Yellowstone National Park, Wyoming, Idaho, Montana, United States

Climate
Yellowstone climate is greatly influenced by altitude, with lower elevations generally found to be warmer year round. The record high temperature was 99 °F (37 °C) in 2002, while the coldest temperature recorded is −66 °F (−54 °C) in 1933. During the summer months of June through early September, daytime highs are normally in the 70 to 80 °F (21 to 27 °C) range, while nighttime lows can go to below freezing (0 °C)—especially at higher altitudes. Summer afternoons are frequently accompanied by thunderstorms. Spring and fall temperatures range between 30 and 60 °F (-1 and 16 °C) with cold nights in the teens to single digits (−5 to −20 °C). Winter in Yellowstone is very cold with high temperatures usually between zero to 20 °F (−20 to −5 °C) and nighttime temperatures below zero °F (−20 °C) for most of the winter.
Precipitation in Yellowstone is highly variable and ranges from 15 inches (380 mm) annually near Mammoth Hot Springs, to 80 inches (2,000 mm) in the southwestern sections of the park. The precipitation of Yellowstone is greatly influenced by the moisture channel formed by the Snake River Plain to the west that was, in turn, formed by Yellowstone itself. Snow is possible in any month of the year, with averages of 150 inches (3,800 mm) annually around Yellowstone Lake, to twice that amount at higher elevations.
Tornadoes in Yellowstone are rare; however, on July 21, 1987, the most powerful tornado recorded in Wyoming touched down in the Teton Wilderness of Bridger−Teton National Forest and hit Yellowstone National Park. Called the Teton–Yellowstone tornado, it was classified as an F4, with wind speeds estimated at between 207 and 260 miles per hour (333 and 420 km/h). The tornado left a path of destruction 1 to 2 miles (1.6 to 3.2 km) wide, and 24 miles (39 km) long, and leveled 15,000 acres (6,100 ha; 23 sq mi) of mature pine forest.