Mosquito season in Rock Island County, IL: when it starts and ends
Mosquito months in Rock Island County
In a normal year mosquito season in Rock Island 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 Rock Island 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.
- 3 West Nile cases since 2016 (last 2023): you should use repellent at dusk June to August, more so if over 60.
Rock Island County against the rest of IL
Rock Island County has the 75th longest season of 102 IL counties, at 193 days against 232 in Pulaski County and 174 in Boone County. Its mean temperature is 50.8°F.
- Ford County: April 13 to October 23 (193 days, 1 WNV)
- McDonough County: April 13 to October 23 (193 days, 1 WNV)
- Iroquois County: April 14 to October 24 (193 days, 0 WNV)
- Woodford County: April 15 to October 25 (193 days, 3 WNV)
West Nile in Rock Island County
From 1999 to 2025, CDC ArboNET counted 12 human West Nile cases in Rock Island County (8 neuroinvasive) across 9 years. The worst was 2018 with 2; the latest was 2023.
Background: when mosquitoes go away for the winter; how the dates are worked out.