Idaho has a relatively dry summer, but the rest of the year has high precipitation. The wet season lasts nearly seven and a half months, making it the bulk of the year. It’s common for areas very close to the Pacific to experience lengthy, light precipitation.
From mid-October to the first day of June, Idaho experiences a high amount of rainy days. The wettest month is December, with an average of 8.1 days experiencing rain. This metric counts any days with 0.04 inches of precipitation or more and uses Boise as an example.
If you’re trying to avoid the rain, you should visit during the summer. June, July, and August see the lowest rainfall and the highest temperatures. September and June have lower temperatures than the two months between them, with equal precipitation.