Yes, you can snorkel in Key West in December. The water at NOAA’s Key West harbour gauge averages 75.3 °F (24.1 °C) in December, and Fury Water Adventures says the reef water is usually in the mid to upper 70s. Average highs are about 77 °F and lows about 66 to 68 °F, and December is in the dry season. For a short stop a rash guard is usually enough; take a wetsuit if the boat has one and you feel the cold. Cold fronts bring windy days, so book early in your stay. Fury says it operates 365 days a year, but check the booking calendar for 25 December, 31 December and 1 January before you plan around them.
A trip that splits the time between the deck and the water suits December well. Fury’s Dolphin Watch and Snorkel Tour combines dolphin watching with one snorkel stop, leaves the booth at Greene and Elizabeth streets at 10:00 a.m. and 2:00 p.m., runs three hours and costs from $73 per person (checked November 2026), with 4.7 from 1,247 reviews on Viator. Our review covers what the dolphin part involves.
Key West Dolphin Watch and Snorkel Tour - Eco Adventure
- 4.7/5 (1,247 reviews)
- About 3 hours
- Free cancellation
- Operated by Fury Water Adventures
Includes Use of snorkeling equipment · Local guide · Unlimited soft drinks
You'll choose your date and complete the booking on Viator. Free cancellation under Viator's standard terms; the booking page shows the deadline.
December water and air temperature
December is the month the water settles into its winter range. NOAA’s long-term monthly mean for the Key West gauge is 75.3 °F, down from 78.3 °F in November and above January’s 72.5 °F. The afternoon air is only a degree or two warmer than the sea.
| November | December | January | |
|---|---|---|---|
| Water, monthly mean | 78.3 °F (25.7 °C) | 75.3 °F (24.1 °C) | 72.5 °F (22.5 °C) |
| Average high | 80.6 to 81.0 °F | 76.9 to 77.7 °F | 74.7 to 75.8 °F |
| Average low | 69.8 to 72.2 °F | 66.0 to 68.3 °F | 62.9 to 65.5 °F |
| Average rain | 3.28 in | 2.22 in | 2.01 in |
Air figures are National Weather Service 1991-2020 normals, shown as the range across the NWS’s two Key West tables; rain is from the NWS Key West table.
Two things pull the real water below the average. The gauge is in the harbour, and Fury says reef water in winter can dip into the mid-60s °F after a cold front. Single Decembers also run cool: in December 2024 the gauge averaged about 72.6 °F, closer to a typical January. Plan for mid 70s and pack for low 70s. Our water temperature by month page has the full year.
Cold fronts and wind in December
The National Park Service, describing the weather around the Dry Tortugas west of Key West, says winter cold fronts bring cooler, windier conditions and that winter seas are usually rougher than summer seas. December is when those fronts become part of the forecast.
A front can make the ride to the reef choppy, and on some days an operator decides not to go. Fury says its tours “will not depart in unsafe weather conditions” and that it will make “every effort” to reschedule you during your stay. Nobody publishes how often that happens, so:
- Book your snorkel trip for the first or second day of your stay, with a free day after it.
- Choose a listing with free cancellation; the reef trips on our best Key West snorkeling tours page show their policy on the listing.
- If you get seasick, take medication before you board, as the CDC advises, and sit away from the bow.
Our winter snorkeling guide covers fronts and wind across the whole season.
Other experiences
Other Key West snorkeling trips to compare
More ways to explore the area. Each listing shows its own cancellation policy.
Christmas Day, New Year’s Eve and New Year’s Day
Holiday sailings are not published in one place, so check each date on the trip you want.
- Christmas Day. Fury’s FAQ says “Fury operates 365 days a year” and links its special holiday trips, but it does not list a Christmas Day schedule. Sunset Watersports has a Christmas page without visible sailing times. Open the booking calendar on the trip you want and look at 25 December itself.
- New Year’s Eve. Fury and Sunset Watersports both promote New Year’s Eve trips on their own websites. Their sailing times were not published on the pages we read, so check the calendar.
- New Year’s Day. We found no operator statement about 1 January sailings. Check the calendar for that date too.
If your holiday date shows no departures, book the day before or after. December weather can move a trip anyway, so a holiday-week snorkel works best with a spare day behind it.
What to wear in December
December water sits between November’s swimsuit weather and January’s wetsuit weather.
- In the water: a rash guard at least. Fury aims its wetsuit offer at January and February visitors, but if you feel the cold, ask the operator if your December trip carries wetsuits. Danger Charters lists “comfortable wetsuits for the winter months” on its half-day kayak, snorkel and sail trip. A thin neoprene top from home also works.
- On the boat: a dry long-sleeve top or light jacket and a towel. With average lows of about 66 to 68 °F, the ride back on an afternoon trip can feel cool.
- For the sun: a hat and reef-safe sunscreen. Fury requires sunscreen without oxybenzone or octinoxate and hands out mineral sunscreen free on its snorkel trips; NOAA recommends a rash guard to cut the amount of sunscreen that goes into the water.
Which trips make sense in December
All the usual Key West trips run in December. These fit the month best.
- Dolphin-and-snorkel trips. They spend part of the trip looking for dolphins from the deck, so your time in cool water is one stop. Besides Fury’s trip above, Honest Eco’s dolphin watching and guided snorkel is run by a biologist-owned company, from $143 per person with 4.9 from 598 reviews on Viator. See our dolphin snorkel guide.
- Midday reef trips. An afternoon departure around 12:30 to 1:00 p.m. puts your swim in the middle of the day. Sunset Watersports’ Afternoon Reef Snorkeling with Open Bar leaves at 1:00 p.m. See our afternoon snorkeling guide.
- Mixed groups. If someone in your family does not want to get into 75 °F water, Fury’s glass-bottom boat lets them see the reef dry. Our family snorkeling guide covers trips for children.
The seasonal 2 Reef Snorkel Tour and Sunset Cruise from Sunset Watersports has no December dates; its Viator schedule starts on 7 March 2027.
To compare December with other months, see our guide to the best time to snorkel in Key West. If your trip runs on into the new year, read the January guide, which covers the coolest water of the year.
Frequently asked questions
Can you snorkel in Key West in December?
Yes. Snorkel boats run through December, and the harbour water averages 75.3 °F. Cold fronts bring some windy days, when an operator may move your trip, so book early in your stay.
Can you swim in Key West in December?
Yes. The water averages 75.3 °F (24.1 °C), cool on entry but fine for a swim. A swimsuit or rash guard is enough for a short swim; a wetsuit helps on a longer snorkel stop.
Is the water warm in Key West in December?
Mild. The harbour gauge averages 75.3 °F in December, and Fury says reef water is usually in the mid to upper 70s. After a strong cold front it can dip into the mid-60s.
Do snorkel boats run on Christmas Day in Key West?
Fury says it operates 365 days a year, but no operator we checked publishes a Christmas Day schedule. Open the booking calendar for the trip you want and check 25 December before you plan the day.
What is Key West weather like in December?
Dry and mild, with average highs of about 77 °F and lows of about 66 to 68 °F in the NWS 1991-2020 normals, and about 2.2 inches of rain for the month. Cold fronts bring cooler, windier spells.
Pick your morning or afternoon
Reef trips leave Key West most days of the year. Wind decides which reef the captain chooses, so check your date and book with free cancellation where you can.
Check dates and prices