Mosquito season in Tama County, IA: when it starts and ends

Mosquito months in Tama County

In a normal year mosquito season in Tama County, IA starts around April 21 and ends around October 16, about 25 weeks.

1. Jan
2. Feb
3. Mar
4. Apr
5. May
6. Jun
7. Jul
8. Aug
9. Sep
10. Oct
11. Nov
12. Dec

What to do in Tama County, and when

• Start tipping out standing water weekly by April 7.
• Book any yard treatment for late April, ahead of the July peak.
• Repellent can go away after October 16.
• 3 West Nile cases since 2016 (last 2025): you should use repellent at dusk July to August, more so if over 60.

Tama County against the rest of IA

Tama County has the 54th longest season of 99 IA counties, at 178 days against 198 in Des Moines County and 160 in Worth County. Its mean temperature is 47.4°F.

• Jones County: April 21 to October 15 (178 days, 1 WNV)
• Palo Alto County: April 21 to October 16 (178 days, 1 WNV)
• Dubuque County: April 21 to October 15 (177 days, 2 WNV)
• Ida County: April 21 to October 15 (177 days, 3 WNV)

West Nile in Tama County

From 1999 to 2025, CDC ArboNET counted 6 human West Nile cases in Tama County (3 neuroinvasive) across 4 years. The worst was 2025 with 2; the latest was 2025.

See how the dates are worked out, and when the season starts across the US.