How cold does Orlando actually get — and is your heat big enough for it?

January is Orlando's coldest month, and a normal January night bottoms out around 50°F. The airport sees a night or two below freezing in an average year. Some winters have none. Others get a hard snap, like January 2018, when Orlando dropped to 27°F. That sounds mild, and mostly it is. It also explains why so many Central Florida heating systems go untested until the one night they matter.

Your neighborhood may be colder than the forecast

The temperature on the evening news is the airport reading, and the airport sits inside the metro's urban heat island. On a clear, calm winter night, open and rural ground loses heat faster, and cold air settles into low spots. Toward the edges of the metro, lows several degrees below the downtown reading are common, along with frost on the grass when downtown has none. That includes north toward Sanford, northwest through Apopka toward Zellwood, and the open country east of St. Cloud.

A heating system that is marginal at 38°F in College Park can be short of heat at 33°F in a Rock Springs Ridge cul-de-sac on the same night.

What that asks of a heat pump

Load calculations for Orlando use a winter design temperature around 40°F. That is the temperature a system should handle comfortably on its own, not the record low. Heat pumps here are sized for the summer cooling load, which is much larger than the winter heating load. At 47°F a heat pump puts out roughly as much heat as its rated cooling capacity. As it gets colder it loses some output, but it still has plenty for a Florida house.

In practice, a working heat pump in a typical Orlando home carries the house alone into the mid-30s. It needs the strips only for defrost and the coldest few hours of the year. If yours leans on the strips at 50°F, it is not undersized. It is faulty. See aux heat vs emergency heat.

What it asks of heat strips

On a straight-cool system, the heat kit is the only heat you have, so its size matters more. A rough guide, not a load calculation:

The maximum kit is set by the air handler model and by what the electrical panel can carry. Our heat kit cost guide covers sizes, circuits and prices.

Undersized or failing? How to tell

Undersized heat runs without stopping on the coldest night of the year and lets the house slide a degree or two below the setpoint. It recovers by mid-morning and is fine on an ordinary 45-degree night.

Failing heat cannot hold the setpoint on a 50-degree night, or the Aux light stays on for hours. A common version: a 10 kW kit is really two 5 kW elements. When one element or its sequencer dies, half the heat is gone, and the system still feels warm on a mild day, so nobody notices until it is cold. The only way to catch it is to measure the current draw on each stage, which is part of every heat check we do.

What we see in particular neighborhoods

• Sanford's historic district: older homes with plaster walls, older windows and little or no attic space to insulate lose heat faster than the square footage suggests. They often need the larger kit, or attention to air sealing first.
• Apopka: a lot of manufactured housing, which heats with an electric furnace or a package unit rather than a standard air handler. That is a different set of parts and faults, covered in mobile home heat not working.
• St. Cloud and Harmony: many builder-grade systems are coming off warranty at around ten years. Some were installed with the smallest kit the handler allows, or none at all.

Our $89 pre-winter heat check measures every strip stage and checks the heat pump's defrost and reversing valve, so you know what you have before the first cold front tests it. Details are on our heating repair page.