September is a lovely time to visit the Florida Keys. The summer crowds have faded because the kids are back in school, and areas like Marathon settle into a slower, more relaxed rhythm as fall arrives.
And yet the best of summer remains. The Gulf waters are still warm, the sun continues to shine, and long days make it easy to explore.
Settling into a private, luxury vacation rental in the Middle Keys means you can enjoy the quiet season on your own schedule, complete with a pool and all the amenities your heart desires between your island adventures.
So before you get to planning your September trip, here is what to expect when visiting the Florida Keys.
Florida Keys Weather in September
Photo Credit: Kosoff
September in the Florida Keys brings warm tropical weather, brief afternoon rain showers, and some of the year’s best conditions for getting out on the water. Daytime highs hover around 88°F in the Middle Keys, with warm, humid evenings that stay near 79°F.
September is also the rainiest month of the year in the Keys, with about 6 inches of rainfall spread throughout the month. The good news? Most showers arrive as quick, heavy bursts rather than gloomy all-day rain, and are easy to predict, with most rain coming in the afternoon.
The real showstopper of September, though, is the water. Ocean temperatures are at their warmest, creating bath-like conditions that are perfect for snorkeling, taking long swims, paddleboarding and kayaking through mangroves, or simply floating in the crystal-clear turquoise waters without ever feeling a chill.
With summer crowds fading and winter visitors still months away, September offers a quieter side of the Florida Keys, where beaches, sandbars, and snorkeling spots feel refreshingly uncrowded.
Our Florida Keys weather guide and our Florida Keys in August guide compare the seasons side by side to help you find the best fit for your travel style.
Hurricane Season in September
Keep in mind that September falls within the middle of hurricane season, so the forecast can sometimes be a little unpredictable. That said, it does not mean a storm is guaranteed.
Most Septembers pass with nothing more than a few blustery afternoons, but it’s worth buying travel insurance and keeping an eye on the National Hurricane Center in the weeks before your trip.
Is September a Good Time to Visit the Florida Keys?
Yes. With the perfect mix of lovely weather, low crowds, and lots of outdoor activities, September is one of the best times to visit the Florida Keys.
The water is warm and inviting, the fishing is excellent, wildlife encounters are common, and there’s more room to enjoy the laid-back island lifestyle that makes the Keys so special. If you’re looking for fewer crowds, better value, and a chance to experience Marathon the way locals do, September might be exactly the time to go.
Our guide to the best time to visit Marathon breaks down how September compares with the rest of the year.
Middle Keys Events in September
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September brings a couple of events to the Florida Keys calendar, alongside the usual quiet-season pace.
Womenfest Key West 2026
- Date & Time: September 2 – 6, 2026
- Website: gaykeywestfl.com/womenfest
Womenfest Key West 2026 is an annual festival celebrating women through a week of entertainment, sporting events, live music, comedy, workshops, and social gatherings.
Drawing visitors from around the world, the festival promotes community, inclusivity, women’s empowerment, and the welcoming spirit for which Key West is known.
Marathon International Bonefish Tournament
- Date: Late September (TBC for 2026)
- Website: facebook.com/p/Marathon-Intl-Bonefish-Marathon-Tarpon-Tournaments
The Marathon International Bonefish Tournament is an annual tradition that brings anglers from around the world to the Florida Keys in pursuit of one of the region’s most prized game fish: the elusive bonefish.
Recognized as the oldest catch-and-release flats fishing competition in the Florida Keys, the tournament has celebrated the skill, patience, and excitement of bonefishing for more than five decades.
Often known as the “ghosts of the flats,” bonefish challenge anglers with their speed, stealth, and ability to disappear across the shallow waters of the Keys.
Things to Do in the Middle Keys in September
Photo Credit: Brocreative
While all of the Keys are lovely this time of year, the Middle Keys are particularly pleasant. Marathon doesn’t slow down when the crowds thin out; it simply gets easier to enjoy. Here’s how to spend your late-summer days soaking up the best of the Florida Keys.
