Climate Overview
The climate in Seattle-Tacoma International Airport is temperate. The average annual temperature is 11°C and approximately 1369mm of precipitation falls per year. January is the wettest month, receiving around 200mm of rainfall. Seattle-Tacoma International Airport is in the Northern Hemisphere. Summer begins at the end of June and lasts through September. The summer months are: August, July, September. The coldest months are February, December, January, when temperatures can drop to 3°C. Snowfall occurs from January to December, with around 61cm accumulating over the season.
Temperature
Temperatures in Seattle-Tacoma International Airport vary considerably across the year, with a 22°C difference between the coldest and warmest months. August is the warmest month, though highs remain moderate at 25°C with a mean of 19°C. February is the coolest month, with minimum temperatures around 3°C and an average of 5°C. Daily temperature variation is modest, with an average difference of 7°C between highs and lows. The sharpest temperature change occurs between September and October, with a 5°C shift in average temperatures.
Precipitation
Seattle-Tacoma International Airport is a fairly wet location, receiving approximately 1369mm of precipitation annually, which averages out to around 114mm per month. The wettest month is January, averaging 200mm of rainfall. December and November also tend to see above-average precipitation. The driest month is August, with just 14mm. That's 186mm less than January, the wettest month. Rainfall is heavily concentrated in certain months, creating a distinct wet and dry season. Visitors should plan around these patterns, as the difference between peak and low months is dramatic. Snowfall is a regular feature from January to December, with around 61cm accumulating over the season. February typically sees the most snow at around 26cm.
Wind
Seattle-Tacoma International Airport is relatively calm, with an average annual wind speed of 3km/h. For context, sustained winds below 12km/h are generally light, while anything above 25km/h is considered strong. The windiest month is November, averaging 3km/h, though still comfortable for most outdoor activities. The calmest conditions occur in August, with average winds dropping to 2km/h, making it an ideal period for wind-sensitive activities. Wind conditions are fairly consistent throughout the year, varying by only 1km/h between the calmest and windiest months.
Seasons
4 days until Summer
It is currently spring in Seattle-Tacoma International Airport, which began on March 20, 2026. Seattle-Tacoma International Airport is in the Northern Hemisphere, where spring begins in March, summer in June, autumn in September, and winter in December. The warmest period peaks in August at around 25°C, while the coldest stretch bottoms out in February near 3°C. Summer is next, beginning on June 21, 2026 — 4 days from now.
Spring
Temperatures range from 5 to 19°C. Rainfall is heavy, totalling around 317mm across the season with a monthly average of 106mm. Winds are generally light, averaging 3km/h. An umbrella or waterproof jacket is advisable as spring showers are frequent.
Summer
Temperatures range from 12 to 25°C. Rainfall is relatively light, with around 85mm over the season and a monthly average of 28mm. Winds are generally light, averaging 2km/h. Comfortable clothing with a light layer for cooler evenings is all you need.
Autumn
Temperatures range from 6 to 21°C. Rainfall is heavy, totalling around 417mm across the season with a monthly average of 139mm. Winds are generally light, averaging 3km/h. A waterproof jacket and sturdy footwear are recommended as rain becomes more frequent.
Winter
Temperatures range from 3 to 8°C. Rainfall is heavy, totalling around 550mm across the season with a monthly average of 183mm. Expect around 48cm of snow accumulation during this period. Winds are generally light, averaging 3km/h. A light jacket or sweater is usually sufficient, though cooler evenings may call for an extra layer.
Best Time to Visit
The best time to visit Seattle-Tacoma International Airport is during June, July, August and September, when the weather is most comfortable for travellers. During these months, average temperatures hover around 17°C with modest rainfall averaging 42mm per month. By contrast, February can be quite cold with temperatures dropping to 3°C. A light rain jacket is recommended, though showers are generally brief and shouldn't disrupt your plans.
Monthly Climate Data
The table below shows monthly climate averages for Seattle-Tacoma International Airport based on historical weather data. Min and max temperatures represent typical overnight lows and afternoon highs for each month, shown in degrees Celsius (°C). Precipitation is measured in millimetres (mm) and indicates the average total rainfall per month. Snow is measured in centimetres (cm) and reflects average monthly snowfall accumulation. Wind speed is the average sustained speed in kilometres per hour (km/h). All values are based on averages from over 10 years of historical weather data. The current month is highlighted for quick reference.
