With local news reports of mosquitoes testing positive for West Nile virus in Franklin and Cumberland counties, many homeowners are asking the same question: When does mosquito season finally end?
While cooler temperatures in late summer and early fall may make it feel like mosquito season is winding down, mosquitoes can remain active much longer than many people realize. In south-central Pennsylvania, mosquito activity typically continues until temperatures consistently drop below 50 degrees. Warm fall weather can extend mosquito activity well into September and even early October.
With outdoor activities like National Hunting and Fishing Day on September 27th right around the corner, it is important to continue taking precautions. Whether you are spending time in the woods, around the water, or simply enjoying your backyard, protecting yourself from mosquito bites helps you stay comfortable and safe outdoors.
Understanding how weather affects mosquito activity can help you better protect your family, your pets, and your outdoor living spaces throughout the entire season.
What Is West Nile Virus and Should You Be Concerned?
West Nile virus is the most common mosquito-borne illness in the United States. It is transmitted to people through the bite of an infected mosquito. The virus is not spread through casual contact from person to person.
The good news is that most people infected with West Nile virus do not develop symptoms. For those who do, symptoms may include:
- Fever
- Headache
- Body aches
- Joint pain
- Nausea
- Skin rash
While many cases are mild, West Nile virus can cause more serious illness in some individuals, particularly older adults and people with weakened immune systems.
According to the Pennsylvania Department of Environmental Protection, mosquito surveillance has identified positive West Nile virus samples in our area. As of July 2026, one mosquito has tested positive in Franklin County and seven mosquitoes have tested positive in Cumberland County.
How Can You Reduce Your Risk?
If you spend time outdoors during mosquito season, there is always a chance of being bitten by a mosquito carrying disease. The best way to reduce your risk is to limit mosquito populations around your property and protect yourself when outdoors.
Homeowners can help reduce mosquito activity by:
- Eliminating standing water where mosquitoes breed
- Cleaning gutters and removing debris that can collect water
- Maintaining areas around the home where mosquitoes may hide
- Using EPA-approved insect repellents
- Considering professional mosquito control treatments
Now that I have answered when mosquito season ends, let’s talk about when it begins.
Many homeowners do not start noticing mosquitoes until after Memorial Day, but mosquito activity often begins much earlier. At Guardian Mosquito – Tick & Turf Control, we typically begin treatments once nighttime temperatures consistently stay above 50 degrees. This often occurs in early May, but during mild winters, mosquito activity can begin as early as late April.
Starting treatments early helps reduce mosquito populations before they become a major problem and helps provide protection throughout the peak summer months.
At Guardian Mosquito – Tick & Turf Control, we monitor weather patterns, adjust our approach throughout the season, and handle the treatment process from start to finish. Giving you the peace of mind to spend more time outside and enjoy your yard.
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