Reno sits in the rain shadow of the Sierra Nevada mountain range. Annual rainfall averages 7.48 inches due to its low evapotranspiration. The city experiences cool to cold winters, and hot summers. Annual precipitation has ranged from 1.55 inches (39.4 mm) in 1947 to 13.23 inches (336.0 mm) in 1983. The most precipitation in one month was 5.25 inches (133.4 mm) in December 1955 and the most precipitation in 24 hours was 2.29 inches (58.2 mm) on January 21, 1943. Winter snowfall is usually light to moderate, but can be heavy some days, averaging 21.5 inches (55 cm) annually. Snowfall varies with the lowest amounts (roughly 19–23 inches annually) at the lowest part of the valley at and east of the Reno–Tahoe International Airport at 4,404 feet (1,342 m), while the foothills of the Carson Range to the west ranging from 4,700 to 5,600 feet (1,400 to 1,700 m) in elevation just a few miles west of downtown can receive two to three times as much annual snowfall. The mountains of the Virginia Range to the east can receive more summer thunderstorms and precipitation, and around twice as much annual snowfall above 5,500 feet (1,700 m). However, snowfall increases in the Virginia Range are less dramatic as elevation climbs than in the Carson Range to the west, because the Virginia Range is well within the rain shadow of the Sierra Nevada and Carson Range. The most snowfall in the city in one year was 63.8 inches (162 cm) in 1971, and the most snowfall in one month was 29.0 inches (74 cm) in March 1952.
Most rainfall occurs in winter and spring. The city has 300 days of sunshine per year. Summer thunderstorms can occur between April and October. The eastern side of town and the mountains east of Reno tend to be prone to thunderstorms more often, and these storms may be severe because an afternoon downslope west wind, called a “Washoe Zephyr”, can develop in the Sierra Nevada, causing air to be pulled down in the Sierra Nevada and Reno, destroying or preventing thunderstorms, but the same wind can push air upward against the Virginia Range and other mountain ranges east of Reno, creating powerful thunderstorms.
The monthly daily average temperature ranges from 35.3 °F (1.8 °C) in December to 74.9 °F (23.8 °C) in July, with the diurnal temperature variation reaching 40 °F (22 °C) in summer, still lower than much of the high desert to the east. There are 3.9 days of 100 °F (38 °C)+ highs, 58 days of 90 °F (32 °C)+ highs, and 2.5 nights with sub-10 °F (−12 °C) lows annually; the temperature does not rise above freezing on only 5.1 days. The all-time record high temperature is 108 °F (42 °C), which occurred on July 10 and 11, 2002, and again on July 5, 2007. The all-time record low temperature is −17 °F (−27 °C), which occurred on January 21, 1916. In addition, the region is windy throughout the year; observers such as Mark Twain have commented about the “Washoe Zephyr”, northwestern Nevada’s distinctive wind.