Mosquito season in Polk County, NE: when it starts and ends
Mosquito months in Polk County
In a normal year mosquito season in Polk County, NE starts around April 16 and ends around October 21, about 27 weeks.
- Jan
- Feb
- Mar
- Apr
- May
- Jun
- Jul
- Aug
- Sep
- Oct
- Nov
- Dec
What to do in Polk County, and when
- Start tipping out standing water weekly by April 2.
- Book any yard treatment for mid April, ahead of the July peak.
- Repellent can go away after October 21.
- 5 West Nile cases since 2016 (last 2025): you should use repellent at dusk June to August, more so if over 60.
Polk County against the rest of NE
Polk County has the 24th longest season of 93 NE counties, at 188 days against 200 in Richardson County and 127 in Sioux County. Its mean temperature is 50.5°F.
- Nemaha County: April 15 to October 20 (188 days, 3 WNV)
- Hitchcock County: April 16 to October 21 (188 days, 3 WNV)
- Johnson County: April 16 to October 20 (187 days, 0 WNV)
- Saline County: April 17 to October 21 (187 days, 3 WNV)
West Nile in Polk County
From 1999 to 2025, CDC ArboNET counted 38 human West Nile cases in Polk County (10 neuroinvasive) across 12 years. The worst was 2003 with 21; the latest was 2025.
See how the dates are worked out, and reading the West Nile counts.