Mosquito season in Sierra County, NM: when it starts and ends
Mosquito months in Sierra County
In a normal year mosquito season in Sierra County, NM starts around March 1 and ends around November 20, about 38 weeks.
- Jan
- Feb
- Mar
- Apr
- May
- Jun
- Jul
- Aug
- Sep
- Oct
- Nov
- Dec
What to do in Sierra County, and when
- Start tipping out standing water weekly by February 15.
- Book any yard treatment for early March, ahead of the July peak.
- Repellent can go away after November 20.
- No West Nile cases since 2016, so bites in Sierra County are a nuisance; check window screens.
Sierra County against the rest of NM
Sierra County has the 2nd longest season of 33 NM counties, at 264 days against 268 in Doña Ana County and 114 in Catron County. Its mean temperature is 62.9°F.
- Doña Ana County: February 26 to November 21 (268 days, 26 WNV)
- Eddy County: March 5 to November 18 (258 days, 5 WNV)
- Lea County: March 10 to November 23 (258 days, 6 WNV)
West Nile in Sierra County
From 1999 to 2025, CDC ArboNET counted 2 human West Nile cases in Sierra County (2 neuroinvasive) across 1 year. The worst was 2007 with 2; the latest was 2007.
More: how the dates are worked out · when the season starts across the US.