Biscayne National Park in December: Weather, Sea Temperature and Crowds

FLORIDA · BISCAYNE NATIONAL PARK · DECEMBER

December lands Biscayne National Park in Florida’s dry season, with the sea still a touch warmer than the afternoon air. That pairing sets up the whole trip: a boat out to the keys, a swim in bay water close to 79°F, and a sunset early enough that you plan dinner around it.

The park is almost all water, so your December question is about one day on a boat and where you sleep on either side of it. Most visitors fly into Miami (our Florida flights guide compares the airports), base in the city or near Homestead, and pair the park with the Everglades next door. Two or three nights cover both.

On this page

• Biscayne weather in DecemberHighs of 78.2°F, lows of 64.3°F, 3.7 rain days
• Can you swim in December?Sea at 79.1°F, measured as daily maxima
• Crowds, booking and lodging taxHoliday weeks against early December
• Things to do in DecemberConvoy Point, Boca Chita Key, Elliott Key, Stiltsville
• A two-day December itinerarySunrise at 6:58 a.m., back ashore by 5:33 p.m.
• December vs November and JanuarySea at 81.7°F, 79.1°F and 77.0°F
• Is December a good time to visit?Who should go now, and who should pick November

Deciding between neighboring months? The same numbers for Biscayne in November and Biscayne in January sit one click away, and the statewide calendar lives in our Florida best-time guide.

Biscayne National Park weather in December: average highs, lows and rain days

The air figures are official NOAA NCEI normals for 1991-2020, read from a real thermometer at the Miami station (USW00012839), immediately north of the park. That station sits in a city, and Biscayne is almost all open water. Water swings less than pavement in both directions, so every figure here describes Miami, and the bay itself likely runs a little milder at both ends of the day. On those normals, a December afternoon averages 78.2°F and a December night 64.3°F.

Rain is light by Florida standards. An average December collects 2.44 inches, and only 3.7 days reach a tenth of an inch. Spread across 31 days, that puts measurable rain on roughly one day in eight, so a three-night stay usually runs dry. Keep one flexible day in the plan anyway, since a single wet morning can cancel a boat departure.

From the 64.3°F low to the 78.2°F high is a spread of 13.9°F, and the boat makes the morning end of it feel colder. Pack a light long-sleeved layer or windbreaker for the crossing, a swimsuit and reef-safe sunscreen for the afternoon, and a dry towel for the ride home.

On December 15 the sun rises at 6:58 a.m. and sets at 5:33 p.m. Eastern Standard Time (converted from 11:58 and 22:33 UTC), for 10 hours and 35 minutes of daylight. A boat trip that leaves mid-morning has about seven usable hours before the light fades, and the return leg belongs inside them.

Can you swim in Biscayne National Park in December? Sea temperature and what it feels like

The sea surface off the park averages 79.1°F in December, according to the Open-Meteo Marine API over 2015-2024. That figure is the mean of each day’s maximum, typically reached in the afternoon, so it reads a shade warmer than a 24-hour average would. Expect the water to feel slightly cooler at 9 a.m. than at 3 p.m.

Yes, you can swim. At its daily peak the water sits 0.9°F above the 78.2°F average high on land, so an afternoon dip feels mild the moment you are in. The chill comes on getting out into a breeze, which is why the towel and the layer matter more than a wetsuit for most swimmers and snorkelers.

We could not read wind or wave data for December, so we give no figure for chop on the bay or swell on the ocean side. Before you book a boat, check the National Weather Service marine forecast for Biscayne Bay, and ask the operator what conditions cancel a departure.

How busy is Biscayne National Park in December? Crowds and prices

December opens the dry season, the stretch that built Florida’s winter travel industry. Our Florida overview puts the holiday weeks among the state’s annual peaks and early December among its quieter stretches. We found no visitor count or room-rate series for the park itself, so we rank no December week against another beyond that calendar signal.

We found no booking-lead data either, so we name no number of weeks. The calendar still gives the order of operations: a stay that touches Christmas or New Year gets booked before one in the first half of the month, and the boat seat before the bed. Our Florida where-to-stay guide covers the Miami bases.

We could not verify the lodging-tax rate for a Miami-Dade stay, so we give no percentage. Check the total with taxes and any resort fee at checkout, and see our Florida trip-cost guide for how those extras add up.

The boat is the one line where spending more changes the month. Without one, a Biscayne visit stays on the mainland shore at Convoy Point. With one, December’s warm water and dry air open the keys. We could not verify current tour fares or rental rates, so budget for the boat before the hotel upgrade.

Things to do in Biscayne National Park in December

December lets you pair a dry-season boat day with a swim that still feels warm. By January the sea’s daily peak drops to 77.0°F, and November carries 1.09 more inches of rain. For snorkeling and island time in one outing, December holds both halves.

