Monthly weather forecast and Climate
Grand Coulee, WA US

Warmest months (with the highest average high temperature) are July and August (87°F).
The month with the lowest average high temperature is December (32°F).

The month with the highest average low temperature is July (58°F).
The coldest month (with the lowest average low temperature) is December (22°F).

The wettest month (with the highest rainfall) is December (1.5").
The driest month (with the lowest rainfall) is August (0.3").