Honestly, if you're looking at a standard Florida forecast and thinking "warm and sunny," you're probably going to get caught off guard by Key Biscayne. This island doesn't play by the same rules as mainland Miami. While the city swelters, the Key breathes. But today, Friday, January 16, 2026, the story is actually about a crisp, cool shift that has the locals reaching for their "Florida winter" sweaters.
We’re talking about a significant dip. Right now, in the early hours of this Friday, it’s a cool 50°F. It actually feels like 45°F because of a steady 15 mph wind coming in from the northwest. If you’re heading out for an early morning walk at Bill Baggs, you’re going to feel that bite.
The Reality of Key Biscayne Weather Hourly Transitions
Most people assume the tropical vibe stays locked in 24/7. Not today. This morning is clear and quiet, but as we move through the daylight hours, the temperature is going to struggle to climb. We are looking at a projected high of 69°F, which is actually quite refreshing if you’re planning on hitting the tennis courts or biking the Crandon Park trails.
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By the time the sun is up, the conditions will shift to partly sunny. That northwest wind that was chilling the early birds will settle into a more northern flow at about 14 mph. It’s the kind of day where the shade feels cold but the sun feels amazing.
What to Expect Hour by Hour
Basically, the day is split in two. The morning is for the "cold" weather enthusiasts, and the afternoon is for the sun-seekers.
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- 7:00 AM: Expect it to stay around its lowest point, roughly 47°F. Clear skies, but definitely chilly.
- Noon: The sun starts doing its job. We should see temperatures hitting the low 60s. The humidity is sitting low at 54%, so it won't feel sticky at all.
- 4:00 PM: This is your peak window. It’ll hit that 69°F mark. The UV index is a 4, which is moderate—you can still get a burn if you’re out there all afternoon, so don't let the cool air fool you.
- Tonight: As we roll into the evening, the clouds start moving in. It’ll become mostly cloudy, and there’s a small 15% chance of rain after dark. The temperature won't drop as drastically as it did last night, likely hovering around 47°F again toward the very end of the cycle.
Why the Island Microclimate Matters
Kinda crazy how a bridge can change the weather, right? The Rickenbacker Causeway acts as a gateway to a slightly different atmosphere. Because Key Biscayne is surrounded by water, it usually stays a few degrees warmer than the mainland during a cold snap, but the wind exposure is much higher.
If you're out on a boat near the Yacht Club today, that 14 mph wind from the north is going to create a light chop on the bay. It's manageable, but it’s not the glass-smooth water you see in the summer.
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Dealing with the "Cool" Key
Let’s be real: 69 degrees is "winter" for us. While tourists from New York might be in the ocean (the sea temperature usually stays around 74°F in January), the locals are staying on the sand. The chance of rain during the day is almost non-existent—only 5%—so your outdoor plans are safe. Just bring a windbreaker.
Actionable Next Steps for Today:
Pack layers. If you’re starting your day before 10:00 AM, you need a heavy hoodie or a light jacket. By 2:00 PM, you’ll want to be in a t-shirt to soak up that partly sunny warmth. If you’re planning a sunset dinner at the Rusty Pelican or any of the spots on the water, the transition back to mostly cloudy and 47°F will happen faster than you think, so keep that jacket nearby.