Mosquito season in Jo Daviess County, IL: when it starts and ends
Mosquito months in Jo Daviess County
In a normal year mosquito season in Jo Daviess County, IL starts around April 22 and ends around October 16, about 25 weeks.
- Jan
- Feb
- Mar
- Apr
- May
- Jun
- Jul
- Aug
- Sep
- Oct
- Nov
- Dec
What to do in Jo Daviess County, and when
- Start tipping out standing water weekly by April 8.
- Book any yard treatment for late April, ahead of the July peak.
- Repellent can go away after October 16.
- 1 West Nile case since 2016 (last 2016): you should use repellent at dusk July to August, more so if over 60.
Jo Daviess County against the rest of IL
Jo Daviess County has the 98th longest season of 102 IL counties, at 177 days against 232 in Pulaski County and 174 in Boone County. Its mean temperature is 47.4°F.
- Whiteside County: April 19 to October 18 (181 days, 1 WNV)
- DeKalb County: April 20 to October 18 (180 days, 6 WNV)
- Stephenson County: April 22 to October 16 (177 days, 3 WNV)
- Winnebago County: April 23 to October 16 (177 days, 11 WNV)
West Nile in Jo Daviess County
From 1999 to 2025, CDC ArboNET counted 4 human West Nile cases in Jo Daviess County (3 neuroinvasive) across 4 years. The worst was 2016 with 1; the latest was 2016.
More: how the dates are worked out · when mosquitoes go away for the winter.