Phoenix mosquitoes multiply wherever water sits, so activity jumps after rain and during monsoon season. Most bites are just itchy, but some people get large, hot, swollen reactions that point to a mosquito bite allergy. Here's what drives Phoenix mosquito season, how to cut down bites at home, and when a reaction is worth a closer look.
Why Phoenix mosquito season gets so bad
Mosquitoes need standing water to breed, and the Valley's heat speeds up their life cycle. Maricopa County Environmental Services notes that rain events and the start of monsoon are key times for mosquito activity (Maricopa County Mosquito Toolkit). Mild winters can also mean an early start to the season.
Common backyard breeding spots include:
- Plant saucers, buckets and bird baths
- Leaky irrigation, hoses and outdoor faucets
- Pools with poor circulation and swamp coolers that don't drain
- Tarps, pool covers and low spots in the yard after storms
How to cut down bites at home
Maricopa County recommends the "Four Rs" (Fight the Bite):
- Repel: use an EPA-registered repellent, such as one with DEET, picaridin or oil of lemon eucalyptus, and follow the label.
- Remove: tip out standing water every week, even small amounts.
- Repair: fix torn window and door screens.
- Remind: share these tips with family and neighbors.
Mosquitoes that carry West Nile virus are most active from dusk to dawn, so long sleeves and closed doors in the evening help too.
Normal bite vs. a bigger reaction
A typical bite is a small, itchy bump that fades within a few days.
A stronger reaction, sometimes called skeeter syndrome, can cause:
- Swelling much larger than the bite itself
- Redness, warmth or hardness around the bite
- Blistering or bruising
- Reactions that seem to get worse each season
Kids, new Arizona residents, and people who are outdoors often may notice bigger reactions. Learn more on our mosquito allergy page.
When to get help
Call 911 right away if someone has trouble breathing, swelling of the face, lips or throat, hives all over the body, dizziness or fainting after a bite.
Book a visit if:
- Your bites swell to several inches or keep getting worse
- Reactions are disrupting sleep, work or outdoor time
- You're not sure whether swelling is an allergy or an infection
- Your child reacts strongly every monsoon season
How Carefree Allergy and Asthma can help
We offer mosquito allergy testing as a $50 add-on to an allergy testing visit. If testing shows an allergy, treatment is with allergy drops you take at home, with no shots. You can visit us at our North Phoenix clinic, or by telehealth anywhere in Arizona.
Frequently asked questions
When is mosquito season in Phoenix?
Activity rises with heat and rain and often peaks during and after monsoon. It can start early in years with mild winters.
Why do mosquito bites swell so much on me?
Some people have a stronger immune reaction to proteins in mosquito saliva. Large, hot, swollen bites can be a sign of mosquito allergy.
Is skeeter syndrome dangerous?
It's usually uncomfortable rather than dangerous. Go to emergency care right away for any trouble breathing or throat swelling.
Can you test for a mosquito allergy?
Yes. We offer mosquito allergy testing as a $50 add-on to an allergy testing visit.
Do you treat mosquito allergy with shots?
No. We treat it with allergy drops you take at home.