Weather 101 - Sea and Lake Breezes Rule Florida's Weather

Florida experiences some very localized rainfall patterns mainly due to summertime sea breezes, the Lake Okeechobee lake breeze and Florida's every-present high humidity. These winds, driven primarily by land-water differences (and sometimes influenced by the overall wind flow pattern), lead to localized convergence zones (also referred to as "fronts") where thunderstorms are most likely to develop. The winds push cooler air from over water across heated land.

Although the storms can move and can redevelop, rainfall is often focused in specific areas.

On Florida's east coast, prevailing easterly trade winds push the sea breeze front far inland, leaving coastal areas mostly rain-free after an initial morning shower. When easterly winds decrease or are replaced by prevailing westerly winds, the sea breeze tends to hug the coast.

On the west coast, easterly or southerly winds tend to keep the sea breeze locked in nearer the coast, but with westerly winds, the sea breeze reaches further inland. Figure 1 shows a summertime sea breeze pattern across the Florida peninsula.

In the panhandle, sea breezes create even more interesting convergence zones due to the character of the coastline (bays and headlands areas). The area southeast of Tallahassee is a prime thunderstorm area, for example. And the region where the west coast bends westward is a thunderstorm minimum area (because of diverging sea breeze winds). This is shown in Figure 2 (statewide rainfall for just the 7-day period ending August 16th).

In Lake Okeechobee's case, the shear size of the lake creates local winds that blow from the lake to nearby land areas on most days. This leads to clear skies over the lake but a ring (complete or partial) of storms surrounding it. If the lake breeze interacts with the east coast sea breeze, storms can become quite intense.

This thunderstorm pattern has lead to a highly variable rainfall distribution in Collier County (southwest Florida south of Fort Myers). For the first seven and a half months (through and including August 15th), some nearby inland locations have logged between 20 and 30 inches of rainfall. Coastal locations (including downtown Naples) have had far less. My rainfall total (downtown Naples) is only approaching 12 inches (see Figure 3).

It's easy to see this variability when driving. On very stormy day recently, I went from "gully washer" mode 2 miles east of Interstate 75 on Immokalee Road in north Naples to dry roads about 1 mile west of I75 (Figure 4). I75 lies just east of the 21.24" and 22.11" rainfall reports but west of the 29.49" report in Figure 3.

And, a local landscaper I know has noticed it, too. He commented the other day about how dry it has been for his coastal clients while his lawn mowing is backed up inland.

But, when the sea breeze relaxes later in the day (as solar heating lessens), the sea breeze front often starts working itself back towards the coast. For this reason, coastal locales may be storm-free during the afternoon, but get a lightning show and heavy rain showers during the evening.

You can read the follow-on article about other weather patterns that lead to localized thunderstorm development. You'll discover that they do not occur as "randomly" as some would have us believe.