Summers are hot, with daytime temperatures in the 90s F (32-37 C) and low humidity in June and July. Winter temperatures often fall below freezing at night, with highs 40-60 F (4-15 C) in December and January. The summer rainy season is between late June and early September. The rain is often accompanied by severe thunder and lightning storms that can cause flash floods. Precipitation, including snow, averages about 20 inches (51 cm) per year.