Louisiana has a relatively constant semitropical climate. Rainfall and humidity decrease, and daily temperature variations increase, with distance from the Gulf of Mexico. The normal daily temperature in New Orleans is 68°F (20°C), ranging from 52°F (11°C) in January to 82°F (28°C) in July. The all-time high temperature is 114°F (46°C), recorded at Plain Dealing on 10 August 1936; the all-time low, –16°F (–27°C), was set at Minden on 13 February 1899. New Orleans has sunshine 60% of the time, and the average annual rainfall (1971–2000) was 64.2 in (163 cm). Snow falls occasionally in the north, but rarely in the south.

Prevailing winds are from the south or southeast. During the summer and fall, tropical storms and hurricanes frequently batter the state, especially along the coast. Tropical Storm Allison (June 2001) caused severe flooding in coastal regions. Among the most severe hurricanes in recent decades were Audrey, which entered Cameron Parish on 28 June 1957, causing 400–500 deaths and property damage of $150 million; Betsy, which entered the coast near Grand Isle on 9 September 1965, causing 58 deaths and damages of $1.2 billion; and Andrew, which landed on 25 August 1992 after devastating southern Florida two days earlier.