Chapter 2

Climate of Louisiana

B Brian Bucker

Introduction

The state of Louisiana can be found in the southeastern United States. It lies between the 29th and 33rd parallel north of the equator. Its northern, eastern, and western borders are surrounded by land. However, its southern border rests on the Gulf of Mexico.

The location of Louisiana places it in a moist, subtropical climate. This classification of climate tells us that Louisiana receives a steady amount of rainfall and mild to hot temperatures throughout most of the year. Also, because it is surrounded by land and water Louisiana’s climate is affected by Continental and Marine influences. North Louisiana experiences more variable changes in temperature and precipitation, while ocean currents keep conditions in southern Louisiana constant.

Winds & Air Masses

Winds are certainly a dominant force in Louisiana’s climate. The winds are responsible for the mobility of the three dominant air masses: Maritime Tropical, Maritime Polar, and Continental Polar. The winds are also responsible for bringing changes in the season and moving precipitation across the land. Louisiana is situated between the easterly and westerly wind belts. This causes westerly winds during the winter months and easterly and winds during the summer.

Temperatures & Precipitation

As mentioned before temperatures and precipitation are more variable in northern Louisiana than in Southern Louisiana. North Louisiana has an average yearly temperature of about 66 degrees Fahrenheit. However, this is only an average temperature. There are considerable differences between the average temperatures in the summer and winter months. January holds an average temperature of about 49 degrees Fahrenheit. The warmest month of the year is July. July’s average temperature is 82 degrees Fahrenheit. North Louisiana, with its temperature extremes, holds the records for the highest and lowest recorded temperatures in the state. The lowest recorded temperature ever was –16 degrees Fahrenheit in Minden, Louisiana. The highest recorded temperature ever was 114 degrees Fahrenheit in Plain Dealing, Louisiana. Both of these locations are in the northwester corner of the state.

North Louisiana’s pattern of precipitation is similar to its variable temperature patterns. Louisiana finds the majority of its precipitation occurring in the winter months while the summer months are found to be drier. The area’s average amount of precipitation is about 48 inches a year. This is considerably different from south Louisiana’s average because of its distance from the Gulf of Mexico.

Of course the biggest effect on southern Louisiana’s climate is the Gulf of Mexico. The ocean currents keep southern Louisiana from heating up and cooling off as quickly as does the northern interior. The average annual temperature for southern Louisiana is about 69 degrees Fahrenheit. January, the coldest month of the year, has average temperature of 54 degrees Fahrenheit. July’s average temperature is about 82 degrees Fahrenheit. Notice that southern and northern Louisiana’s averages in the summer months are the same, while there is a six degrees difference in the temperatures of the winter months. This is a good example of those ocean currents affecting the southern regions climate conditions.

The precipitation of southern Louisiana is rather constant throughout the year. The area’s total average rainfall amount is about 64 inches a year. There is almost a twenty inch difference between the southern and northern regions! The state’s most saturated area is the area known as the Florida Parishes. This area averages over 70 inches of rain per year!
 

Maps: precipitation of Louisiana (Courtesy of Louisiana State University)

Average temperature of Louisiana (Courtesy of Louisiana State University)

Frost Dates

Louisiana experiences freezes during the fall and winter months. It occurs when a polar air mass settles in over the state. The cool temperatures and the clear skies, which allow hot air to escape to the higher atmosphere, keep the ground at very low temperatures.

The frost dates vary throughout the different regions of the state. North Louisiana has the longest period of frost dates. The period usually begins in mid-October and lasts until the end of March.

However, in southern Louisiana the frost season is much shorter. In fact, some areas along the extreme southern coast never receive a frost all year. The frost season usually begins in early December and ends in mid-February. North Louisiana’s frost season is over twice as long as south Louisiana’s frost season!

Growing Season

So why is studying the climate of Louisiana important? Well, one of the main reasons is the growing season. The growing season is the period of time between the first and last freezes when farmers can produce their crops.

Studying the climate also allows the farmer to know what crops can be grown in certain areas.

In north Louisiana, the growing season spans from 210-230 days a year. In south Louisiana, the growing season spans from 230-290 days a year. The length of the growing season allows the farmers to determine the success of the crops. The growing season relies on warm temperatures and plenty of rainfall to produce a good crop.

Storms

North Louisiana rests on the edge of an area know as "Tornado Alley." This area describes a strip of land over the Great Plains that have a prominent amount of tornados each year. Even though Louisiana is not in the Great Plains region, it is still affected by this phenomenon. Also, because Louisiana has more hills than the Plain States, the tornados are not spotted from miles away and usually surprise people.

Tornadoes occur in Louisiana during the Spring months. When a frontal system with a cold air mass moves in over the warm air mass, the warm air rises into the cold air mass, and begins to swirl. This usually spawns a tornado. Louisiana also has tornados during the summer months, but these are usually created by Hurricanes.

Louisiana is also affected by violent sea storms called hurricanes. The hurricane season usually lasts from through November. Most hurricanes occur in the Atlantic Ocean and along its coast, but hurricanes have been found in the Gulf of Mexico many times. Louisiana has experienced hurricanes about 25 times during the 20th Century. These storms have brought coastal damage to southern Louisiana with its high winds and down-pouring rains. Northern Louisiana is usually only receives heavy rainfall from these storms.

Conclusion

From the northern border to the Gulf of Mexico, from the Mississippi River to the Texas border, Louisiana has several different regions. Louisiana also has several dominant sources that affect her climate. However, each source is unique, and they are all responsible for the climate of Louisiana.

Links

http://www.srcc.lsu.edu/LOSC/