We've seen drifts form so quickly on wind-scoured Antelope Flats near Idaho Falls that even 500 yards behind a snow plow the road surface is again buried. Rain and wind protection are a must here. And even in summer you'll want to carry something warm for evenings or unexpected clouds. If you're driving, don't expect the weather to be the same when you get out of the car as it was where you climbed in, especially if you're going to move from one elevation to another or from one mountain valley to another. That depends on you.
Spring brings snowmelt and mud to our mountain towns and early green to valley communities.
Rivers usually run big and muddy from late May through July. All this means that in early summer, the fishing isn't generally too hot, the mosquitos are swarming, and the high country is not easily reachable due to slow snowmelt and swollen, difficult creek crossings. However, the weather is pleasantly cool, and lower-elevation wildflower meadows can be breathtaking. Wildflowers burst out in the higher elevations. Down low, farmers' markets begin to fill with local produce.