Mosquito season in Passaic County, NJ: when it starts and ends
Mosquito months in Passaic County
In a normal year mosquito season in Passaic County, NJ starts around April 17 and ends around October 26, about 27 weeks.
- Jan
- Feb
- Mar
- Apr
- May
- Jun
- Jul
- Aug
- Sep
- Oct
- Nov
- Dec
What to do in Passaic County, and when
- Start tipping out standing water weekly by April 3.
- Book any yard treatment for mid April, ahead of the July peak.
- Repellent can go away after October 26.
- 7 West Nile cases since 2016 (last 2025): you should use repellent at dusk July to August, more so if over 60.
Passaic County against the rest of NJ
Passaic County has the 18th longest season of 21 NJ counties, at 192 days against 217 in Cape May County and 184 in Sussex County. Its mean temperature is 51.7°F.
- Burlington County: April 15 to October 27 (195 days, 20 WNV)
- Somerset County: April 15 to October 26 (194 days, 9 WNV)
- Morris County: April 18 to October 22 (188 days, 8 WNV)
- Warren County: April 18 to October 21 (186 days, 7 WNV)
West Nile in Passaic County
From 1999 to 2025, CDC ArboNET counted 17 human West Nile cases in Passaic County (13 neuroinvasive) across 10 years. The worst was 2012 with 4; the latest was 2025.
Background: reading the West Nile counts; how the dates are worked out.