1951-1952, the most in a calendar year was in 1971, the most in a month was in March 1952, and the most in a day was on February 16, 1990. 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 in December to in July, with the diurnal temperature variation occasionally reaching in summer, still lower than much of the high desert to the east. There are 6.0 days of + highs, 65 days of + highs, 1.6 days with + lows, and 1.9 days with sub- lows annually; the temperature reaches or dips below the freezing point on 122 days, and does not rise above freezing on only 4.1 of those days. The all-time record high temperature is , which occurred on July 10 and 11, 2002, and again on July 5, 2007. The all-time record low temperature is , which occurred on January 21, 1916; the lowest temperature recorded at the airport is , which occurred on four occasions, most recently on February 7, 1989. 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. Demographics As of the census of 2010, there were 225,221 people, 90,924 households, and 51,112 families residing in the city. The population density was 2,186.6 per square mile (844.2/km). There were 102,582 housing units at an average density of 995.9 per square mile (384.5/km). The city's racial makeup was 74.2% White, 2.9% African American, 1.3% Native American, 6.3% Asian, 0.7% Pacific Islander, 10.5% some other race, and 4.2% from two or more races. Hispanic or Latino people of any race were 24.3% of the population. Non-Hispanic Whites were 62.5% of the population in 2010, down from 88.5% in 1980. At the 2010 census, there were 90,924 households, of which