What is the hottest month in Cosmopolis?

August is the warmest month in Cosmopolis, with an average high of 69.3°F.

What is the coldest month in Cosmopolis?

December is the coldest month in Cosmopolis, with an average low of 36.5°F.

What month does Cosmopolis get the most rain?

January is typically the wettest month in Cosmopolis, with about 13.93 inches of precipitation.

What plant hardiness zone is Cosmopolis in?

Cosmopolis is approximately in USDA plant hardiness Zone 9a, based on the average annual extreme minimum temperature.

Cosmopolis, WA

Climate overview — based on NOAA 1991-2020 normals from ABERDEEN, WA US.

Csb Warm-summer Mediterranean climate 9a USDA hardiness Zone 9a

Year-round temperatures (°F)

Avg high Avg low

Climate summary

Cosmopolis has an annual average temperature of 51.3°F with about 84.9 inches of precipitation per year and 0.5 inches of snow. The warmest month is August (average high 69.3°F), and the coldest is December (average low 36.5°F). January is typically the wettest month (13.93 in) and July the driest (0.91 in). Snow typically falls from March through November.

Pleasant months

3 / 12

avg high 65–80°F, low ≥ 50°F

Annual swing

20.1°F

warmest to coldest month

Heating need

4,920

HDD/yr

Cooling need

CDD/yr

Best time to visit Cosmopolis

Full guide →

Climate change signal

All-time records →

22 of 366 (6%) of Cosmopolis's all-time daily heat records have been set since 2015. If records were spread evenly across the station's history, only about 5% would fall in any given decade.

1890s		27
1900s		47
1910s		24
1920s		22
1930s		39
1940s		37
1950s		30
1960s		32
1970s		17
1980s		19
1990s		25
2000s		16
2010s		25
2020s		6

Bars: number of all-time daily heat records still standing that were set in each decade.

Monthly averages

Month	Avg High	Avg Low	Avg Temp	Precipitation	Snow	Rainy days
January	47.8°F	37.3°F	42.5°F	13.93 in	—	22
February	50.3°F	36.7°F	43.5°F	8.58 in	0.1 in	19
March	53.3°F	38.4°F	45.8°F	9.76 in	0.2 in	22
April	56.6°F	41.1°F	48.8°F	6.28 in	—	19
May	61.4°F	46.6°F	54.0°F	3.46 in	—	14
June	64.7°F	51.2°F	58.0°F	2.40 in	—	12
July	68.2°F	54.2°F	61.2°F	0.91 in	—	7
August	69.3°F	54.4°F	61.8°F	1.52 in	—	7
September	68.7°F	51.1°F	59.9°F	2.73 in	—	9
October	61.0°F	44.8°F	52.9°F	8.27 in	—	18
November	52.3°F	39.6°F	45.9°F	13.72 in	0.2 in	22
December	47.0°F	36.5°F	41.7°F	13.38 in	—	23