Key West in May: Weather, Sea Temperature, Crowds and Prices

KEY WEST · MAY · 24.55° N

May hands Key West a sea at 84.6°F and a calendar with no hurricane season in it. Afternoons average 85.9°F, nights hold at 76.4°F, and rain shows up on about four days of the month instead of settling in. The water’s daily peak sits well above the temperature the air falls to before dawn, so the ladder at the end of a dock stops being a decision and becomes a formality.

What the month takes back is April’s dryness. Rainfall climbs from 2.07 inches to 3.12, wet days from 2.8 to 4.1, and both keep rising into June. Anything not fixed to the date belongs elsewhere: our Key West guide covers the island itself, the statewide calendar covers the other eleven months.

On this page

• Key West weather in MayHighs of 85.9°F and 4.1 wet days
• Sea temperature in May84.6°F, measured as daily maxima
• Lodging tax and parking rates11% on a room, $48 a day in the garage
• Things to do in Key West in MayFort Zachary Taylor, the Hemingway house, Dry Tortugas
• A two-day plan for Key WestDay one on foot, day two on the 8 a.m. ferry
• May, April or June?April at 79.8°F water, June at 6.4 wet days
• Is May a good time to visit?Yes for swimmers, and the case for April

Key West sits at the end of US-1, roughly 155 miles and close to four hours from Miami without stops, six to eight with them. None of that changes in May, and our Keys road trip guide has the mile markers and the toll warning. What changes in May is what waits at the end of the drive, and the figures below start with the thermometer at the airport.

Key West weather in May: average highs, lows and rain days

These numbers come from a thermometer rather than a model: NOAA’s 1991-2020 monthly normals for station USW00012836, at Key West International Airport. May’s average high is 85.9°F, the average low 76.4°F. A station record and a grid-cell reanalysis are not the same product, and the gap between them is measurable, because gridded data smooths a two-by-four-mile island into the sea around it. Every figure here is a thirty-year average, so a given May can run warmer, wetter or both.

Rain totals 3.12 inches, delivered in a handful of visits rather than a season. In an average May, 4.1 days record at least 0.10 inch, roughly one day in seven, and only 0.9 day reaches a full inch. Six days in seven do not even reach a tenth. Book the 8 a.m. boat and the beach afternoon as though they will happen, because the standard shape is a shower that darkens the harbor for twenty minutes and moves west.

Nights barely cool: 76.4°F on average, 9.5°F below the day’s high. Nothing in that spread argues for a sweater, so the packing decision moves to sun, salt and air conditioning. A brimmed hat and reef-safe sunscreen outwork any jacket, one light long-sleeve shirt covers both the early boat and a restaurant running its AC hard, and shoes matter because Old Town is the largest wooden historic district in North America and is built to be crossed flat, on foot or by bicycle.

On May 15 the sun rises at 6:41 a.m. and sets at 8:05 p.m. Eastern, 13 hours and 23 minutes of daylight. That late sunset rearranges the evening. Fort Zachary Taylor stays open until sundown, and the Sunset Celebration at Mallory Square begins about two hours before the sun goes, so performers are setting up around six in full daylight. The beach hour worth protecting runs from five to seven.

Can you swim in Key West in May? Sea temperature and what it feels like

Sea surface off Key West averages 84.6°F in May across the Open-Meteo Marine record for 2015 to 2024. One nuance travels with that figure: it is the mean of daily maxima, the warmest reading of each day, so it sits a shade above a true 24-hour mean. Tables that publish a full-day average will show a slightly cooler number for the same water, and both readings are correct.

At 84.6°F there is no entry shock, no wetsuit question and no ten-minute acclimatization at the ladder. That is nearly 5°F above April’s 79.8°F, the single largest difference between the two months for anyone planning a day around a mask and fins. The constraint becomes sun rather than cold: a rash guard, reapplied sunscreen and the boat’s shade between drifts do more for a long snorkel than any amount of tolerance for cool water.

We found no monthly wind or wave series for Key West, so we give no average for either. The calendar does say something useful: the Atlantic hurricane season runs June 1 to November 30 and peaks on September 10, and May falls outside it entirely. The 70-mile crossing to Dry Tortugas still answers to the day’s conditions, and the ferry cancels for weather when it must, so put that trip early in the stay rather than on the final morning.

