Little Rock has a humid subtropical climate (Köppen Cfa), with hot, usually humid summers, but subject to drought, primarily in late summer. According to the Trewartha climate classification system, Little Rock is subtropical because nine of its months exceed 50 °F (10 °C) in average temperature. Summers are usually hot, occasionally extremely hot; winters are short and cool, but with marked temperature variations, as the area is subject to alternating incursions of warm, moist air from the Gulf of Mexico (possibly producing daily high temperatures in the 70s F.) and cold, dry air from Canada (possibly producing daily high temperatures below freezing, 32 F., even in the 20s F.). The Little Rock area has nearly 50 inches of precipitation per year, on average. Little Rock experiences a prolo