Mosquito season in New Madrid County, MO: when it starts and ends

Mosquito months in New Madrid County

In a normal year mosquito season in New Madrid County, MO starts around March 19 and ends around November 10, about 34 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 New Madrid County, and when

• Start tipping out standing water weekly by March 5.
• Book any yard treatment for mid March, ahead of the July peak.
• Repellent can go away after November 10.
• 1 West Nile case since 2016 (last 2025): you should use repellent at dusk June to September, more so if over 60.

New Madrid County against the rest of MO

New Madrid County has the 3rd longest season of 115 MO counties, at 236 days against 242 in Pemiscot County and 187 in Crawford County. Its mean temperature is 59°F.

• Pemiscot County: March 16 to November 13 (242 days, 0 WNV)
• Dunklin County: March 19 to November 13 (239 days, 0 WNV)
• Butler County: March 20 to November 9 (234 days, 3 WNV)
• Scott County: March 21 to November 8 (232 days, 0 WNV)

West Nile in New Madrid County

From 1999 to 2025, CDC ArboNET counted 2 human West Nile cases in New Madrid County (1 neuroinvasive) across 2 years. The worst was 2025 with 1; the latest was 2025.

See how the dates are worked out, and when mosquitoes go away for the winter.