Mosquito season in Jersey County, IL: when it starts and ends
Mosquito months in Jersey County
In a normal year mosquito season in Jersey County, IL starts around April 5 and ends around October 28, about 29 weeks.
- Jan
- Feb
- Mar
- Apr
- May
- Jun
- Jul
- Aug
- Sep
- Oct
- Nov
- Dec
What to do in Jersey County, and when
- Start tipping out standing water weekly by March 22.
- Book any yard treatment for early April, ahead of the July peak.
- Repellent can go away after October 28.
- 1 West Nile case since 2016 (last 2016): you should use repellent at dusk June to August, more so if over 60.
Jersey County against the rest of IL
Jersey County has the 42nd longest season of 102 IL counties, at 206 days against 232 in Pulaski County and 174 in Boone County. Its mean temperature is 53.5°F.
- Christian County: April 5 to October 29 (207 days, 0 WNV)
- Shelby County: April 5 to October 29 (207 days, 0 WNV)
- Calhoun County: April 6 to October 29 (206 days, 0 WNV)
- Hardin County: April 6 to October 29 (206 days, 0 WNV)
West Nile in Jersey County
From 1999 to 2025, CDC ArboNET counted 1 human West Nile case in Jersey County (0 neuroinvasive) across 1 year. The worst was 2016 with 1; the latest was 2016.
More: how the dates are worked out · when the season starts across the US.