The climate of the north and central parts of the US state of Florida is humid subtropical. South Florida has a tropical climate. There is a defined rainy season from May through October when air mass thundershowers that build in the heat of the day drop heavy but brief summer rainfall.
In October, the dry season sets in across much of Florida (starting early in the month in northern Florida and near the end of the month in deep southern Florida) and lasts until late April most years. Fronts from mid-latitude storms north of Florida occasionally pass through northern and central parts of the state which bring light and brief winter rainfall. Mid and late winter can become severely dry in Florida. In some years the dry season becomes quite severe and water restrictions are imposed to conserve water. While most areas of Florida do not experience any type of frozen precipitation, northern Florida can see fleeting snow or sleet a few times each decade.
The USDA Hardiness Zones for the state range from Zone 8A (10°F to 15°F) in the extreme northwestern panhandle, to Zone 11B (45°F to 50°F) in the lower Florida Keys.
The Gulf Stream running through the Florida Straits and then north of the Florida East Coast keeps temperatures moderate a few miles inland from around Stuart on the east coast to Ft. Myers on the west side of the state year-round, with few extremes in temperature. The tropical ocean current also provides warm sea surface temperatures, giving Florida beaches the warmest ocean surf waters on the United States mainland. Florida's geography also makes it vulnerable to the effects of climate change, both in the intensification of extreme weather such as intensified hurricanes as well as coastal flooding and other effects of sea level rise.
Pressure
The low pressure measured from an extratropical cyclone was 28.84 inches/976.7 hPa during the Storm of the Century (1993). From a tropical cyclone, the lowest pressure measured was 26.35 inches/892 hPa in the Florida Keys during the Labor Day Hurricane of 1935. The highest known pressure measured statewide was 30.74 inches/1041.1 hPa in Tallahassee on February 5, 1996, and January 4, 1979.
Wind
Over the winter prevailing winds are out of the north across the panhandle south to near Orlando, but are variable in the rest of the state. The summer season sees generally east and southeast winds across the peninsula. During the summer months, the average wind pattern implies a surface ridge axis which normally lies across central Florida, with easterly winds from Tampa southward and southwest winds across northern Florida. The peak wind gust during the 1930 through 1997 period was at Miami International Airport during Hurricane Andrew.
African dust outbreaks
In July the trade winds south of the northward-moving subtropical ridge expand northwestward into Florida. On occasion, dust from the Sahara moving around the southern periphery of the ridge moves into the state, suppressing rainfall and changing the sky from a blue to a white appearance and leading to an increase in red sunsets. Its presence negatively impacts air quality across the Southeastern United States during the summer, by adding to the count of airborne particulates. This is in sharp contrast to the normally clean air over Florida and the southeastern USA, which on average is the cleanest air in the USA. Over 50% of the African dust that reaches the United States affects Florida. Since 1970, dust outbreaks have worsened due to periods of drought in Africa. There is a large variability in the dust transport to the Caribbean and Florida from year to year. Dust events are possibly linked to a decline in the health of coral reefs across the Caribbean and Florida, primarily since the 1970s.
Winter
On average, Florida has the mildest winters in the Continental United States. Average lows range from in Key West to nearly degrees at Tallahassee, while daytime highs range from at Tallahassee to at Miami. Predominant tropical easterly winds across central and southern Florida keep temperatures warm during the winter. Occasional strong cold fronts move southward down the peninsula with freezing or near-freezing temperatures on a few nights into inland areas of central Florida every few years. A few times each decade Miami might see a winter nightfall below . El Niño winters tend to be cooler due to increased cloud cover, but tend to have fewer freezes.