Mosquito season in Monroe County, IA: when it starts and ends
Mosquito months in Monroe County
In a normal year mosquito season in Monroe County, IA starts around April 15 and ends around October 21, about 27 weeks.
- Jan
- Feb
- Mar
- Apr
- May
- Jun
- Jul
- Aug
- Sep
- Oct
- Nov
- Dec
What to do in Monroe County, and when
- Start tipping out standing water weekly by April 1.
- Book any yard treatment for mid April, ahead of the July peak.
- Repellent can go away after October 21.
- 1 West Nile case since 2016 (last 2018): you should use repellent at dusk June to August, more so if over 60.
Monroe County against the rest of IA
Monroe County has the 17th longest season of 99 IA counties, at 189 days against 198 in Des Moines County and 160 in Worth County. Its mean temperature is 50°F.
- Warren County: April 14 to October 21 (189 days, 7 WNV)
- Marion County: April 15 to October 21 (189 days, 5 WNV)
- Taylor County: April 15 to October 21 (189 days, 0 WNV)
- Jefferson County: April 15 to October 20 (188 days, 0 WNV)
West Nile in Monroe County
From 1999 to 2025, CDC ArboNET counted 4 human West Nile cases in Monroe County (2 neuroinvasive) across 4 years. The worst was 2018 with 1; the latest was 2018.
Background: when mosquitoes go away for the winter; how the dates are worked out.