Snorkel Sombrero Reef
Slip beneath the surface at Sombrero Reef and discover one of the Florida Keys’ most spectacular underwater worlds. Just a few miles offshore from Marathon, this vibrant coral reef is teeming with colorful tropical fish, graceful sea turtles, rays, and an incredible variety of marine life.
September is one of the best times to visit, with warm, clear water and fewer boats. Our full guide to Sombrero Reef Lighthouse covers what to expect on the swim out.
Visit the Turtle Hospital
The Turtle Hospital in Marathon offers a fascinating behind-the-scenes look at the rescue and rehabilitation of endangered sea turtles.
Guided tours introduce visitors to the hospital’s recovering patients, each with its own remarkable story of survival, while explaining the care and conservation efforts that help return many turtles to the wild. Our guide to visiting the Turtle Hospital has more on what the tour covers.
It’s a perfect September stop, especially when a passing afternoon shower interrupts beach plans, combining unforgettable wildlife encounters with a chance to support local conservation.
Paddle Curry Hammock State Park
Curry Hammock State Park‘s mangrove channels stay calm even when the open water gets choppy, which makes it a reliable pick in September.
Wildlife lovers will rejoice at the opportunity for up-close encounters with endemic and even endangered species. Paddle out early to spot herons, rays, and the occasional manatee before the afternoon heat sets in.
Our visitor’s guide to Curry Hammock State Park has rental and trail details.
Rent a Boat, Jet Ski, or Book a Sandbar Trip
September’s warm Gulf waters make it one of the best times to get out and experience Marathon from the sea. The real magic is found beyond the shoreline, where hidden coves, untouched stretches of sand, crystal-clear flats, and breathtaking coastal views are waiting to be discovered.
Whether you want a center console boat for the day, a jet ski rental, or a guided sandbar excursion, one thing is for sure: the scenery around Marathon is best enjoyed from the water.
Book a Sunset Cruise or Fishing Charter
Speaking of getting out on the water, cruising and fishing are two of the best Florida Keys activities.
Nothing quite like ending a day of exploring on a picturesque sunset cruise out of Marathon. Especially once the heat breaks in the evening, and the sky ignites in a fiery display of colors.
If you’d rather spend the day on the water casting your own line, September is a superb month for backcountry and offshore fishing charters chasing tarpon, mahi, and snapper. September means fewer boats on the water and more room to roam.
Joining a trip or booking a private charter gives anglers the chance to make the most of their Keys getaway and experience some of the best fishing of the season.
Take a Day Trip to Explore Other Florida Keys
One of the best parts about staying in Marathon is having the entire Florida Keys chain within reach. September is an ideal time to pack the car and hit the road for a day trip. With fewer cars on the Overseas Highway and fewer crowds at popular attractions, it’s easier to island-hop at your own pace.
You can wander through the colorful streets and attractions of Key West, discover Islamorada’s fishing culture, snorkel new reefs, visit local shops, or find a quiet waterfront spot that feels like your own private slice of paradise.
Be sure to check out our complete guide highlighting the very best day trips along the Florida Keys so you don’t miss out on hidden gems.
Packing for a September Trip to the Florida Keys
A few extra items in your luggage make a September trip in the Middle Keys noticeably better.
- Light layers: Humidity levels are high in September, so light, breathable clothing is best for combating the tropical summer heat.
- Mosquito repellent: You should also be prepared for insects, as mosquitoes and no-see-ums can be more noticeable in September, especially around dawn and dusk and in mangrove areas.
- Rain gear: Choose a compact rain jacket or poncho you can stash in a bag rather than a full umbrella. Afternoon showers can be frequent, so don’t get caught out in the rain.
Plan Your September Getaway in the Middle Keys
September is a fantastic time to experience the Florida Keys thanks to its warm waters, modest crowds, and unmistakable laidback island vibe that makes you want to stay a little longer.
With a private vacation rental in Marathon, Duck Key, or Key Colony as your home base, you’ll have the perfect place to unwind, recharge, and enjoy the relaxed side of the Florida Keys in September. Browse our Florida Keys vacation rentals to find your dream spot for the season.