How busy is Key West in May? Crowds, prices and the demand peak

We can only half answer where May sits in the price year. We found no occupancy series and no monthly room-rate series for Key West, so we crown no month cheap or expensive. Two things are calendar rather than opinion: May is the last full month before hurricane season opens on June 1, and it comes after March, the statewide spring-break peak we describe in the Florida calendar.

Book the boat before the bed. The Yankee Freedom III, the ferry to Dry Tortugas, sails daily at 8 a.m. with check-in closing at 7:30, and it sells out weeks ahead, so a month of lead time is the floor rather than the safe margin. For rooms we could not verify a booking-window series, so we give no number of weeks. The ferry is the reservation that can delete an entire day of a short trip if it is left late.

The tax on a room is knowable to the decimal. Monroe County levies a 5.0% transient rental tax, filed and paid alongside the 6% state sales tax, so a quoted nightly rate arrives at the desk carrying 11% on top. May is taxed exactly as January is. Resort fees and property parking charges sit outside that 11%, set by the hotel rather than the county, and they are the line that varies between two addresses on the same street.

Street meters run $3.00 an hour, the Old Town Parking Garage $6 an hour or $48 a day plus tax, the Mallory Square lot $7 an hour or $48 a day with a ten-hour cap, and the Key West Bight lot $5 an hour or $40 a day. In a month averaging 85.9°F, the upgrade that repays itself is a bed within walking distance of Duval, with the car parked once for the stay. City parking rates change, so check before you count on them.

Things to do in Key West in May

The water has reached 84.6°F and the Atlantic hurricane season still does not open until June 1. April cannot offer the first, June will not promise the second. For anything that involves leaving a dock, that pairing decides more than the air temperature does. The run west to Dry Tortugas, the reef, the sandbars off the flats: in May they are warm-water outings without the storm-watching habit that starts on the first of June.

Fort Zachary Taylor Historic State Park holds the beach most often called the island’s best, within walking distance of Old Town. Entry is $2.50 on foot or by bicycle, $4.50 for a single-occupant vehicle or motorcycle, and $6.00 per car for up to eight people plus a $0.50 county surcharge per person. The park runs 8 a.m. to sundown, 365 days, with the fort itself closing at 5 p.m. The Ernest Hemingway Home and Museum takes walk-ins 9 a.m. to 5 p.m. daily, $19 adult, $7 child, free under 6.

Those fees and hours do not move with the calendar, but the air around them does. Fort Zachary’s beach in April sits on 79.8°F water under an 82.6°F sky. In May it is 84.6°F water under 85.9°F air, and that is the difference between a quick swim and an afternoon. The Hemingway house works the opposite way. Its shaded veranda and 9 a.m. opening are worth more in May than in winter, because a sensible May day goes outside early, indoors at midday, outside again at five.

The Duval Loop bus costs nothing and calls at 18 stops through Old Town, though its timetable is the one figure our sources disagree on. One gives every 20 minutes from 8 a.m. to 10 p.m., another every 30 minutes from 6 to 10 a.m. and every 15 minutes until midnight, so read the stop sign rather than a printout, and note it does not serve the airport. The Sunset Celebration at Mallory Square is free too, every night of the year, weather permitting, filling the pier by about six for an 8:05 sunset in mid-May.

Key West in May: a two-day itinerary

Day one runs on foot. Sunrise at 6:41 a.m. buys a cool hour in Old Town, and Mile Marker 0 at Whitehead and Fleming, the southern end of a route running about 2,370 miles north to Fort Kent, Maine, is photographable before anyone queues for it. Take the Hemingway house at its 9 a.m. opening, eat lunch indoors, and give the hot stretch to key lime pie, official pie of the State of Florida since 2006. At four, walk to Fort Zachary Taylor, pay the $2.50 and swim. Mallory Square from six, sunset at 8:05.

Day two belongs to the 8 a.m. ferry. Check-in for the Yankee Freedom III closes at 7:30, the 2026 adult fare runs about $250 with park entry, snorkeling gear, breakfast and lunch included, and the boat covers 70 miles west to a national park no road or bridge reaches. If the sky turns, keep 4.1 wet days in proportion: showers, not washouts. Trade the boat day for the drive back up the Overseas Highway and the old Seven Mile Bridge, where a restored two-mile span carries walkers and cyclists from a car park at the Marathon end, with Pigeon Key halfway out.

Key West in May vs April and June

Set the three months together and May reads as the hinge. Air climbs 3.3°F from April to May, then another 2.8°F into June. Rain follows the same slope: 2.07 inches, then 3.12, then 4.23, with wet days going 2.8, 4.1, 6.4. The sea makes the biggest single jump of the sequence, 79.8°F in April to 84.6°F in May, and then gains only 2.0°F more by June.

