Mosquito season in Shelby County, TN: when it starts and ends

Mosquito months in Shelby County

In a normal year mosquito season in Shelby County, TN starts around March 15 and ends around November 17, about 35 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 Shelby County, and when

• Start tipping out standing water weekly by March 1.
• Book any yard treatment for mid March, ahead of the July peak.
• Repellent can go away after November 17.
• 47 West Nile cases since 2016: you should wear EPA-registered repellent at dusk May to September, and check TN spray notices.

Shelby County against the rest of TN

Shelby County has the 3rd longest season of 95 TN counties, at 247 days against 252 in Hamilton County and 186 in Carter County. Its mean temperature is 62°F.

• Hamilton County: March 11 to November 18 (252 days, 6 WNV)
• Sequatchie County: March 12 to November 15 (248 days, 0 WNV)
• Haywood County: March 16 to November 17 (246 days, 0 WNV)
• Lauderdale County: March 14 to November 14 (245 days, 0 WNV)

West Nile in Shelby County

From 1999 to 2025, CDC ArboNET counted 205 human West Nile cases in Shelby County (154 neuroinvasive) across 23 years. The worst was 2002 with 40; the latest was 2025.

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