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. Temperature | 40.1 | 43.5 | 45.6 | 49.2 | 55.1 | 60.9 | 65.2 | 65.5 | 60.6 | 52.8 | 45.3 | 40.5 | 52.0 |
| Avg. Max Temperature | 45.0 | 49.5 | 52.7 | 57.2 | 63.9 | 69.9 | 75.2 | 75.2 | 69.3 | 59.7 | 50.5 | 45.1 | 59.4 |
| Avg. Min Temperature | 35.2 | 37.4 | 38.5 | 41.2 | 46.3 | 51.9 | 55.2 | 55.7 | 51.9 | 45.8 | 40.1 | 35.8 | 44.6 |
| Days with Max Temp of 90 F or Higher | 0.0 | 0.0 | 0.0 | 0.0 | < 0.5 | < 0.5 | 1.0 | 1.0 | < 0.5 | 0.0 | 0.0 | 0.0 | 2.0 |
| Days with Min Temp Below Freezing | 10.0 | 6.0 | 3.0 | < 0.5 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | < 0.5 | 3.0 | 9.0 | 30.0 |
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| Seattle Sea-tac Airport Heating and Cooling |
Jan |
Feb |
Mar |
Apr |
May |
Jun |
Jul |
Aug |
Sep |
Oct |
Nov |
Dec |
Annual |
| Heating Degree Days | 772 | 602 | 601 | 474 | 307 | 144 | 58.0 | 65.0 | 156 | 378 | 591 | 760 | 4908 |
| Cooling Degree Days | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 21.0 | 64.0 | 81.0 | 24.0 | 0.0 | 0.0 | 0.0 | 190 |
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| Seattle Sea-tac Airport Precipitation |
Jan |
Feb |
Mar |
Apr |
May |
Jun |
Jul |
Aug |
Sep |
Oct |
Nov |
Dec |
Annual |
| Precipitation (inches) | 5.4 | 4.0 | 3.5 | 2.3 | 1.7 | 1.5 | 0.8 | 1.1 | 1.9 | 3.2 | 5.8 | 5.9 | 37.2 |
| Days with Precipitation 0.01 inch or More | 19.0 | 16.0 | 17.0 | 14.0 | 10.0 | 9.0 | 5.0 | 6.0 | 9.0 | 13.0 | 18.0 | 19.0 | 155 |
| Monthly Snowfall (inches) | 4.9 | 1.6 | 1.3 | 0.1 | < 0.05 | 0.0 | < 0.05 | 0.0 | < 0.05 | 0.0 | 1.1 | 2.4 | 11.4 |
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| Other Seattle Sea-tac Airport Weather Indicators |
Jan |
Feb |
Mar |
Apr |
May |
Jun |
Jul |
Aug |
Sep |
Oct |
Nov |
Dec |
Annual |
| Average Wind Speed | 9.6 | 9.5 | 9.5 | 9.4 | 8.9 | 8.7 | 8.2 | 7.8 | 8.1 | 8.5 | 9.3 | 9.6 | 8.9 |
| Clear Days | 3.0 | 3.0 | 3.0 | 3.0 | 4.0 | 5.0 | 10.0 | 9.0 | 8.0 | 4.0 | 2.0 | 2.0 | 58.0 |
| Partly Cloudy Days | 4.0 | 4.0 | 6.0 | 7.0 | 9.0 | 8.0 | 10.0 | 10.0 | 9.0 | 7.0 | 4.0 | 4.0 | 82.0 |
| Cloudy Days | 24.0 | 21.0 | 22.0 | 20.0 | 18.0 | 17.0 | 11.0 | 12.0 | 13.0 | 19.0 | 23.0 | 25.0 | 226 |
| Percent of Possible Sunshine | 28.0 | 40.0 | 50.0 | 52.0 | 56.0 | 56.0 | 65.0 | 65.0 | 62.0 | 43.0 | 28.0 | 23.0 | 47.0 |
| Avg. Relative Humidity | 60.0 | 77.0 | 75.0 | 72.5 | 70.5 | 69.0 | 67.0 | 66.0 | 68.0 | 72.0 | 75.5 | 78.5 | 80.5 |
Weather information for other cities in Washington