Sammamish, WA climate
Sammamish has mild winters and cool summers, with plenty of rain. A typical July afternoon reaches 76°, a January night drops to 36°, and about 4 inches of snow falls in a normal winter.
NOAA 1991-2020 climate normals Updated once a decadeWhat a year in Sammamish feels like
Winter
Spring
Summer
Fall
Sammamish 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 | 47° | 36° | 6.6" | 1.5" | 21 | 1 | 37° – 45° |
| February | 49° | 36° | 4.5" | 0.2" | 16 | 0 | 35° – 48° |
| March | 53° | 37° | 5.2" | 0.3" | 20 | 0 | 41° – 50° |
| April | 58° | 41° | 3.9" | 0 | 18 | 0 | 45° – 55° |
| May | 65° | 47° | 2.8" | 0 | 15 | 0 | 51° – 60° |
| June | 69° | 51° | 2.2" | 0 | 13 | 0 | 57° – 66° |
| July | 76° | 55° | 1.0" | 0 | 7 | 0 | 61° – 69° |
| August | 76° | 55° | 1.2" | 0 | 6 | 0 | 61° – 69° |
| September | 70° | 51° | 2.2" | 0 | 11 | 0 | 58° – 64° |
| October | 60° | 44° | 4.9" | 0 | 17 | 0 | 49° – 57° |
| November | 51° | 39° | 7.2" | 0.1" | 21 | 0 | 41° – 49° |
| December | 45° | 35° | 6.8" | 1.5" | 20 | 1 | 36° – 44° |
| Year | 60° | 44° | 48.3" | 3.6" | 184 | 3 |
“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 Sammamish
Sammamish gets 48 inches of rain and melted snow a year. November is the wettest month and July the driest. Rain or snow falls on about 184 days a year.
About 223 frost-free days a year
In half of years the last 32° night comes by March 30 and the first one by November 7. That leaves about 223 frost-free days for gardens, longer than 83% of U.S. towns.
Heating and cooling a home in Sammamish
Engineers use “degree days” to estimate how hard a furnace or air conditioner works. In Sammamish, 97% of that work is heating and 3% 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.
Sammamish and its neighbors
Sammamish borders 3 towns with climate data. January nights across them vary by 0.4°. Issaquah has both the coldest January nights (36°) and the hottest July afternoons (77°). Sammamish’s January low is 36° and its July high 76°.
Temperatures and rain come from NOAA’s 5 km grid, so each town gets its own value.
How Sammamish 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 Sammamish averaged 0.9° warmer than the 1900s. The biggest change is in January (+2.6°). The shift is smaller than in 78% of U.S. towns.
Change by month1991–2020 average minus 1901–2000 average, at Sammamish’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 35° to 48°. September is the most reliable, staying within 6°.
Common questions about Sammamish’s climate
What is the coldest month in Sammamish?
December, with a typical high of 45° and a low of 35°.
What is the hottest month in Sammamish?
August, with a typical high of 76° and a low of 55°. About 3 days a year reach 90°.
How much snow does Sammamish get?
About 4 inches in a normal winter, most of it in January.
When is the first frost in Sammamish?
In half of years the first 32° night comes by November 7, and the last spring frost by March 30.
What is the rainiest month in Sammamish?
November, with 7.2 inches of rain and melted snow. The year totals 48 inches.
Temperatures and rainfall come from NOAA’s gridded climate normals for Sammamish itself (about a 3-mile square). Snow, frost dates and day counts come from NOAA’s weather station at Snoqualmie Falls, WA (10 mi) away. Normals are 30-year averages, not a forecast. Source: NOAA NCEI U.S. Climate Normals, 1991–2020 and 1901–2000.