Climate of Georgia (U.S. state)

Köppen climate classification types of Georgia

The climate of Georgia is typical of a humid subtropical climate with most of the state having mild winters and hot summers. The Atlantic Ocean on the east coast of Georgia and the hill country in the north impact the state's climate.^[1] Also, the Chattahoochee River divides Georgia into separate climatic regions with the mountain region to the northwest being colder than the rest of the state, the average temperatures for that region in January and July being 39 °F (4 °C) and 78 °F (26 °C) respectively.^[2] Winter in Georgia is characterized by mild temperatures and little snowfall around the state, with colder, snowier, and icier weather more likely across northern and central Georgia. Summer daytime temperatures in Georgia often exceed 90 °F (32 °C). The state experiences widespread precipitation. Tornadoes and tropical cyclones are common.

Temperatures

Most of Georgia has a tropical climate tempered somewhat by occasional climax air masses in the winter, hot and humid summers are typical, except at the highest elevations. Weather conditions in various localities of Georgia depend on how close they are to the Atlantic Ocean or Gulf of Mexico, and their altitude. This is especially true in the mountainous areas in the northern part of the state, which are farther away from ocean waters and can be up to 4,500 feet (1,400 m) or higher above sea level. The areas near the Florida-Georgia border, extending from the Atlantic Ocean westward to the Chattahoochee River, experience the most subtropical weather, similar to that of Florida: hot, humid summers with frequent afternoon thunderstorms and mild, somewhat drier winters.

Despite having moderate weather compared to many other states, Georgia has occasional extreme weather. The highest temperature ever recorded is 112 °F (44 °C),^[3] while the lowest ever recorded is −17 °F (−27 °C).^[4] Heat waves with temperatures over 100 °F (38 °C) have been recorded.

Precipitation

Average annual precipitation for Georgia

The entire state, including the north Georgia mountains, receives moderate to heavy rain, which varies from 45 inches (1,100 mm) in central Georgia^[5] to approximately 75 inches (1,900 mm) around the Northeast part of the state.^[6] Georgia has had severe droughts in the past, especially in 2007. Tropical Storm Alberto in July 1994 looped across central Georgia, leading to 24-hour rainfall amounts exceeding 20 inches (510 mm) across central sections of the state.^[7] It also became the wettest tropical cyclone on record for the state of Georgia, eclipsing the record set in 1929.^[8] Snowfall, which occurs in most winters, increases in frequency and average amounts per year to the north.

Winter

Image of March 1993 Storm of the Century

Southern and southeast areas of the state experience snow much less frequently than other parts of Georgia. The Georgia Piedmont, sometimes referred to as the Blue Ridge province,^[9] is somewhat cooler in winter than the coastal areas. The Southern areas of the Piedmont may receive snow every other year, while areas close to the foothills get snow several times a year. The mountains of Georgia have the coolest climate and most frequent snowfall in the state, although snowfall is less than any other part of the Appalachian Mountains. The main winter weather hazard in northern Georgia is "freezing rain - or rain which freezes upon contact with the ground - which is 2 inches (5.1 cm) or more of snow falling in a 12 hour period, or 4 inches (10 cm) or more in a 24 hour period." The exception to this is the mountain areas of Fannin, Gilmer, Pickens, and other surrounding counties heavy snow is "3 inches (7.6 cm) or more of snow in a 12 hour period or 4 inches (10 cm) or more of snow in a 24 hour period". Watches for heavy snow are issued when a 50 percent or greater chance of 2 inches (5.1 cm) or more of snow falling in a 12-hour period, or 4 inches (10 cm) or more in a 24-hour period is expected. Again, there are exceptions than a trace of frozen precipitation has been recorded officially for Atlanta. The criterion for the mountain counties is "3 inches (7.6 cm) inches or more of snow in a 12 hour period or 4 inches (100 mm) or more of snow in a 24 hour period".^[10][11]

Winter weather watches are issued when there is a "50 percent or greater chance of significant and damaging accumulations of ice during freezing rain situations"; these watches are normally issued 12 to 48 hours in advance. A winter storm warning for an ice storm means that icy conditions are "occurring, imminent, or have a very high probability of occurring". These warnings are usually issued when there is an 80 percent or greater chance of meeting ice storm conditions.^[12]

Blizzards in Georgia are rare. The last blizzard the state had was in March 1993.^[13][14]

Winter in South Georgia, which lasts from December to January, is much more mild. Daytime highs range from approximately 50 °F (10 °C) in the northernmost interior areas to near 70 °F (21 °C) along the coast and in the extreme south.^[15]

Winters in Georgia are determined by the Pacific Ocean. During El Niño, the jet stream is located along the Southern U.S., allowing for colder and wetter conditions with greater snowfall. The opposite phase, La Niña, keeps the jet stream further north, thus winters are warmer and drier across Georgia.

Spring

Weather during springtime in North Georgia and the mountains changes from day to day and year to year.^[16] Early spring in the North Georgia Mountains can be very chilly during the day; average highs are near 62 °F (17 °C). The weather can be highly variable with temperatures ranging between 75 °F (24 °C) and 40 °F (4 °C). The rainiest time of the year is normally April, which can also be a windy month where daytime temperatures can rise to near 75 °F (24 °C) and evening temperatures fall to around 40 °F (4 °C)

Summer

Summers are hot and humid with temperatures in the afternoons that reach, on average, to near 90 °F (32 °C). Overnight lows fall to near 68 °F (20 °C) ^[16] and there is usually an 8 °F (4 °C) difference in temperature between the mountains and Atlanta. While humidity in North Georgia, especially in the mountains, can be high it is not as high as it is in South Georgia. Summer thunderstorms add to the humidity in the area by providing 4.5 inches (110 mm) to 5.5 inches (140 mm) of rain during the summer months.

Tropical cyclones

Tropical Storm Alberto (1994) moving into Georgia

Although Georgia experiences many tropical cyclones,^[17] it only rarely experiences a direct hurricane strike due to its fairly small coastline. The last hurricane to directly affect the Georgia coastline was Hurricane David in 1979. The last major hurricane (Category 3 or higher) to hit the Georgia coast directly was in 1898. More common are hurricanes which strike the Florida Panhandle, weaken over land, and bring tropical storm or hurricane-force winds and heavy rain to the Georgia interior (especially the southwestern areas), as well as hurricanes that come close to the Georgia coastline, brushing the coast on their way up to hit the Carolinas.

Tornadoes

Image of a tornado

Georgia is one of the leading states in incidents of tornadoes though they are rarely stronger than F1 .^[18] Southwestern and northern sections of the state have historically reported the largest amount of tornadoes.^[19] The areas closest to the Florida border report F0 and F1 tornadoes associated with summer afternoon thunderstorms. However, tornadoes of F3 intensity or greater within Georgia are uncommon, with three events reported on average each year.^[20]

Fall

Georgia's autumns are normally sunny and cool.^[21] September and October, the driest months of the year, qualify as "Indian Summer" weather with temperatures that are near 78 °F (26 °C) during the daytime. At night, the temperature drops to near 50 °F (10 °C). It is much cooler in November with an average high of 62 °F (17 °C) and low of 36 °F (2 °C). The first freeze of the year normally falls within November, except in the northern mountains, where it occurs in October.^[16]

Statistics for selected cities

See also

• List of wettest known tropical cyclones in Georgia

Notes

References

External links

• Georgia Tornadoes