Climate of Florida

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The climate of North and Central Florida is humid subtropical. South Florida has a tropical climate.^[1] There is a defined rainy season from June through September, which are the months most at risk of landfalling tropical cyclones. Between October and May, fronts regularly sweep through the state which keeps conditions dry, particularly over the peninsula. Towards the end of the dry season in the spring, brush fires become common statewide. In winters where an El Niño climate cycle exists, rainfall increases while temperatures are cooler statewide. Snow and sleet have been witnessed as early as November and as late as April, though most areas do not experience any frozen precipitation during a typical year. Easterly winds off the warm waters of the Gulf Stream running through the Florida Straits keep temperatures moderate across the southern peninsula year round.

Contents 1 Pressure 2 Wind 2.1 African dust outbreaks 3 Temperature 3.1 Winter 3.2 Summer 3.3 Records 4 Fog 5 Liquid precipitation equivalent 5.1 Averages 5.2 Extremes 5.3 Snowfall 6 Tropical cyclones 7 Affect of Southern Oscillation 8 See also 9 References

[edit] Pressure

The low pressure measured from an extratropical cyclone was 28.84 inches/976.7 hPa during the Storm of the Century (1993).^[2] 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.^[3] The highest known pressure measured statewide was 30.74 inches/1041.1 hPa in Tallahassee on February 5, 1996 and January 4, 1979.^[2]

[edit] Wind

Over the entire year, winds average out of the north across the panhandle and near Orlando, out of the west at Gainesville and Jacksonville, and generally out of the east elsewhere. During the summer months, the average wind pattern implies a surface ridge axis normally lies across central Florida, with easterly winds from Tampa southward and southwest winds across northern Florida, once Orlando is not considered for the distribution. The peak wind gust during the 1930 through 1997 period was 115 mph/100 knots at Miami International Airport during Hurricane Andrew.^[4] There are more tornados per square mile than any other state.^[5] However, these average less energy and therefore fewer deaths and property damage than are experienced by some other states. Hurricanes typically spawn tornados in their wake.

[edit] African dust outbreaks

July is the month where the tradewinds south of the northward-moving subtropical ridge expand northwestward into Florida. 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 leads 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.^[6] Over 50% of the African dust that reaches the United States affects Florida.^[7] 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.^[8] Dust events have been linked to a decline in the health of coral reefs across the Caribbean and Florida, primarily since the 1970s.^[9]

[edit] Temperature

Monthly Normal High and Low Temperatures For Various Florida Cities
City	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
Jacksonville[10]	65/43	68/45	74/50	80/56	86/64	90/70	92/73	91/73	87/70	80/61	73/51	66/44
Key West[11]	75/65	76/66	79/69	82/72	85/76	88/78	89/80	90/80	88/78	85/76	80/71	76/67
Melbourne[12]	72/51	73/53	77/57	81/61	85/67	88/71	90/73	90/73	88/72	83/67	78/60	73/53
Miami[13]	76/60	77/61	80/64	83/68	86/72	88/75	90/77	90/77	88/76	85/72	81/67	77/62
Pensacola[14]	61/43	64/46	70/51	76/58	84/66	89/72	90/74	90/74	87/70	80/60	70/50	63/45
Tallahassee[15]	64/40	67/42	73/48	80/53	87/62	91/69	91/72	91/72	88/68	81/57	72/47	66/41
Tampa[16]	71/51	72/52	77/57	82/62	88/68	90/73	90/75	90/75	89/73	84/66	77/58	72/52

The climate regime for much of the state is humid subtropical (Koppen Cfa), though portions of the Gold Coast of southeast Florida, as well as all of the Florida Keys, qualify as tropical wet-and-dry (Koppen Aw).

[edit] Winter

On average, wintertime lows dip down to near 40 degrees Fahrenheit at Tallahassee in January to 65 °F (18 °C) in Key West while daytime highs range from 64 °F (18 °C) at Tallahassee to 75 °F (24 °C) at Key West.^[17][18] Predominant easterly winds across southern Florida keep temperates moderate during the winter, as the nearby Gulf Stream modifies cooler air moving in from the northeast and east. El Niño winters tend to be cooler due to increased cloud cover, but tend to have fewer freezes.^[19]

[edit] Summer

During the summer, minima range from near 70 °F (21 °C) in northern Florida to near 80 °F (27 °C) in the Keys. High temperatures during the summer average in the lower 90s Fahrenheit statewide.^[20] Relief from the heat during the summer comes in the form of afternoon and evening thunderstorm activity, late morning and afternoon sea breezes off the relatively cooler ocean, and during the passage of a tropical cyclone. The passage of a cold front through the state is rare during the warm season.

