SeaTac (WA) Weather & Climate: Best Time to Visit
Average temperatures, rainfall, sunshine and the best time to visit SeaTac.
Climate overview of SeaTac
SeaTac, Washington State, United States of America, sees big temperature differences between seasons, with July peaking at 25°C (77°F) and December dropping to 8°C (46°F).
The city receives considerable rain/snowfall, with around 1006 mm (40 in) annually. November is the wettest month. It has a distinct dry season from June to August. Sunshine peaks in July, when the city sees around 10.4 hours of sunshine per day.
SeaTac Weather by Month
Pick a month to see the average temperature, rainfall and sunshine in SeaTac — and find the best time to visit.
Monthly Temperature in SeaTac
Visitors to SeaTac can expect significant temperature changes throughout the year. Typically, average maximum daytime temperatures range from a comfortable 25°C (77°F) in July to a chilly 8°C (46°F) in the coolest month, December.
Nights vary from 14°C (57°F) in July to around 2°C (36°F) during the colder months.
Check out our detailed temperature page for more information.
Temperature ranges by month
Rainfall in SeaTac
SeaTac is known for its substantial rain/snowfall, with annual precipitation reaching 1006 mm (40 in). The climate in SeaTac shows significant variation throughout the year. Expect heavy rainfall in November, the wettest month, with an average of 165 mm (6.5 in) of precipitation over 20 rainy days.
In contrast, the driest month July offers drier and sunnier days, with around 14 mm (0.6 in) of rainfall over 4 rainy days. For more details, please visit our SeaTac Precipitation page.
The mean monthly precipitation over the year, including rain, hail, and snow
The average number of days each month with precipitation
Sunshine Hours in SeaTac
For those who appreciate different seasons, SeaTac serves as an ideal destination. Expect longer, more sun-filled days in July with an average of 10.4 hours of sunshine daily, and embrace the darker days in December, offering only 1.8 hours of daily sunlight.
Visit our detailed sunshine hours page for more information.
Monthly hours of sunshine
Daily hours of sunshine
Daily percentage of sunshine
Humidity in SeaTac by Month
The relative humidity is high throughout the year in SeaTac.
The city experiences its highest humidity in December, reaching 80%. In July, the humidity drops to its lowest level at 65%. What does this mean? Read our detailed page on humidity levels for further details.
Relative humidity over the year
Wind Speed in SeaTac
The mean wind speed over the year ranges from 4 m/s (8 knots) in February, April, May, June, July, August, September, October, November and December to 5 m/s (10 knots) in January and March. What does this mean?
The mean monthly wind speed over the year (meters per second)
Best Time to Visit SeaTac
The weather does bring rainfall during this period, between 14 mm (0.6 in) and 54 mm (2.1 in).
Plan accordingly for November, when conditions bring the heaviest precipitation. Ready to plan your travels but need destination ideas? Our smart tool recommends places based on the climate conditions you prefer. Start planning with our destination weather tool.
Frequently asked questions about the climate in SeaTac
What is the best time to visit SeaTac?
June, July, August and September typically offer the most optimal weather in SeaTac. In contrast, January, February, March, November and December tend to have less optimal conditions. SeaTac has a distinct dry season from June to August.
What temperatures can I expect in SeaTac?
Daytime highs range from 8°C (46°F) in December to 25°C (77°F) in July. Nighttime lows range from 2°C (36°F) to 14°C (57°F). Temperatures vary considerably through the year.
How much rain does SeaTac get?
Annual rainfall is around 1006 mm (40 in). November is the wettest month with 165 mm (6.5 in), while July is the driest with 14 mm (0.6 in).
How sunny is SeaTac?
SeaTac receives around 2,171 hours of sunshine per year. July is the sunniest month with 312 hours, while December is the cloudiest with just 54 hours. Overall, SeaTac enjoys abundant sunshine.
SeaTac 3-Day Forecast
SeaTac (WA) 3-Day Forecast
SeaTac on the map
SeaTac is highlighted — select any city to see its climate.
Popular this month
Where to go in July — average daytime high across popular destinations.
Bucket list
Need travel inspiration? Check out our bucket list articles and be inspired.
Yosemite National Park is definitely worth a visit
Vast forests, blue lakes, towering sequoias, and majestic waterfalls hint at the beauty of Yosemite National Park—a true natural masterpiece.
The 10 most alternative cities in the United States
Discover the top 10 fun and alternative U.S. cities rich in art, culture, and adventure. From Portland's hippy charm to Sedona's stunning landscapes.
Sedona: Explore Majestic Red Rock Landscapes
A picturesque artists' town surrounded by red rocks and known for its spirituality, vortex energy, and stunning hikes like Cathedral Rock.
10 most idyllic villages to visit in the United States
Discover 10 idyllic villages in the USA, from California to Vermont. Explore their unique charm, rich history, stunning nature, and vibrant arts scenes.