Tulsa has a temperate climate of the humid subtropical variety with a yearly average temperature of 57 °F (14 °C) and average precipitation of just under 41 inches per year. Average monthly precipitation is lowest from December to February, and peaks dramatically in May, which averages 5.9 inches of rainfall. Early June can still be wet, but late June through the end of August is frequently dry. On average, Tulsa experiences a secondary rainfall peak in September and early October. As is typical of temperate zones, weather patterns vary by season with occasional extremes in temperature and rainfall.
Primarily in the spring and early summer months, the city is subjected to severe thunderstorms containing large hail, damaging winds, and, occasionally, tornadoes, providing the area with a disproportionate share of its annual rainfall. Severe weather is not limited to this season, however. For instance, on December 5, 1975, and on December 24, 1982, Tulsa experienced tornadoes. Due to its potential for major flooding events, the city has developed one of the most extensive flood control systems in the nation. A comprehensive flood management plan was developed in 1984 following a severe flood caused by a stalled weather front that dropped 15 in (380 mm) of rain overnight, killing 14, injuring 288, and destroying 7,000 buildings totaling $180 million in damage. In the early 1990s and again in 2000, the Federal Emergency Management Agency honored Tulsa as leading the nation in flood plain management.
Triple-digit temperatures (≥38 °C) are observed on average 11 days per year, sometimes exceeding 100 °F (38 °C) from July to early September, usually accompanied by high humidity brought in by southerly winds; The highest recorded temperature was 115 °F (46 °C) on August 10, 1936. Lack of air circulation due to heat and humidity during the summer months leads to higher concentrations of ozone, prompting the city to release “Ozone Alerts”, encouraging all parties to do their part in complying with the Clean Air Act and United States Environmental Protection Agency standards. The autumn season is usually short, consisting of pleasant, sunny days followed by cool nights. Winter temperatures, while generally mild, dip below 10 °F (−12 °C) on 3 nights, and occasionally below 0 °F (−18 °C), the most recent such occurrence being a −2 °F (−19 °C) reading on January 6, 2014. Seasonal snowfall averages 9.6 inches (24.4 cm), and only three winters on record have officially recorded a trace or no snow, the most recent being 1910–11. The lowest recorded temperature was −16 °F (−27 °C) on January 22, 1930.