Mosquito season in Gallatin County, IL: when it starts and ends
Mosquito months in Gallatin County
In a normal year mosquito season in Gallatin County, IL starts around March 26 and ends around November 5, about 32 weeks.
- Jan
- Feb
- Mar
- Apr
- May
- Jun
- Jul
- Aug
- Sep
- Oct
- Nov
- Dec
What to do in Gallatin County, and when
- Start tipping out standing water weekly by March 12.
- Book any yard treatment for late March, ahead of the July peak.
- Repellent can go away after November 5.
- No West Nile cases since 2016, so bites in Gallatin County are a nuisance; check window screens.
Gallatin County against the rest of IL
Gallatin County has the 3rd longest season of 102 IL counties, at 224 days against 232 in Pulaski County and 174 in Boone County. Its mean temperature is 56.8°F.
- Pulaski County: March 23 to November 10 (232 days, 0 WNV)
- Saline County: March 26 to November 6 (225 days, 0 WNV)
- Madison County: March 27 to November 6 (224 days, 9 WNV)
- Union County: March 29 to November 8 (224 days, 0 WNV)
West Nile in Gallatin County
From 1999 to 2025, CDC ArboNET counted 2 human West Nile cases in Gallatin County (1 neuroinvasive) across 2 years. The worst was 2015 with 1; the latest was 2015.
More: how the dates are worked out · when the season starts across the US.