Will pollen allergies get worse in South Florida as climate turns hotter?

Ashley Miznazi, Miami Herald on Apr 24, 2025

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It’s that time of the year when yellow pollen coats everything from windshields to streets. It’s not just from flowers and shrubs. Pollen that piles up under oak and pine trees also add some of the sneeziest allergens to the mix.

Some studies suggest that warmer temperatures — climate change is driving Miami’s temperatures up if you haven’t noticed — will encourage trees to produce more pollen earlier. But there are many factors that contribute to pollen production and temperature is just one of them. In subtropical South Florida, the days can get so hot that the rising mercury might actually discourage pollen production.

One study frequently pointed to draws on data collected over a 28-year period across the United States, including in Tallahassee and Tampa. It found that up until 2018 warming temperatures and increasing carbon dioxide in the atmosphere caused increased pollen concentrations, as well as earlier and longer pollen seasons.

But other factors complicate things down here in South Florida, said Marc Frank, a botanist at the University of Florida’s Herbarium in Gainesville.

“It just depends. Like, are we in a drought period? Was there a lot of cold before that warm? Or was it consistently warm? There’s a number of variables that figure into it,” Frank said.

In most of the country, there is little pollen to trigger allergies in the winter months because plants are not actively flowering and producing pollen. Then in the spring, trees pump out pollen which the wind spreads around, including into your nostrils. But in South Florida, when plants are always always in bloom, pollen production tends to be year round, Frank said.

A map from the U.S. National Phenology Network shows that in 2024 in the central U.S. spring arrived earlier, but in Florida the timing was different. Spring arrived late in the northern part of the peninsula and there wasn’t a significant change in the arrival of spring in the southern part of the peninsula.

Frank also expects that extreme high temperatures might actually reduce pollen in South Florida.

While warm temperatures will lead to increased pollen counts over a longer period in some areas of the country, there is some data indicating that extremely high temperatures above 90 to 95°F can actually have a negative impact on pollen production, Frank said.

“If South Florida experiences more days above 90°F, especially unseasonably hot days earlier in the year, it is possible that the total amount of pollen and the length of allergy season could decrease,” Frank said.