Mosquito season in Barnwell County, SC: when it starts and ends

Mosquito months in Barnwell County

In a normal year mosquito season in Barnwell County, SC starts around March 5 and ends around November 30, about 39 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 Barnwell County, and when

• Start tipping out standing water weekly by February 19.
• Book any yard treatment for early March, ahead of the July peak.
• Repellent can go away after November 30.
• 2 West Nile cases since 2016 (last 2018): you should use repellent at dusk May to September, more so if over 60.

Barnwell County against the rest of SC

Barnwell County has the 14th longest season of 46 SC counties, at 270 days against 349 in Charleston County and 209 in Cherokee County. Its mean temperature is 64.1°F.

• Colleton County: March 1 to November 28 (272 days, 0 WNV)
• Aiken County: March 4 to November 30 (271 days, 5 WNV)
• Greenville County: March 3 to November 27 (269 days, 10 WNV)
• Bamberg County: March 3 to November 26 (268 days, 0 WNV)

West Nile in Barnwell County

From 1999 to 2025, CDC ArboNET counted 2 human West Nile cases in Barnwell County (2 neuroinvasive) across 2 years. The worst was 2018 with 1; the latest was 2018.

Background: when the season starts across the US; how the dates are worked out.