
Other Seattle Sea-tac Airport Weather Indicators Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Annual
Average Wind Speed9.69.59.59.48.98.78.27.88.18.59.39.68.9
Clear Days3.03.03.03.04.05.010.09.08.04.02.02.058.0
Partly Cloudy Days4.04.06.07.09.08.010.010.09.07.04.04.082.0
Cloudy Days24.021.022.020.018.017.011.012.013.019.023.025.0226
Percent of Possible Sunshine28.040.050.052.056.056.065.065.062.043.028.023.047.0
Avg. Relative Humidity60.077.075.072.570.569.067.066.068.072.075.578.580.5

Weather information for other cities in Washington

Portions of this site are based on the CIA World Fact Book, a public-domain work
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