Mosquito season in Warren County, IA: when it starts and ends
Mosquito months in Warren County
In a normal year mosquito season in Warren County, IA starts around April 14 and ends around October 21, about 27 weeks.
- Jan
- Feb
- Mar
- Apr
- May
- Jun
- Jul
- Aug
- Sep
- Oct
- Nov
- Dec
What to do in Warren County, and when
- Start tipping out standing water weekly by March 31.
- Book any yard treatment for mid April, ahead of the July peak.
- Repellent can go away after October 21.
- 7 West Nile cases since 2016 (last 2025): you should use repellent at dusk June to August, more so if over 60.
Warren County against the rest of IA
Warren County has the 15th 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.
- Montgomery County: April 15 to October 22 (190 days, 3 WNV)
- Polk County: April 14 to October 20 (189 days, 25 WNV)
- Marion County: April 15 to October 21 (189 days, 5 WNV)
- Monroe County: April 15 to October 21 (189 days, 1 WNV)
West Nile in Warren County
From 1999 to 2025, CDC ArboNET counted 10 human West Nile cases in Warren County (9 neuroinvasive) across 7 years. The worst was 2018 with 3; the latest was 2025.
See how the dates are worked out, and reading the West Nile counts.