The mainland base is the Dante Fascell Visitor Center at Convoy Point, near Homestead, where the park’s boat departures start. Offshore, Boca Chita Key has its small harbor and ornamental lighthouse, Elliott Key is the largest of the park’s islands, and Stiltsville is the cluster of houses built on pilings in the bay. Divers and snorkelers follow the Maritime Heritage Trail across historic wrecks. We could not verify December hours or tour schedules for any of them, so confirm with the park before the drive.

The water lags behind the air as winter sets in. From November to December the average high falls 3.1°F while the sea’s daily peak falls 2.6°F, and the dawn gap widens: December’s 64.3°F low sits 14.8°F under the sea’s maximum. That gap shapes the day. Cool on the morning crossing, comfortable in the water by early afternoon.

We could not verify entrance, dock or tour fees for December, so we quote none. Park fees and the annual pass sit in our Florida national parks guide, alongside the other parks you might add to the same trip.

Biscayne National Park in December: a two-day itinerary

Day one, the boat. Reach Convoy Point soon after the 6:58 a.m. sunrise, with the layer on and the swim gear packed. Board a mid-morning departure so the crossing comes as the air warms, and save the snorkel or swim for early afternoon, when the sea nears its daily maximum. Aim to be back at the dock by 4:30 p.m., an hour before the 5:33 p.m. sunset, and plan dinner on the mainland.

Day two, the backup. Keep this day open for a second boat outing, or drive west into the Everglades for the boardwalks. If the marine forecast turns or rain arrives on one of December’s 3.7 wet days, move the boat to day two and do the Everglades first. Our getting-around guide covers renting a car in South Florida.

Biscayne National Park in December vs November and January

On NOAA’s Miami normals, December runs 3.1°F cooler by day and 4.0°F cooler by night than November, and 2.0°F warmer by day and 3.3°F warmer by night than January. Rain falls from 3.53 inches in November to 2.44 in December and 1.83 in January, though January’s 3.8 wet days nearly match December’s 3.7. The sea, from Open-Meteo’s marine data, steps down from 81.7°F to 79.1°F to 77.0°F.

Moving four weeks earlier gains 2.6°F of sea and milder nights, at the cost of 1.09 more inches of rain, one more wet day on average and the last month of hurricane season, which runs through November 30. Moving four weeks later trims 0.61 inch of rain, but the sea loses 2.1°F and dawn drops to 61.0°F, colder for the boat ride out.

Is December a good time to visit Biscayne National Park?

Yes, if your trip is built around one boat day and a swim: December combines dry-season air with water that still reaches 79.1°F at its peak. It suits families on a winter break and anyone pairing the park with Miami. It suits less well the swimmer who wants bathwater, or the traveler whose dates fall on the holiday weeks and who dislikes a busy season.

For warmer water, pick November, with the sea at 81.7°F and nights at 68.3°F, and book refundable because of the hurricane season. For the driest air and a quieter post-holiday stretch, January works if a 77.0°F sea feels warm enough.

Of the three months, December is the one where the sea’s daily peak sits furthest above the average afternoon high, 0.9°F against 0.4°F in November and 0.8°F in January.

The last word

Book the boat before the bed, and put it on the first clear morning of your stay. December’s odds are on your side: on the Miami normals, an inch-plus downpour shows up about one December in two, averaging half a day per month. Be at Convoy Point after sunrise with a towel and a warm layer, and you’ll have the bay, the keys and the afternoon swim before the light goes at 5:33.

Sources & data for this guide

• December, November and January air normals, precipitation and rain days · NOAA NCEI monthly normals 1991-2020, Miami station USW00012839 · checked Sep 24, 2026
• Station scope: measured at Miami, north of a park that is almost all water · NOAA NCEI · checked Sep 24, 2026
• Sea surface temperature, mean of daily maxima, 2015-2024 · Open-Meteo Marine API · checked Sep 24, 2026
• Daylight, sunrise and sunset on December 15 · sunrise-sunset.org, converted from UTC to EST · checked Sep 24, 2026
• Holiday-week and early-December calendar signal · The Travel Chronicle Florida overview
• We could not verify boat-tour schedules and fares, entrance or dock fees, visitor-center hours, lodging tax, booking lead times or December wind and wave data. We found no event dated for December. Check the park and operators when you book.

To plan your stay

• Best Time to Visit Biscayne National Park: Month-by-Month Weather, Sea Temperature and the Month to Skip
• Biscayne National Park in January: Weather, Sea Temperature, Crowds and a Two-Day Plan
• Biscayne National Park in November: Weather, Sea Temperature, Crowds and a Two-Day Plan
• Biscayne National Park in February: Weather, Sea Temperature, Crowds and a Two-Day Itinerary

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• Big Cypress National Preserve: Dark Sky Park, Swamp Buggies and the $100 ORV Permit
• Miami Travel Guide: Miami or Miami Beach, Neighborhoods, Beaches and Getting Around Without a Car
• Fort Lauderdale Travel Guide: State Park Beaches, FLL and the 12% Hotel Tax