Seattle, WA climate
Seattle has mild winters and pleasant summers. A typical July afternoon reaches 77°, a January night drops to 37°, and about 4 inches of snow falls in a normal winter.
NOAA 1991-2020 climate normals Updated once a decadeWhat a year in Seattle feels like
Winter
Spring
Summer
Fall
Seattle weather by month
Average highs, lows, rain and snow for every month, from NOAA’s 1991–2020 normals.
| Month | High | Low | Rain + melt | Snow | Wet days | Snow on ground | 30-yr range |
|---|---|---|---|---|---|---|---|
| January | 48° | 37° | 5.2" | 0.9" | 19 | 1 | 38° – 46° |
| February | 50° | 37° | 3.7" | 1.0" | 16 | 1 | 37° – 49° |
| March | 55° | 39° | 4.2" | 0 | 18 | 0 | 42° – 51° |
| April | 60° | 42° | 3.0" | 0 | 16 | 0 | 47° – 56° |
| May | 66° | 48° | 2.0" | 0 | 12 | 0 | 53° – 61° |
| June | 71° | 52° | 1.5" | 0 | 11 | 0 | 58° – 67° |
| July | 77° | 56° | 0.7" | 0 | 5 | 0 | 62° – 71° |
| August | 77° | 56° | 1.0" | 0 | 6 | 0 | 62° – 69° |
| September | 71° | 52° | 1.6" | 0 | 9 | 0 | 59° – 65° |
| October | 61° | 46° | 3.7" | 0 | 15 | 0 | 50° – 58° |
| November | 52° | 40° | 5.8" | 0.2" | 19 | 0 | 42° – 51° |
| December | 46° | 36° | 5.6" | 1.7" | 20 | 1 | 37° – 45° |
| Year | 61° | 45° | 38.0" | 3.8" | 163 | 2 |
“Wet days” have at least 0.01" of rain or melted snow. “Snow on ground” counts days with 1" or more. The 30-year range is the coldest and warmest that month’s average temperature got between 1991 and 2020.
Rain and snow in Seattle
Seattle gets 38 inches of rain and melted snow a year. November is the wettest month and July the driest. Rain or snow falls on about 163 days a year.
About 259 frost-free days a year
In half of years the last 32° night comes by March 8 and the first one by November 23. That leaves about 259 frost-free days for gardens, longer than 92% of U.S. towns.
Heating and cooling a home in Seattle
Engineers use “degree days” to estimate how hard a furnace or air conditioner works. In Seattle, 96% of that work is heating and 4% is cooling, so the furnace matters far more than the air conditioner.
Degree days measure how far each day’s average temperature falls below or rises above 65°, added up over a year. Source: NOAA station normals.
Seattle and its neighbors
Seattle borders 12 towns with climate data. January nights across them vary by 0.8°. Shoreline has the coldest January nights (36°) and Mercer Island the hottest July afternoons (77°). Seattle’s January low is 37° and its July high 77°.
Temperatures and rain come from NOAA’s 5 km grid, so each town gets its own value.
How Seattle compares
Compared with every U.S. town and city on TownTapestry, each counted once.
Warmer than it used to be
The last 30 years in Seattle averaged 1.3° warmer than the 1900s. The biggest change is in January (+2.6°). The shift is larger than in 53% of U.S. towns.
Change by month1991–2020 average minus 1901–2000 average, at Seattle’s spot on NOAA’s grid
How much a month can swing
A normal is an average, and real years wander around it. February swings the most: between 1991 and 2020 its average temperature ranged from 37° to 49°. September is the most reliable, staying within 6°.
Common questions about Seattle’s climate
What is the coldest month in Seattle?
December, with a typical high of 46° and a low of 36°.
What is the hottest month in Seattle?
August, with a typical high of 77° and a low of 56°. About 2 days a year reach 90°.
How much snow does Seattle get?
About 4 inches in a normal winter, most of it in December.
When is the first frost in Seattle?
In half of years the first 32° night comes by November 23, and the last spring frost by March 8.
What is the rainiest month in Seattle?
November, with 5.8 inches of rain and melted snow. The year totals 38 inches.
Temperatures and rainfall come from NOAA’s gridded climate normals for Seattle itself (about a 3-mile square). Snow, frost dates and day counts come from NOAA’s weather station at Seattle Sand Pt WSFO, WA (6 mi) away. Normals are 30-year averages, not a forecast. Source: NOAA NCEI U.S. Climate Normals, 1991–2020 and 1901–2000.