[edit] Records

The record high temperature for the state is 109 °F (43 °C) at Monticello in 1931. The record low temperature was −2 °F (−18.9 °C) at Tallahassee in 1899.^[21]

[edit] Fog

Like the remainder of the Southeastern United States, Florida has a winter maximum in dense fog conditions. Unlike the remainder of the region, the maximum in Florida contains roughly half of the annual occurrences per year, on average. Its summer minimum is also less than the remainder of the Southeast. There has been no noticeable increase or decrease in fog across Florida, over the past several decades.^[22]

[edit] Liquid precipitation equivalent

[edit] Averages

Statewide, the highest rainfall amounts occur during the summer months. In northern Florida, there is a weak winter secondary maximum while statewide the driest months of the year are during the spring.^[20] During El Niño, Florida sees greater rainfall between November and March.^[19] Due to the lack of the secondary maximum across the peninsula, a distinct dry season is seen in the averages from winter through spring. This dry season provokes brush fires annually as temperatures rise during the late spring, before they fade during early June as the rainy season gets underway.

[edit] Extremes

The heaviest rainfall to occur in 24 hours was measured in Yankeetown during Hurricane Easy (1950), 38.70 inches/983 mm. This is also the highest known point storm total maximum related to any tropical cyclone which has impacted Florida,^[23] and by itself would be the highest known rainfall total for any month from any location within Florida. This rainfall amount remained the national 24-hour rainfall record until Tropical Storm Claudette (1979).^[24] Heavy rainfall events have fallen due to stalled fronts near the state as well, and occur during the March through May and October through November timeframe.

The wettest month recorded at a Florida climate station was during May 1891 when Gainesville, Florida received 30.90 inches/785 mm.^[25] The wettest year on record for a Florida climate station was during 1879 when 127.24 inches/3232 mm fell at Pensacola, Florida.^[26] The driest year for a climate station statewide was during 1974 when only 19.99 inches/508 mm fell at Key West.^[27]

The state of Florida is currently within a drought that began in November 2005, a month after Hurricane Wilma's passage through the state.^[28] The previous significant drought occurred in 2000, which was the state's driest year on record.^[29]

[edit] Snowfall

Main article: Snow in Florida

The earliest recorded occurrence of snow or sleet occurred in 1774.^[30] The most recent occurrence of snow was on January 3, 2008.^[31] The state record for snowfall is 5 inches (125 mm), set in northern Florida during January 1800.^[32] The earliest in the fall snow or sleet occurred was during the Late November 2006 Nor'easter on November 21 across central Florida.^[33] The latest occurrence of snow or sleet in the spring fell on April 8, 2007. A trace of snowfall has been recorded as far south as Homestead, mainly during a January 19, 1977 event.^[34]

[edit] Tropical cyclones

See also: List of Florida hurricanes

The earliest a tropical cyclone has struck the sunshine state was the Groundhog Day Tropical Storm in 1952. The latest impact was from a hurricane which struck near Tampa on December 1, 1925. The strongest hurricane to strike Florida was the Labor Day Hurricane of 1935. Hurricane Easy in 1950 produced the wettest known point total from any tropical cyclone.^[23] The record number of hurricane strikes on the state in one season is four in 2004.^[35]

[edit] Affect of Southern Oscillation

El Nino has the following affect on Florida climate: above average rainfall, northern Florida is more susceptible to severe weather; below normal temperatures, increased number of low pressure systems in the Gulf of Mexico during the winter, and "almost always" reduces the frequency of storms and hurricanes.^[36]

La Nina has the following affect: often dry conditions prevail in late fall, winter and early spring, increased risk of wildfires in spring and summer months, the temperatures average slightly above normal, and the chance of hurricane activity increases substantially.^[36]

[edit] See also

• Climate
• Climatology
• List of wettest known tropical cyclones in Florida

[edit] References

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