Seattle Weather Averages

Seattle, Washington is a city of wet winters and dry summers. The moderate year-round temperatures mean that Seattle rarely sees snow, and yet the city enjoys pleasant summers.

This page gives detailed information on the annual temperature, precipitation, sun, humidity, wind and storm averages for Seattle. The weather measurements are averages based on climate data gathered at Seattle — Tacoma International Airport, located south of the city center.

Temperature

61 °F	annual average high	16 °C
46 °F	annual average low	8 °C

Seattle's coldest days of the year usually occur in mid December when the daily maximum temperature averages 46 degrees Fahrenheit (8 degrees Celsius) and the minimum averages 37 °F (3 °C).

The year's hottest days are normally at the end of July and beginning of August. The average temperature peaks then with daily highs of 79 °F (26 °C) and nighttime lows of 58 °F (14 °C).

94 days	70 °F max. or more (21 °C)
110 days	40 °F min. or less (4 °C)

Seattle averages 31 days a year when the thermometer reaches into the 80s °F (over 27 °C). The temperature typically climbs to 90 °F (32 °C) on four days a year. Days as hot as 100 °F (38 °C) are not normal for the city.

Nearly every day in Seattle is at least as warm as 40 °F (4 °C). Only once a year on average does the temperature remain below freezing for the entire day.

The thermometer dips to freezing or below on 25 nights each year. Seattle gets as chilly as 20 °F (-8 °C) on average just once a year.

Precipitation

39.3 in	total precipitation	999 mm
156 days	of rain or snowfall

November is usually the wettest month of the year in Seattle, while July is the driest.

Snow

6.3 in	total snowfall	16 cm
5 days	with new snow

Snow can fall in Seattle during any month from November to March. But more often than not for any individual month, except February, the city sees no snow. Seattle averages just one day a year when the snow covering the ground accumulates to 3 inches (8 cm) or more.

Sun

43 %	sunshine
71 days	clear skies

The sun's rays reach the ground in Seattle during 43 percent of daylight hours on average year round, for a total of 1922 hours annually. Typically on 71 days a year the sky is mainly clear, with at most 30 percent cloud cover.

Sunlight in Seattle averages 12 hours and 14 minutes a day. The shortest days of the year in mid December have 8 hours and 25 minutes of daylight. The year's longest days in mid June last 15:59 from sunrise to sunset.

Humidity

73 %	average humidity

The annual average for relative humidity in Seattle ranges throughout the day from 83 percent at 4:00 am to 62 percent at 4:00 pm standard time.

Local Time	1 am	4 am	7 am	10 am	1 pm	4 pm	7 pm	10 pm
Humidity %	80	83	82	73	64	62	68	75

Wind

8.8 mph

wind speed average

14.2 kph

January and December are usually the windiest months for Seattle, while the wind is calmest during August.

Storms

6 days	precipitation of 1 inch (25 mm) or more
2 days	snowfall of 3 inches (8 cm) or more
7 days	with thunderstorms a year

Heavy rainstorms are mainly a winter event, most commonly arriving during November to January.

Seattle is most likely to get a heavy snowstorm during December. About once a decade the city gets a snow dump of 10 inches (25 cm) or more in a single day.

Thunderstorms most commonly appear over Seattle during April and July, although they can arrive during any month.