MIAMI (CBSMiami) — The only way to know that we are almost a week into rainy season is the fact that there is a specific start and end date.  May 15 marks the start of the season, but since then only 0.01 inches of rain has been recorded in Miami with Fort Lauderdale picking up 0.08 inches. Both remain a few inches below normal for the year compared to the average.

It was 2018 when the National Weather Service picked an average start date declaring the start and end of the rainy season, May 15-October 15. Prior to that, the National Weather Service in Miami would specify the start and end date of the season, but it was subjective and often announced days later. An attempt to use a more scientific method to determine the start and end of the season such as dewpoint thresholds and instability but that led to more problems.

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“They used to start rainy season once the dew points remained above 70.  But that was problematic because sometimes even with a 70-degree dew point, it doesn’t rain,” explained CBS4 Chief Meteorologist Craig Setzer.

Other factors like the amount of instability in the atmosphere was not consistent between storms over the Everglades and the Metro areas of Miami-Dade and Broward Counties. The delay between the start of the season and the official announcement was also problematic with this method.

“It led to many different folks announcing when they thought it began. That’s why they just made it a fixed date for the start and end,” said Setzer.


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Close to 60 inches of rainfall occurs in the Miami area every year. 70% of that comes during the rainy season. This puts an end to the wildfire season which runs right up to a little beyond the start of the rainy season.

“The wildfire risk also increases as you approach the start of rainy season.  So, until we get into a rainy season pattern, the risk for substantial wildfires grows every day,” said Setzer. With abundant tropical moisture trapped to the south and the strong breeze, the Wildfire risk will remain high through the weekend.


May 15th is a day that, on average, the rainy season pattern develops. Now with the set date, forecasters can officially say that the rainy season is underway, but just like hurricane season, the atmosphere doesn’t have to go along just because it’s marked on a calendar.

Hurricanes can develop outside of hurricane season just like the current dry weather pattern is occurring in the “rainy” season.

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“The winds have been over the waters this past week and now the ocean temps have cooled down. That will likely delay a true rainy season pattern,” according to Setzer.

Dave Warren