Cosmopolis, WA climate
Cosmopolis has mild winters and cool summers, with plenty of rain. A typical July afternoon reaches 69°, a January night drops to 36°, and snow is almost unheard of.
NOAA 1991-2020 climate normals Updated once a decadeWhat a year in Cosmopolis feels like
Winter
Spring
Summer
Fall
Cosmopolis 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° | 36° | 13.0" | 0 | 22 | 0 | 37° – 46° |
| February | 50° | 35° | 8.1" | 0.1" | 19 | 0 | 37° – 49° |
| March | 53° | 37° | 9.2" | 0.2" | 22 | 0 | 42° – 50° |
| April | 57° | 39° | 6.1" | 0 | 19 | 0 | 44° – 53° |
| May | 62° | 45° | 3.4" | 0 | 14 | 0 | 50° – 57° |
| June | 66° | 49° | 2.4" | 0 | 12 | 0 | 54° – 60° |
| July | 69° | 52° | 0.9" | 0 | 7 | 0 | 58° – 64° |
| August | 71° | 52° | 1.6" | 0 | 7 | 0 | 59° – 64° |
| September | 69° | 48° | 2.9" | 0 | 9 | 0 | 56° – 62° |
| October | 60° | 43° | 8.1" | 0 | 18 | 0 | 49° – 57° |
| November | 52° | 38° | 13.0" | 0.2" | 22 | 0 | 41° – 50° |
| December | 47° | 36° | 12.5" | 0 | 23 | 0 | 37° – 44° |
| Year | 59° | 42° | 81.2" | 0.5" | 192 | 1 |
“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 Cosmopolis
Cosmopolis gets 81 inches of rain and melted snow a year. November is the wettest month and July the driest. Rain or snow falls on about 192 days a year.
About 234 frost-free days a year
In half of years the last 32° night comes by March 29 and the first one by November 15. That leaves about 234 frost-free days for gardens, longer than 87% of U.S. towns.
Heating and cooling a home in Cosmopolis
Engineers use “degree days” to estimate how hard a furnace or air conditioner works. In Cosmopolis, 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 Cosmopolis 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 Cosmopolis averaged 1.3° warmer than the 1900s. The biggest change is in January (+2.9°). The shift is larger than in 53% of U.S. towns.
Change by month1991–2020 average minus 1901–2000 average, at Cosmopolis’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°. August is the most reliable, staying within 5°.
Common questions about Cosmopolis’s climate
What is the coldest month in Cosmopolis?
February, with a typical high of 50° and a low of 35°.
What is the hottest month in Cosmopolis?
August, with a typical high of 71° and a low of 52°. About 2 days a year reach 90°.
How much snow does Cosmopolis get?
Almost none. A normal year brings 0.5 inches.
When is the first frost in Cosmopolis?
In half of years the first 32° night comes by November 15, and the last spring frost by March 29.
What is the rainiest month in Cosmopolis?
November, with 13.0 inches of rain and melted snow. The year totals 81 inches.
Temperatures and rainfall come from NOAA’s gridded climate normals for Cosmopolis itself (about a 3-mile square). Snow, frost dates and day counts come from NOAA’s weather station at Aberdeen, WA (3 mi) away. Normals are 30-year averages, not a forecast. Source: NOAA NCEI U.S. Climate Normals, 1991–2020 and 1901–2000.