Grand Coulee, WA Weather & Growing Conditions

Local forecast, frost dates, hardiness zone and planting guidance for Grand Coulee, a city in Grant County, Washington.

Today

56°F

Sunny

Sunny. High near 56, with temperatures falling to around 49 in the afternoon. South wind 1 to 6 mph.

7-day forecast for Grand Coulee

When	Temp	Forecast	Wind	Precip
Today	56°F	Sunny	1 to 6 mph S	2%
Tonight	39°F	Chance Rain Showers	5 mph SE	40%
Thursday	55°F	Mostly Sunny	3 mph SE	11%
Thursday Night	38°F	Partly Cloudy	6 mph SE	8%
Friday	55°F	Mostly Cloudy	5 to 8 mph SE	8%
Friday Night	41°F	Mostly Cloudy	5 mph E	9%
Saturday	60°F	Partly Sunny	6 mph E	6%
Saturday Night	43°F	Mostly Cloudy then Slight Chance Rain Showers	5 to 8 mph SE	15%
Sunday	60°F	Slight Chance Rain Showers then Partly Sunny	8 to 16 mph SW	15%
Sunday Night	40°F	Mostly Cloudy	3 to 8 mph S	1%
Monday	57°F	Partly Sunny then Slight Chance Rain Showers	5 mph NE	15%
Monday Night	41°F	Chance Rain Showers	2 to 6 mph E	32%
Tuesday	59°F	Chance Rain Showers	3 to 8 mph SE	32%
Tuesday Night	43°F	Slight Chance Rain Showers	6 mph SE	22%

Forecast source: National Weather Service (api.weather.gov) for Grand Coulee (47.939, -119.002). Updated through the day.

Growing snapshot for Grand Coulee

Last spring frost

Apr 22

First fall frost

Oct 21

Growing season

180 days

Hardiness zone

More local growing data for Grand Coulee: nearby ZIP 99123 weather · frost dates · planting calendar · Washington frost dates

Nearby towns & communities

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Climate data from the nearest NOAA station, Coulee Dam 1 Sw, Wa (5.3 mi from Grand Coulee). Frost dates are 1991–2020 averages, not a forecast. Page updated Nov 4, 2026.