Mosquito season in Clay County, NE: when it starts and ends

Mosquito months in Clay County

In a normal year mosquito season in Clay County, NE starts around April 13 and ends around October 23, about 27 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 Clay County, and when

• Start tipping out standing water weekly by March 30.
• Book any yard treatment for mid April, ahead of the July peak.
• Repellent can go away after October 23.
• 4 West Nile cases since 2016 (last 2025): you should use repellent at dusk June to August, more so if over 60.

Clay County against the rest of NE

Clay County has the 8th longest season of 93 NE counties, at 192 days against 200 in Richardson County and 127 in Sioux County. Its mean temperature is 51.6°F.

• Adams County: April 13 to October 22 (192 days, 17 WNV)
• Cass County: April 13 to October 22 (192 days, 12 WNV)
• Hall County: April 13 to October 22 (192 days, 37 WNV)
• Howard County: April 13 to October 22 (192 days, 8 WNV)

West Nile in Clay County

From 1999 to 2025, CDC ArboNET counted 59 human West Nile cases in Clay County (5 neuroinvasive) across 11 years. The worst was 2003 with 38; the latest was 2025.

More: how the dates are worked out · reading the West Nile counts.