Roslyn, WA climate
Roslyn has chilly winters and cool summers, with plenty of rain. A typical July afternoon reaches 73°, a January night drops to 24°.
NOAA 1991-2020 climate normals Updated once a decadeWhat a year in Roslyn feels like
Winter
Spring
Summer
Fall
Roslyn weather by month
Average highs, lows, rain and snow for every month, from NOAA’s 1991–2020 normals.
| Month | High | Low | Rain + melt | 30-yr range |
|---|---|---|---|---|
| January | 33° | 24° | 9.4" | 22° – 35° |
| February | 37° | 25° | 6.1" | 23° – 38° |
| March | 43° | 28° | 5.5" | 30° – 42° |
| April | 49° | 32° | 3.3" | 35° – 47° |
| May | 58° | 38° | 2.4" | 43° – 53° |
| June | 63° | 43° | 1.6" | 49° – 62° |
| July | 73° | 49° | 0.7" | 53° – 65° |
| August | 73° | 50° | 0.8" | 56° – 66° |
| September | 65° | 45° | 1.7" | 51° – 60° |
| October | 52° | 37° | 5.6" | 40° – 49° |
| November | 39° | 29° | 8.8" | 29° – 39° |
| December | 32° | 24° | 9.4" | 24° – 32° |
| Year | 51° | 35° | 55.3" |
“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 Roslyn
Roslyn gets 55 inches of rain and melted snow a year. December is the wettest month and July the driest.
About 151 frost-free days a year
In half of years the last 32° night comes by May 9 and the first one by October 6. That leaves about 151 frost-free days for gardens, shorter than 80% of U.S. towns.
Heating and cooling a home in Roslyn
Engineers use “degree days” to estimate how hard a furnace or air conditioner works. In Roslyn, 99% of that work is heating and 1% 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.
How Roslyn 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 Roslyn averaged 1.2° warmer than the 1900s. The biggest change is in January (+3.9°). The shift is larger than in 50% of U.S. towns.
Change by month1991–2020 average minus 1901–2000 average, at Roslyn’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 23° to 38°. December is the most reliable, staying within 8°.
Common questions about Roslyn’s climate
What is the coldest month in Roslyn?
December, with a typical high of 32° and a low of 24°.
What is the hottest month in Roslyn?
August, with a typical high of 73° and a low of 50°. About 7 days a year reach 90°.
When is the first frost in Roslyn?
In half of years the first 32° night comes by October 6, and the last spring frost by May 9.
What is the rainiest month in Roslyn?
December, with 9.4 inches of rain and melted snow. The year totals 55 inches.
Temperatures and rainfall come from NOAA’s gridded climate normals for Roslyn itself (about a 3-mile square). Snow, frost dates and day counts come from NOAA’s weather station at Easton, WA (3 mi, frost, heat and degree days). Normals are 30-year averages, not a forecast. Source: NOAA NCEI U.S. Climate Normals, 1991–2020 and 1901–2000.