Cosmopolis, WA Weather & Growing Conditions
Local forecast, frost dates, hardiness zone and planting guidance for Cosmopolis, a city in Grays Harbor County, Washington.
Tonight
51°F
Mostly Cloudy
Mostly cloudy, with a low around 51. West northwest wind around 2 mph.
7-day forecast for Cosmopolis
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| Tonight | 51°F | Mostly Cloudy | 2 mph WNW | 0% |
| Saturday | 68°F | Mostly Cloudy | 0 to 6 mph WNW | 1% |
| Saturday Night | 49°F | Mostly Cloudy | 0 to 6 mph NW | 0% |
| Sunday | 70°F | Mostly Sunny | 0 to 7 mph NW | 0% |
| Sunday Night | 50°F | Partly Cloudy | 1 to 7 mph WNW | 0% |
| Monday | 69°F | Partly Sunny | 1 to 8 mph WNW | 0% |
| Monday Night | 50°F | Partly Cloudy | 2 to 8 mph NW | 0% |
| Tuesday | 66°F | Partly Sunny | 1 to 8 mph NW | 1% |
| Tuesday Night | 49°F | Mostly Cloudy | 1 to 8 mph NW | 4% |
| Wednesday | 67°F | Partly Sunny | 1 to 5 mph NNE | 4% |
| Wednesday Night | 51°F | Mostly Cloudy | 1 to 5 mph N | 11% |
| Thursday | 68°F | Partly Sunny then Slight Chance Light Rain | 2 to 6 mph ENE | 15% |
| Thursday Night | 51°F | Chance Light Rain | 2 to 6 mph W | 28% |
| Friday | 64°F | Slight Chance Light Rain | 3 to 7 mph WSW | 24% |
Forecast source: National Weather Service (api.weather.gov) for Cosmopolis (46.954, -123.773). Updated through the day.
Growing snapshot for Cosmopolis
Last spring frost
Mar 29
First fall frost
Nov 15
Growing season
234 days
Hardiness zone
8b
More local growing data for Cosmopolis: nearby ZIP 98520 weather · frost dates · planting calendar · Washington frost dates
Nearby towns & communities
Aberdeen
Aberdeen Gardens
Amanda Park
Brady
Central Park
Cohassett Beach
Copalis Beach
Elma
Grayland
Hogans Corner
Hoquiam
Humptulips
Malone
Markham
McCleary
Moclips
Montesano
Neilton
Oakville
Ocean City
Ocean Shores
Ocosta
Oyehut
Pacific Beach
Porter
Qui-nai-elt Village
Santiago
Satsop
Taholah
Westport
Climate data from the nearest NOAA station, Aberdeen, Wa (1.6 mi from Cosmopolis). Frost dates are 1991–2020 averages, not a forecast. Page updated Sep 19, 2026.