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

Mosquito months in Custer County

In a normal year mosquito season in Custer County, NE starts around May 2 and ends around October 9, about 23 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 Custer County, and when

• Start tipping out standing water weekly by April 18.
• Book any yard treatment for early May, ahead of the July peak.
• Repellent can go away after October 9.
• 14 West Nile cases since 2016: you should wear EPA-registered repellent at dusk July to August, and check NE spray notices.

Custer County against the rest of NE

Custer County has the 87th longest season of 93 NE counties, at 160 days against 200 in Richardson County and 127 in Sioux County. Its mean temperature is 48.7°F.

• Thomas County: May 1 to October 10 (162 days, 2 WNV)
• Keya Paha County: May 1 to October 9 (161 days, 0 WNV)
• Garden County: May 2 to October 9 (160 days, 4 WNV)
• Dawes County: May 5 to October 7 (155 days, 5 WNV)

West Nile in Custer County

From 1999 to 2025, CDC ArboNET counted 101 human West Nile cases in Custer County (11 neuroinvasive) across 20 years. The worst was 2003 with 63; the latest was 2025.

See how the dates are worked out, and reading the West Nile counts.