Our weather and climate analysis offers a detailed understanding of average weather patterns for locations across the globe. Derived from 26 years of historical simulated weather data from ECMWF, it provides valuable insights into typical weather conditions, including air temperature, humidity, precipitation, cloud cover and wind. It is important to note the data is not observational, but rather derived from climate reanalysis.
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United States > Seattle, WA > Overview
Discover if upcoming months are expected to be warmer, colder, wetter, or drier than average
What is the best time to visit Seattle to enjoy the optimal weather conditions?
This quick reference weather table contains a summary of the annual climate trends in Seattle. It contains key metrics, including average monthly high & low temperatures, rainfall, humidity and UV index. The data is presented on a monthly basis, allowing you to see how each these weather components change throughout the year.
Seattle's long-term climate patterns earn these Weather Badges.
Explore the most extreme weather events in Seattle over the past 26 years, including record highs and lows for temperatures, rainfall, and wind speeds. This data is sourced from the latest ERA5 reanalysis model spanning 2000 to 2025.
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Weather guides, climate insights, and travel planning stories that talk about Seattle.
Seattle experiences a temperate marine climate characterized by cool, wet winters and warm, dry summers. WeatherBox data shows that the city accumulates a substantial annual precipitation total of 1,340 mm (53 in), though this moisture is unevenly distributed across the calendar. The atmosphere shifts dramatically between seasons; heavy cloud cover dominates the winter months with 90.4 coverage, while the summer season clears significantly to 36.4 cloud density.
Thermal conditions are moderate, shielding the region from intense heat or bitter cold. Summer afternoons are typically pleasant rather than scorching, with average daily highs reaching 23.9°C (75.0°F). Extreme heat is statistically rare, as temperatures seldom exceed 28.5°C (83.3°F). During the cooler months, mild winters prevail. Average lows sit at 3.4°C (38.1°F), and the temperature rarely falls below -0.8°C (30.6°F), keeping prolonged freezing events uncommon.
Rainfall intensity peaks late in the year, creating persistent dampness. The wettest month records 194 mm (8 in) of precipitation, often accompanied by high relative humidity averaging 85.0. In sharp contrast, the mid-summer months offer sunny, dry conditions with rainfall dropping to a low of 22 mm (1 in). During this brighter period, sunshine hours peak at 318.8 and the average peak UV Index is 6.5. Prevailing winds from the SSW remain generally moderate, rarely exceeding 26.3 km/h (16.4 mph).
Explore advanced weather charts and detailed climate statistics for this location on the WeatherBox website.