Do Mosquitoes Really Disappear in Jacksonville Winters?

Jacksonville residents hope for relief from mosquitoes, but winters here are rarely cold enough to stop them totally.

Let’s just address the obvious upfront: Jacksonville winters are barely winters. At least not by the standards mosquitoes follow, anyway.

Your friends up north might be complaining about how cold it is. But they’re at least able to celebrate months of pest-free weather. Meanwhile, you could still be swatting at mosquitoes on warm February afternoons.

It's the price we pay for paradise. Even our "cold" months hover around 65°F during the day, which is basically mosquito paradise weather.

Jacksonville’s Winter Climate and Mosquito Activity

Up north, mosquitoes enter diapause during the winter. It’s the prolonged cold weather that does them in. But in Jacksonville, cold temperatures usually happen in brief snaps.

Mosquitoes become sluggish below 50°F and will enter diapause during sustained temperatures of 45°F. And it’s here that Jacksonville's winter averages tell the whole story: December and January highs reach around 66-67°F, with lows dipping to the mid-40s.

Freezing weather happens here—much to the chagrin of gardeners around here. But those brief cold snaps, bad as they are for squash plants, rarely last long enough to force mosquitoes into true dormancy. Most winter days warm up enough by afternoon to reactivate any mosquitoes that were lying low.

It’s also pretty sunny here too. Jacksonville averages 221 sunny days per year. Those sunny winter afternoons can push temperatures well above the mosquito activity threshold, especially in warmer microclimates around your home.

Where Do Mosquitoes Go in the Winter?

In truly cold climates, mosquito eggs, larvae, and adults have distinct winter survival strategies. Adults typically die off, larvae freeze in standing water, and only hardy eggs survive to restart populations come spring. But winter around here poses no real threat as far as mosquitoes are concerned.

Our abundant wetlands, rivers, retention ponds, and backyard water features all maintain relatively stable temperatures throughout winter months. Even when air temperatures drop, these water sources stay warm enough to support mosquito larvae development. Take for example the St. Johns River—mosquitoes can stay near the water which tends to retain heat and, from their perspective, barely ever see a temperature below 50.

Adult mosquitoes don't need to enter true diapause when they can simply wait out brief cold snaps in storm drains, under decks, or in thick vegetation. Because they never go into diapause, when the brief cold snaps end, they're ready to resume feeding and breeding activities.

You Will See Mosquitoes in Typical Jacksonville Winters

Even in December and January, daytime warmth can stir up mosquito activity around your home. Don't be surprised to see them buzzing around during those 70-degree winter afternoons that make Jacksonville winters the envy of Mainers. Warm spells lasting several days can trigger breeding cycles, meaning new generations emerge even during winter months.

And what makes it worse: many homeowners let their guard down during winter. It’s easy to assume mosquito control in Jacksonville FL isn't necessary during the winter. But as we’ve discussed here, mosquitoes remain active year-round.

And with year-round mosquitoes comes year-round disease risk. West Nile virus, Eastern Equine Encephalitis, and other mosquito-borne illnesses don't take winter breaks in Florida. Some species remain active throughout winter, particularly the Asian tiger mosquito and yellow fever mosquito that thrive in our climate.

This is where natural mosquito control is especially valuable during winter months. If you take control now when things are comparatively quiet, you’ll stop populations from exploding in the spring. Remember: even mosquitoes that appear after winter storms can establish breeding sites if left unchecked.

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Also read: How Long Do I Have to Stay Off My Yard After Mosquito Treatment?