In late fall and early winter, atmospheric rivers (also known as " Pineapple Express " systems), strong frontal systems, and Pacific low-pressure systems are common. Rainfall To show variation within the month and not just the monthly total, we show the rainfall accumulated over a sliding 31-day period centered around each day. Monthly temperature, precipitation and hours of sunshine. Average monthly rainfall in Seattle (mm and inches) Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec mm 149 105 95 66 46 41 21 31 49 87 150 151 inches 5.9 4.1 3.7 2.6 1.8 1.6 0.8 1.2 1.9 3.4 5.9 5.9 Rainy days 18 15 16 13 The city is located in northwestern United States, in the state of Washington, of which it is the largest city. Average Annual Precipitation by City in the United States The tables below give annual averages for precipitation at the largest cities in the United States . Each city has a total for the amount of precipitation it usually receives in a year along with information on the number of days with wet weather. Seattle weather averages and climate Seattle, Washington. Seattle ranks 44th among major US cities for annual rainfall. Average weather, temperature, rainfall, sunshine hours In Seattle, the climate is sub-oceanic , with quite mild, rainy winters and mild, fairly sunny summers. A climate graph showing rainfall, temperatures and normals.

Av. November is the rainiest month in Seattle with 18.7 days of rain, and August is the driest month with only 5.3 rainy days. The average annual rainfall for the city of Seattle is 38 inches. The annual rainfall of 38.0 inches in Seattle means that it is about average compared to other places in Washington. Seattle experiences its heaviest rainfall during November, December, and January, receiving roughly half of its annual rainfall (by volume) during this period. The average sliding 31-day rainfall during June in Seattle is decreasing, starting the month at 2.0 inches, when it rarely exceeds 3.3 inches or falls below 0.5 inches, and ending the … Seattle averages 37.49 inches of precipitation a year, with the vast majority falling as rain instead of snow.