Climate:
Key West claims to be the only city in the lower 48 states never to have had a frost. Because of the proximity of the Gulf
Stream in the Straits of Florida, about 12 miles south and southeast, and the tempering effects of the Gulf of Mexico to the
west and north, Key West has a notably mild, tropical climate, similar to the Caribbean islands, in which the average temperatures
during winter are about 14 degrees lower than in summer. Cold fronts are strongly modified by the warm water as they move
in from the northwest in winter. The average low and high temperatures in January are 67°F/ 75°F. There is no known record
of frost, ice, sleet, or snow in Key West. The coldest temperature ever recorded in Key West was 41°F on January 12, 1886
and on January 13, 1981. Prevailing easterly tradewinds and sea breezes suppress the usual summertime heating. The average
low and high temperatures in July are 81°F/ 90°F. The hottest temperature ever recorded in Key West was 97°F on July 19, 1880,
and on August 26, 1956.
Wet and dry seasons:
Precipitation is characterized by dry and wet seasons. The period of November through April receives abundant sunshine
and slightly less than 25 percent of the annual rainfall. This rainfall usually occurs in advance of cold fronts in a few
heavy or light showers. May through October is normally the wet season, receiving approximately 53 percent of the yearly total
in numerous showers and thunderstorms. Rain falls on most days of the wet season. Early morning is the favored time for these
showers, which is different from mainland Florida, where showers and thunderstorms usually occur in the afternoon. Summer
thunderstorms can blow up quickly and create dramatic lightning displays with very gusty winds. Boater should always check
the radar before going offshore in the rainy season. Waterspouts are numerous and common in these summer storms. Easterly
tropical waves during this season occasionally bring excessive rainfall, while infrequent hurricanes may be accompanied by
unusually heavy amounts.
