Mosquito season in St. John the Baptist Parish, LA: when it starts and ends

Mosquito months in St. John the Baptist Parish

In a normal year mosquito season in St. John the Baptist Parish, LA starts around January 28 and ends around January 1, about 48 weeks.

What to do in St. John the Baptist Parish, and when

Start tipping out standing water weekly by January 14.
Book any yard treatment for late January, ahead of the July peak.
Repellent can go away after January 1.
2 West Nile cases since 2016 (last 2025): you should use repellent at dusk May to October, more so if over 60.

St. John the Baptist Parish against the rest of LA

St. John the Baptist Parish has the 13th longest season of 64 LA counties, at 338 days against 358 in Orleans Parish and 247 in Claiborne Parish. Its mean temperature is 69.2°F.

Evangeline Parish: February 5 to January 11 (340 days, 2 WNV)
St. James Parish: January 28 to January 1 (338 days, 2 WNV)
Beauregard Parish: February 12 to January 13 (335 days, 2 WNV)
Washington Parish: February 11 to January 11 (334 days, 10 WNV)

West Nile in St. John the Baptist Parish

From 1999 to 2025, CDC ArboNET counted 6 human West Nile cases in St. John the Baptist Parish (5 neuroinvasive) across 4 years. The worst was 2002 with 3; the latest was 2025.

Background: where mosquitoes never stop; how the dates are worked out.