Mosquito season in Nassau County, FL: when it starts and ends
Mosquito months in Nassau County
In a normal year mosquito season in Nassau County, FL starts around February 4 and ends around January 2, about 47 weeks.
- Jan
- Feb
- Mar
- Apr
- May
- Jun
- Jul
- Aug
- Sep
- Oct
- Nov
- Dec
What to do in Nassau County, and when
- Start tipping out standing water weekly by January 21.
- Book any yard treatment for early February, ahead of the July peak.
- Repellent can go away after January 2.
- 4 West Nile cases since 2016 (last 2018): you should use repellent at dusk May to October, more so if over 60.
Nassau County against the rest of FL
Nassau County has the 41st longest season of 67 FL counties, at 332 days against 365 in Broward County and 281 in Gilchrist County. Its mean temperature is 69.3°F.
- Marion County: February 4 to January 3 (333 days, 2 WNV)
- Suwannee County: January 31 to December 29 (332 days, 2 WNV)
- Franklin County: February 5 to January 1 (330 days, 0 WNV)
- Jefferson County: February 4 to December 27 (326 days, 0 WNV)
West Nile in Nassau County
From 1999 to 2025, CDC ArboNET counted 6 human West Nile cases in Nassau County (3 neuroinvasive) across 3 years. The worst was 2018 with 4; the latest was 2018.
Background: where mosquitoes never stop; how the dates are worked out.