thunderstorms. Spring and fall temperatures range between with nights in the teens to single digits (−5 to −20 °C). Winter in Yellowstone is accompanied by high temperatures usually between zero and 20 °F (−20 to −5 °C) and nighttime temperatures below 0 °F (−18 °C) for most of the winter. Precipitation in Yellowstone is highly variable and ranges from annually near Mammoth Hot Springs, to 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, but most common between November and April, with averages of annually around Yellowstone Lake, to twice that amount at higher elevations. The climate at Yellowstone Lake is classified as subarctic (Dfc), according to Köppen-Geiger climate classification, while at the park headquarters, the classification is humid continental (Dfb). 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 . The tornado left a path of destruction wide, and long, and leveled of mature pine forest. In June 2022, the park closed entrances and evacuated visitors after experiencing record-level rainfall and flooding that caused multiple road and bridge failures, power outages, and mudslides. A combination of heavy rain and rapid snow melt resulted in the Yellowstone River rising to a new record height at , breaking a previous record of set in 1918. Flooding on the Lamar River reached , beating a 1996 record of . Damage from the flooding includes washed out roads and bridges, and damage to infrastructure systems including electricity, water and wastewater systems. It's unlikely that the park will be able to reopen the north entrance by Gardiner, MT, or the northeast entrance near Cooke City, MT, during the 2022 season. The park partially reopened Wednesday, June 22, after a 9-day closure. To limit the nearly one million visitors per month that visit in the summer, the park has restricted entry to cars based on license plates. Cars with license plates ending in even numbers can enter on even-numbered dates, and plates ending in odd numbers can enter on odd-numbered dates.