Nights are usually cool and temperatures may drop below freezing at higher elevations.
Thunderstorms are common in the afternoons.
Snowfall is highly variable. While the average is 150 inches per year, it is not uncommon for higher elevations to get twice that amount. At any time of year, be prepared for sudden changes. Unpredictability, more than anything else, characterizes Yellowstone's weather. Always be equipped with a wide range of clothing options.