Shifting four weeks earlier buys a drier month and costs almost 5°F of water: April’s 2.8 wet days against May’s 4.1, with a sea at 79.8°F that still wants a rash guard on a breezy boat. Shifting four weeks later costs the calendar, since June 1 opens hurricane season, and adds 2.3 wet days plus 88.7°F afternoons. Swimmers should take May over April. Anyone whose plan is walking Old Town from nine to five may prefer April’s 82.6°F.

Is May a good time to visit Key West?

Yes for swimmers, snorkelers and anyone booking the Dry Tortugas boat. May delivers 84.6°F water, 13 hours 23 minutes of daylight in mid-month, and a hurricane season that has not started. Rain on 4.1 days does not threaten a week. No for travelers who want long midday walking, or who find 85.9°F with a 76.4°F night uncomfortable, and no for anyone who needs the driest spring week the island offers.

If that last description fits, April is the month to move to. It keeps walking weather at 82.6°F, cuts rainfall to 2.07 inches and wet days to 2.8, and it also sits outside hurricane season. The cost is the water at 79.8°F, swimmable without being luxurious, and our April page carries the rest of that argument.

May pairs 84.6°F water with a calendar that has no hurricane season in it, and neither neighboring month manages both.

The last word

Decide the boat first and let the rest of May arrange itself around it, because showers arriving on 4.1 days are hours, not lost days. One piece we have kept back: the cruise limits Key West voters approved in November 2020, a cap of 1,500 disembarking passengers a day and a ban on ships carrying more than 1,300 people, were nullified by SB 1194, the state law barring local ballot measures from restricting maritime commerce, written to apply retroactively. The vote stands nullified and the big ships still call at the pier.

Sources & data for this guide

• May normals: highs, lows, rainfall and wet days · NOAA NCEI monthly normals 1991-2020, station USW00012836, Key West International Airport · checked Sep 23, 2026
• April and June normals, same series and same period · NOAA NCEI 1991-2020 · checked Sep 23, 2026
• Sea surface 84.6°F, mean of daily maxima 2015-2024 · Open-Meteo Marine API · checked Sep 23, 2026
• Daylight, sunrise and sunset on May 15, converted to Eastern time · sunrise-sunset.org · checked Sep 23, 2026
• Hurricane season dates and the September 10 peak · NOAA National Hurricane Center · checked Sep 23, 2026
• Transient rental tax of 5.0% filed with the 6% state sales tax · Florida Department of Revenue, form DR-15TDT · checked Sep 23, 2026
• Fort Zachary Taylor fees and hours · Florida State Parks · checked Sep 23, 2026
• Hemingway Home hours and admission · hemingwayhome.com · checked Sep 23, 2026
• Dry Tortugas access, ferry times and 2026 adult fare · National Park Service and Yankee Freedom / drytortugas.com · checked Sep 23, 2026 · fare subject to change
• Parking rates, meters, garage and lots · City of Key West Parking Department · checked Sep 23, 2026 · rates change
• Duval Loop stops, hours and frequency · City of Key West and local guides · checked Sep 23, 2026 · sources disagree on frequency and hours, so we give the range and send you to the stop sign
• Mile Marker 0 and the distance to Fort Kent, Maine · Atlas Obscura and Key West Travel Guide · checked Sep 23, 2026 · sources give 2,369 or 2,390 miles, so we give the order of magnitude
• Cruise referendum of November 2020 and SB 1194 preemption · Seatrade Cruise and Florida Politics · checked Sep 23, 2026
• We found no occupancy series and no monthly room-rate series for Key West, so we rank no month on price.

To plan your stay

• Things to Do in Key West: Hours, Prices, Hemingway House and the Dry Tortugas Ferry
• Where to Stay in Key West: Old Town, New Town and What Parking Costs
• Key West Airport to Old Town: Transfers, Parking and the Drive from Miami
• What to Know Before You Go to Key West: Parking, the Free Duval Loop, Sunset and the Dry Tortugas Ferry

Nearby places

• Everglades National Park: The Complete Visitor's Guide
• Big Cypress National Preserve: Dark Sky Park, Swamp Buggies and the $100 ORV Permit
• Dry Tortugas National Park: Ferry, the $15 Entrance Fee and Camping on Garden Key