Why Orlando Homes Get Moldy: Dew Point and Rain Data

Why Orlando homes get moldy

Orlando International averaged 137 days a year with a mean dew point of 70°F or more over 2016-2024, up from 118 over 1974-1990. That number, more than any leak, is why mold is a year-round business here.

Updated October 29, 2026 · Sources listed at the end

The dew point, not the temperature

Relative humidity changes all day with the temperature. Dew point doesn't: it's the temperature at which the air's water condenses, so it measures how much water is actually in the air. When the outdoor dew point is 74°F, any surface indoors cooler than 74°F can collect water: a supply vent blowing 55°F air, a closet wall shaded by a bed, the back of a dresser against an outside wall, the drywall above an air handler. Mold needs that water and not much else.

Days with a dew point of 70°F or more, by month

NOAA NCEI Global Summary of the Day, Orlando International Airport, 2016-2024 average. Outdoor air this wet is what an air conditioner has to pull water out of all day.

From June through September, the airport logs a 70°F dew point on about 113 of 122 days. July averages 30.9 such days and August 31, nearly every day. Even January averages a 50.9°F dew point, so a house closed up through a mild winter isn't safe either.

Longer runs, more years

The longest unbroken run of 70°F dew point days averaged 95 days each year over 2016-2024. In 2024 it lasted 127 days. That's more than four months in which the AC never gets a break from dehumidifying.

Days with a dew point of 70°F or more, per year since 1974

Our count from NOAA NCEI daily mean dew point at Orlando International Airport (72205012815). The highest year was 2018, with 159.

The AC is the dehumidifier

A Florida house without a basement or a furnace has one machine pulling water out of the air: the air conditioner. It only does that while it runs. Three habits defeat it:

An oversized system. It cools the house quickly and shuts off before it has removed much water, so the house is cold and clammy.
A high setpoint or off while away. At 82°F or with the system off for a two-week trip, indoor humidity climbs past 60 percent.
Leaky ducts in a hot attic. Supply air leaks out, hot humid attic air gets pulled in through the returns.

The EPA's guidance is to keep indoor relative humidity below 60 percent, ideally 30 to 50. How to keep an Orlando house dry.

Then the rain

The airport averages 50.9 inches of rain a year (2016-2025), and 59% of it falls from June through September in afternoon storms. There are about 14.5 days a year with an inch or more and 3.3 with two inches or more. A roof with one lifted shingle leaks a little every afternoon for a month. Roof leaks and ceiling mold.

Average rain by month, Orlando International Airport (inches)

NOAA daily data via ACIS, 2016-2025 average. June through September brings 59% of the year's rain.

And the storms

Hurricane Ian put 7.72 inches on the airport on September 28, 2022, the wettest day since records began in 1952, and 13.11 inches over two days. Rivers and creeks overflowed into neighborhoods far from any coast. See flood claims by ZIP.

Questions Orlando homeowners ask

Why does my house smell musty in summer?

Usually high indoor humidity. With outdoor dew points above 70°F most summer days, an AC that short-cycles, is set high or is off lets humidity build until mold grows on cool surfaces and in closets. Check indoor humidity with a cheap hygrometer; above 60 percent is the warning sign.

Is mold worse in Florida than other states?

The conditions for it are more constant. Orlando averages 137 days a year with a 70°F dew point, so houses depend on air conditioning to stay dry for much of the year. Where the AC falls behind, mold follows.

Does Orlando's humidity cause mold in new houses?

Yes. Newer houses are tighter, which keeps humid air in when the AC is oversized or set high. A clogged condensate drain or a shower pan leak in a new house grows mold as fast as in an old one.