Grand Coulee, WA Weather & Growing Conditions
Local forecast, frost dates, hardiness zone and planting guidance for Grand Coulee, a city in Grant County, Washington.
This Afternoon
82°F
Mostly Sunny
Mostly sunny, with a high near 82. Southwest wind around 5 mph.
7-day forecast for Grand Coulee
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| This Afternoon | 82°F | Mostly Sunny | 5 mph SW | 0% |
| Tonight | 56°F | Mostly Clear | 5 mph S | 0% |
| Sunday | 85°F | Sunny | 5 mph SE | 0% |
| Sunday Night | 56°F | Partly Cloudy | 3 mph E | 0% |
| Monday | 86°F | Sunny | 2 to 6 mph SE | 0% |
| Monday Night | 59°F | Partly Cloudy | 1 to 6 mph S | 0% |
| Tuesday | 82°F | Mostly Sunny | 1 to 7 mph W | 0% |
| Tuesday Night | 55°F | Partly Cloudy | 3 to 7 mph SW | 0% |
| Wednesday | 76°F | Mostly Sunny | 3 to 9 mph SW | 0% |
| Wednesday Night | 53°F | Partly Cloudy | 3 to 9 mph W | 1% |
| Thursday | 73°F | Partly Sunny | 5 mph NW | 6% |
| Thursday Night | 53°F | Mostly Cloudy | 5 mph NW | 11% |
| Friday | 71°F | Partly Sunny | 5 to 8 mph NW | 12% |
| Friday Night | 50°F | Mostly Cloudy | 8 mph NW | 14% |
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
7a
More local growing data for Grand Coulee: nearby ZIP 99123 weather · frost dates · planting calendar · Washington frost dates
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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 Sep 20, 2026.