Mosquito season in Carroll County, IA: when it starts and ends
Mosquito months in Carroll County
In a normal year mosquito season in Carroll County, IA starts around April 20 and ends around October 18, about 26 weeks.
- Jan
- Feb
- Mar
- Apr
- May
- Jun
- Jul
- Aug
- Sep
- Oct
- Nov
- Dec
What to do in Carroll County, and when
- Start tipping out standing water weekly by April 6.
- Book any yard treatment for mid April, ahead of the July peak.
- Repellent can go away after October 18.
- 3 West Nile cases since 2016 (last 2025): you should use repellent at dusk June to August, more so if over 60.
Carroll County against the rest of IA
Carroll County has the 45th longest season of 99 IA counties, at 181 days against 198 in Des Moines County and 160 in Worth County. Its mean temperature is 48.3°F.
- Iowa County: April 19 to October 17 (181 days, 0 WNV)
- Story County: April 19 to October 17 (181 days, 8 WNV)
- Greene County: April 20 to October 17 (180 days, 2 WNV)
- Monona County: April 20 to October 17 (180 days, 2 WNV)
West Nile in Carroll County
From 1999 to 2025, CDC ArboNET counted 11 human West Nile cases in Carroll County (6 neuroinvasive) across 7 years. The worst was 2025 with 3; the latest was 2025.
More: how the dates are worked out · when the season starts across the US.