Mosquito season in McDonough County, IL: when it starts and ends
Mosquito months in McDonough County
In a normal year mosquito season in McDonough County, IL starts around April 13 and ends around October 23, about 28 weeks.
- Jan
- Feb
- Mar
- Apr
- May
- Jun
- Jul
- Aug
- Sep
- Oct
- Nov
- Dec
What to do in McDonough County, and when
- Start tipping out standing water weekly by March 30.
- Book any yard treatment for mid April, ahead of the July peak.
- Repellent can go away after October 23.
- 1 West Nile case since 2016 (last 2025): you should use repellent at dusk June to August, more so if over 60.
McDonough County against the rest of IL
McDonough County has the 74th longest season of 102 IL counties, at 193 days against 232 in Pulaski County and 174 in Boone County. Its mean temperature is 50.7°F.
- Kankakee County: April 14 to October 25 (194 days, 4 WNV)
- Ford County: April 13 to October 23 (193 days, 1 WNV)
- Rock Island County: April 13 to October 23 (193 days, 3 WNV)
- Iroquois County: April 14 to October 24 (193 days, 0 WNV)
West Nile in McDonough County
From 1999 to 2025, CDC ArboNET counted 2 human West Nile cases in McDonough County (1 neuroinvasive) across 2 years. The worst was 2025 with 1; the latest was 2025.
More: how the dates are worked out · when the season starts across the US.