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When does the rainy season start in South Florida? – NBC 6 South Florida


South Florida’s rainy season is officially here, but it’s starting in a rather unexpected way. Today’s prediction? Heat in the mid 90’s and barely a shower in sight, very different to what we are used to this time of year!

The season, which ends on October 15, runs parallel to the Atlantic hurricane season, which also has set start and end dates. But why should the rainy season start on a warm and dry day in mid-May?

In recent years, a series of criteria have been measured to determine the “official” start and end of the rainy season. This included observing consecutive days with high temperatures in the mid to upper 80s and dew point temperatures above 70°F. This combination creates the familiar ‘sticky’ feeling in the air.

Additionally, the metric of afternoon storms over land and nighttime storms over Atlantic waters helped mark the shift in the season. Due to the varying nature of these somewhat subjective parameters, the determination of the start of the season was made retroactively. That was of little use to the residents once the season had already started.

Since 2018, the National Weather Service in Miami has moved to a definitive start and end date for the rainy season, regardless of weather conditions.

This move, intended solely to indicate the expected summer pattern in the region, provided residents with a more consistent forecast. Just as you shouldn’t necessarily expect a tropical system to form on June 1, daily storms don’t automatically ignite on May 15.

It was the desire to distance ourselves from subjective parameters that led to a start and end date being appointed. This period, which generally mirrors the time when South Florida will see a wet weather pattern, allows residents to reasonably anticipate stormy days and unbearably balmy nights.

The rainy season in South Florida is responsible for 60-70% of the region’s annual rainfall. Packed into five months that don’t produce rain every day, that’s a significant amount of rain. Urban areas average 13 to 18 inches of rain during this time, but due to the nature of the scattered showers and storms, seasonal totals may vary from place to place.

What is consistent about South Florida’s rainy season is the somewhat predictable phases it exhibits. The first phase, which lasts from late May to early July, is often the stormiest and produces the greatest number of severe weather days. The highest frequency of storms occurs from Memorial Day through July 4.

In mid-summer, South Florida enters the hottest and driest phase of summer. There will be a slight decrease in overall shower activity as more stable easterly winds may limit showers into the night and early morning hours, creating hot and dry afternoons. Additionally, gusts of Saharan air may move through the region, suppressing tropical activity and daily storms.

The season’s homestretch takes place around Labor Day and continues through mid-October. This period brings the greatest variability of rainfall to the area. This is due to the possibility of passing tropical systems and the eventual approach or arrival of cold fronts. Of course, all these factors can influence the local rainfall pattern later than October 15th. In practice, it is usually a strong cold front that moves through the state, encapsulating the normal swings of South Florida’s rainy season.

While the 2024 rainy season won’t start with a bang, it’s inevitable that it will show its face soon enough, bringing days of rain to recharge pools, landscaping and waterways in the area.