Key Biscayne faces a second straight week of heavy rain and possible street flooding. The National Weather Service forecasts 2 to 6 inches of rainfall through Monday, Sept. 28.
The worst-case scenario is worse. Weather service meteorologist Sammy Hadi said there is a 1-in-10 chance South Florida could receive 6 to 15 inches over that stretch.
"Most likely rainfall amounts of 2-6 inches are forecast over the next seven days with a reasonable worst case … scenario of receiving 6 to 15 inches of rainfall," Hadi said, as first reported by the Miami Herald on Monday, Sept. 21.
A low-pressure system sitting in the upper atmosphere is pumping tropical moisture into the region, according to CBS News Miami meteorologist Lissette Gonzalez. She called the atmosphere "juicy" and said the pattern would keep conditions soggy through Sunday, Sept. 27.
Daily storms expected on Key Biscayne through Thursday
The weather service's point forecast for Key Biscayne calls for storms each day through Thursday, Sept. 24, with highs in the upper 80s:
- Tuesday, Sept. 22: Showers and thunderstorms likely after 2 p.m. High near 87. Chance of rain: 70%.
- Wednesday, Sept. 23: Showers and thunderstorms, mainly before 5 p.m., continuing into the evening. High near 86. Chance of rain: 80%.
- Thursday, Sept. 24: Showers likely after 2 p.m. High near 87.
Across the broader Miami area, the weather service pegged Wednesday's storm chance at 88%, with a 90% chance of rain between 2 and 7 p.m. The agency flagged a marginal risk of excessive rainfall each afternoon through Wednesday.
Island's low-lying streets already flood several times a year
Key Biscayne sits in Miami-Dade County's evacuation Zone A, the most flood-vulnerable designation, according to the Village of Key Biscayne's flood preparedness page.
The island's lowest-lying streets already flood about 15 times a year, the Miami Herald reported in January 2025. Without infrastructure fixes, some spots could see up to 90 days of flooding annually by 2040. The village's first road-raising project carries an estimated price tag of more than $88 million to elevate 2 miles of streets.
Islander News reported that Key Biscayne received more than an inch of rain on Monday, Sept. 21, with some storms producing locally heavy rainfall.
Tropical Storm Fay poses no threat to South Florida
Tropical Storm Fay, which had maximum sustained winds near 65 mph as of Monday, Sept. 21, is not headed toward South Florida. National Hurricane Center forecaster John Cangialosi said the storm was expected to weaken and possibly become a post-tropical cyclone within a day or two. Gonzalez confirmed Fay poses no threat to the area.
The weather service forecast runs through Monday, Sept. 28, with rain chances staying at 60% to 70% each afternoon through Sunday, Sept. 27.
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