Louisiana’s climate is classified as humid subtropical, heavily influenced by its position along the Gulf of Mexico. The state is frequently bathed in warm, moist air originating from the Gulf, which drives its weather patterns. Determining a single “average” temperature is complicated because the weather varies significantly over the course of a year and across its diverse geographical regions.
The Statewide Annual Mean
The most direct answer to Louisiana’s average temperature is the statewide annual mean, calculated over multi-decade periods. This figure typically falls within the range of 66°F to 69°F. The overall mean temperature masks substantial differences between the northernmost parishes and the southern coast. For example, far northern areas average closer to 64°F annually, while the extreme southeast, near the Mississippi River Delta, averages around 71°F.
Seasonal Temperature Fluctuations
Louisiana experiences long, hot summers and short, mild winters. The warm season is extensive, typically lasting from late May through late September. During the peak summer months of July and August, average daily high temperatures often exceed 90°F. Overnight low temperatures frequently remain above 70°F, preventing significant cooling and creating persistently warm conditions.
The cool season generally spans December through February, with January being the coldest month. Statewide average temperatures settle between 50°F and 53°F during this time. Average winter high temperatures are often in the low to mid-60s, while lows commonly drop into the 40s. The Gulf’s proximity prevents sustained periods of severe cold, resulting in a mild winter characterized by short-lived cold snaps.
Key Geographic Variations
The influence of the Gulf of Mexico creates a temperature difference between Northern and Southern Louisiana. Coastal parishes benefit from the Gulf’s moderating effect, resulting in milder winters and slightly lower maximum summer temperatures compared to inland regions. Southern Louisiana’s average winter high is around 66°F, with lows near 46°F.
Northern Louisiana, farther from the Gulf, experiences greater temperature variability and a more continental climate. In the winter, northern regions average a high of about 59°F and a low near 37°F, making them noticeably cooler than the south. Cold fronts frequently push temperatures below 20°F in the north, a rarity for the coastal south. Summer maximum temperatures in the north can also climb above 105°F.
Beyond Air Temperature: Humidity and the Heat Index
Simple air temperature readings do not fully capture the sensation of heat in Louisiana, where high humidity is a defining characteristic of the climate. Louisiana’s location ensures a constant supply of moisture, resulting in high annual relative humidity levels, often averaging between 72% and 78%. This moisture content significantly impacts how the human body perceives temperature.
The Heat Index is a calculated value that combines the air temperature and the relative humidity to determine the “feels like” temperature. When the air is saturated with moisture, the body’s natural cooling mechanism—evaporation of sweat—is severely inhibited. Consequently, an air temperature of 90°F can easily translate into a Heat Index of 105°F or higher, a level often defined as extreme heat. The south’s high humidity contributes to elevated heat indexes, particularly during the summer months.