Geographic Basics - Climate, Flood, Wind and Termites

Patricia Skinner, Reichel, Claudette Hanks, Henderson, Gregg  |  1/1/2007 11:58:00 PM

climate zone map

Climate:

Most of Louisiana is in the hot, humid climate region.1

A hot-humid climate is defined as a region that receives more than 20 inches of annual rainfall and where one or both of the following occur:

  • A 67°F or higher temperature for 3,000 or more hours during the warmest six consecutive months of the year; or

  • A 73°F or higher temperature for 1,500 or more hours during the warmest six consecutive months of the year.

This zone corresponds to the U.S. Dept. of Energy (DOE) Climate Zones 1A + 2A + 3A, as indicated below the “Warm-Humid” line. (“A” represents the “moist” portion of the DOE temperature zones.) South Louisiana is in DOE climate zone 2A; the north half of La. is in Zone 3A.

Southeast Louisiana and coastal areas are in an extreme annual rainfall region (more than 60 inches). The remainder of Louisiana is in a high annual rainfall region (40-60 inches).

New Orleans has 2,655 cooling degree days (a measure of how hot a climate is), 1,513 heating degree days (a measure of how cold a climate is) and 62 inches average annual rainfall. Shreveport has 2,368 cooling degree days, 2,264 heating degree days and 46 inches average annual rainfall.

Northeast Louisiana is in the mixed, humid climate region.1

A mixed-humid climate is defined as a region that receives more than 20 inches of annual precipitation, has less than 5,400 heating degree days (65°F basis), and where the average monthly outdoor temperature drops below 45°F (7°C) during the winter months.

This zone corresponds with DOE Climate Zone 4A + 3A above the ”Warm-Humid” line. The northeastern corner of La. is in DOE Zone 3A above the Warm-Humid line.

Lake Providence in northeast La. has 2518 heating degree days, 2250 cooling degree days and 55 inches average annual rainfall.

Wind and Flood Hazards:

South Louisiana is in a hurricane zone. The closer to the gulf, the higher the wind speed risk. Tornadoes are common in North Louisiana and along the edge of hurricanes in the southern parishes.

Roughly 30% of Louisiana’s land mass lies in Special Flood Hazards Areas (SFHAs). Some of the southern-most parishes are entirely flood prone. Flood patterns change, and areas not in a designated SFHA have flooded. Protecting homes in levee-protected areas is highly recommended, though not generally required by ordinances.

For more detailed discussions of Louisiana’s exposure to flood and wind hazards and how to protect homes from these hazards, see our channels "Your Wind Zone" and "Your Flood Zone" found under  "Getting a Building Permit" in the "Laws, Licenses & Permits" section.

Termites:

Subterranean termites (native and Formosan) usually make their nests in the ground and create passageways to sources of food (cellulose) and moisture (leaks and condensation). They break into houses through construction elements and gaps as small as 1/32 of an inch.

The Formosan subterranean termite is the most destructive insect in the United States. It can cause major structural damage to a home in six months and almost complete destruction in two years. This species is a serious threat in South Louisiana and has been found in isolated cases in northern areas of the state. To reach cellulose (wood, paper) or a water source, they can chew through and destroy many non-cellulose materials, such as electric lines, plastics, mortar, plaster, rubber insulation, stucco, thin sheets of soft metal, neoprene and seals on water lines. Unprotected foam insulation can become a hidden superhighway for termites.

For additional information on designing and building to reduce termite problems, see "Termites" in the Stronger, Safer, Smarter section of this Design and Construction Web site.

1 Based upon hygro-thermal regions as defined in Builder’s Guide to Hot-Humid Climates by Joseph Lstiburek, 2005 edition.

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