Jacksonville has a humid subtropical climate (Koppen Cfa), with mild weather during winters and hot weather during summers. High temperatures average 64 to 91 °F (18 to 33 °C) throughout the year. Highheat indices are not uncommon for the summer months in the Jacksonville area. High temperatures can reach the mid and upper 90s with heat indices of 105-115 °F. The highest temperature ever recorded in Jacksonville was 105 °F (41 °C) on July 21, 1942. It is common for thunderstorms to erupt during a typical summer afternoon. These are caused by the rapid heating of the land relative to the water, combined with extremely high humidity.
During winter, there can be hard freezes during the night. Such cold weather is usually short lived, as the city averages only 10 to 15 nights below freezing. The coldest temperature recorded in Jacksonville was 7 °F (?14 °C) on January 21, 1985, a day that still holds the record cold for many locations in the eastern half of the US. Even rarer in Jacksonville than freezing temperatures is snow. When snow does fall, it usually melts upon making contact with the ground. Most residents of Jacksonville can remember accumulated snow on only one occasion—-a thin ground cover that occurred December 23 of 1989.
Jacksonville has suffered less damage from hurricanes than most other east coast cities, although the threat does exist for a direct hit by a major hurricane. The city has only received one direct hit from a hurricane since 1871, although Jacksonville has experienced hurricane or near-hurricane conditions more than a dozen times due to storms passing through the state from the Gulf of Mexico to the Atlantic Ocean, or passing to the north or south in the Atlantic and brushing past the area. The strongest effect on Jacksonville was from Hurricane Dora in 1964, the only recorded storm to hit the First Coast with sustained hurricane force winds. The eye crossed St. Augustine with winds that had just barely diminished to 110 mph (180 km/h), making it a strong Category 2 on the Saffir-Simpson Scale. Jacksonville also suffered damage from 2008's Tropical Storm Fay which crisscrossed the state, bringing parts of Jacksonville under darkness for four days. Similarly, four years prior to this, Jacksonville was inundated by Hurricane Frances and Hurricane Jeanne, which made landfall south of the area. These tropical cyclones were the costliest indirect hits to Jacksonville. Hurricane Floyd in 1999 caused damage mainly to Jacksonville Beach. During Floyd, the Jacksonville Beach pier was completely destroyed. The rebuilt pier was later heavily damaged by Fay, but not destroyed.
Rainfall averages around 52 inches (1,300 mm) a year, with the wettest months being June through September.