Southwestern Idaho in September

May through September gives you the best weather without the winter road closures. July and August get hot — we're talking 95°F in the valleys — but the high desert cools down at night. Spring brings wildflowers to the Owyhee Canyonlands, usually peaking in late May. The hot springs feel perfect when there's still snow on the distant peaks. September might be the sweet spot: warm days, cool nights, and most of the tourists have gone home. Winter shuts down access to many hot springs, and some back roads become impassable. But if you can handle the cold, soaking in 104°F water while snow falls around you hits different.