Mosquito season in Montgomery County, IL: when it starts and ends
Mosquito months in Montgomery County
In a normal year mosquito season in Montgomery County, IL starts around April 2 and ends around November 2, about 31 weeks.
- Jan
- Feb
- Mar
- Apr
- May
- Jun
- Jul
- Aug
- Sep
- Oct
- Nov
- Dec
What to do in Montgomery County, and when
- Start tipping out standing water weekly by March 19.
- Book any yard treatment for early April, ahead of the July peak.
- Repellent can go away after November 2.
- No West Nile cases since 2016, so bites in Montgomery County are a nuisance; check window screens.
Montgomery County against the rest of IL
Montgomery County has the 22nd longest season of 102 IL counties, at 214 days against 232 in Pulaski County and 174 in Boone County. Its mean temperature is 55.2°F.
- Randolph County: April 1 to November 1 (214 days, 1 WNV)
- Lawrence County: April 2 to November 1 (214 days, 0 WNV)
- St. Clair County: March 31 to October 30 (213 days, 18 WNV)
- Marion County: April 2 to November 1 (213 days, 3 WNV)
West Nile in Montgomery County
From 1999 to 2025, CDC ArboNET counted 5 human West Nile cases in Montgomery County (3 neuroinvasive) across 2 years. The worst was 2002 with 4; the latest was 2008.
Background: when mosquitoes go away for the winter; how the dates are worked out.