When to Go
Rainier is the Puget Sound's weather vane: if you can see it, skies will be clear. Visitors are most likely to see the summit July through September. Crowds are heaviest in summer, too, meaning the parking lots at Paradise and Sunrise often fill before noon, campsites are reserved months in advance, and other lodgings are reserved as much as a year ahead.
True to its name, Paradise is often sunny during periods when the lowlands are under a cloud layer. The rest of the year, Rainier's summit gathers flying-saucer-like lenticular clouds whenever a Pacific storm approaches; once the peak vanishes from view, it's time to haul out rain gear. The rare periods of clear winter weather bring residents up to Paradise for cross-country skiing.