Dry Tortugas in July: Weather, Sea Temperature, Rain Days and Daylight

DRY TORTUGAS · JULY · KEY WEST NORMALS · 1991–2020

July puts Dry Tortugas at full summer strength. The Gulf around Fort Jefferson is close to bath temperature, the days run past thirteen and a half hours, and the evenings stay warm enough to eat dinner in a T-shirt at the campground. It is also a hurricane-season month, and everything about the trip, from the boat seat to the Key West room, should be booked with that in mind.

You have already picked the island. What follows the decision is timing: how hot July runs, how often it rains, how warm the water is, and whether June or August would serve you better. Every crossing starts in Key West, seventy miles east, so flights into Key West and a night in town come first.

On this page

• Dry Tortugas weather in July90.2°F highs, 80.6°F lows and 6.8 rain days
• Water temperature at Dry Tortugas in July88.7°F at the surface, as a daily-maximum mean
• Crowds and prices in JulySummer vacation, booking and the lodging tax
• Things to do at Dry Tortugas in JulyWhere 88.7°F water and 13 h 33 min of light take you
• Two-day Dry Tortugas plan for JulyFrom a 6:46 am sunrise to an 8:19 pm sunset
• July vs June and AugustHow the three months compare on heat, rain and sea
• Is July a good time to go?Who should go in July and who should wait

The island itself, the fort’s history and the boat and seaplane options sit in our Florida national parks guide, with fees and passes. The year-round picture is in the best time to visit Florida.

Dry Tortugas weather in July: average highs, lows and rain days

NOAA’s National Centers for Environmental Information publish the 1991–2020 normals for the Key West station, USW00012836: an average July high of 90.2°F, an average low of 80.6°F and 3.63 inches of rain. It is an official station with a real thermometer, a sturdier basis than a gridded reanalysis. It also stands seventy miles east of Fort Jefferson. Dry Tortugas sits alone in open Gulf, windier and with nothing between it and the weather, so read every figure here as Key West’s July and expect the islands to feel more exposed.

Measurable rain, a tenth of an inch or more, falls on 6.8 days of an average July in Key West. That is about one day in five, so a two-day trip has a fair chance of meeting a shower and a good chance of missing one. A tenth of an inch can be a single passing cell. Florida’s wet season runs on afternoon thunderstorms, and the practical move is to plan the open-water hours for the morning.

Only 9.6°F separates the average high from the average low. Nights never cool the way a desert or mountain night does, so there is nothing warm to pack. Bring a light long-sleeve layer for sun on the boat deck, a hat, and more drinking water than feels necessary. Campers can leave the sleeping bag at home and pack a sheet. The full list of what to carry and what the park allows is in what to know before you go to Florida.

On July 15 the sun rises at 6:46 am and sets at 8:19 pm Eastern Daylight Time, for about 13 hours 33 minutes of daylight. The low sun of early evening is the kindest light on the fort’s brick, and campers get the whole of it after the day visitors have left the dock.

Can you swim in Dry Tortugas in July? Sea temperature

Yes. Open-Meteo’s Marine API puts the sea surface off Dry Tortugas at 88.7°F in July, averaged over 2015–2024. The figure is a mean of daily maxima, the warmest reading of each day, so it runs a shade warmer than a 24-hour average would. It comes from a different source and a different decade than the Key West air normals, and the two sets compare loosely.

In the water, 88.7°F sits 1.5°F below the average July high and 8.1°F above the average low. A swimmer walking in at midday feels almost no step down from the air, and at dawn the sea is warmer than the beach. Nobody needs a wetsuit for warmth in July. A long snorkel will not cool you down much, so drink before you go in and again when you come out.

We found no verified wind or swell figures for Dry Tortugas in July, so we give no wave height and no wind speed. The setting is known: the islands lie exposed in open Gulf, windier than Key West, and July falls inside the Atlantic hurricane season, June 1 to November 30. Check the marine forecast and the tropics the day before your crossing.

How busy is Dry Tortugas in July? Crowds and prices

July falls in the middle of the summer school vacation, a calendar fact rather than a price ranking. We found no occupancy or fare series for Dry Tortugas or Key West, so we crown no month cheap or expensive. At state level, the Florida calendar puts the annual price peaks at holiday weeks and spring break, with early December and May as the quiet stretches.

The seats that decide the trip are on the boat or seaplane out of Key West. We could not verify their capacity or how far ahead they sell out in July, so we give no number of weeks. Book the crossing as soon as your dates are fixed, then the Key West bed. Fares, the park entrance fee and passes are in our national parks guide, and budget tiers in what a Florida trip costs.

We could not verify the Monroe County lodging-tax rate, so we give no percentage for your Key West nights. Ask for the total with taxes and any resort fee before you pay, and compare neighborhoods in our Key West guide.

Paying more for flexibility changes a July trip more than paying for comfort. A refundable room and a changeable crossing cost more up front. They also let you slide the island day when a tropical system or a rough marine forecast turns up, and in hurricane season that option is the most useful thing money buys.

Things to do in Dry Tortugas in July

July puts the warmest water of early summer under your mask: 88.7°F at the surface, 2.1°F above June’s 86.6°F. Add 13 hours 33 minutes of daylight on the 15th, and a day visit has room for a long swim session, while an overnight stay turns into two full days in the water.

The visit centers on Fort Jefferson, the brick fort that covers most of Garden Key, with its moat and the moat wall that snorkelers trace from the shore. Garden Key’s beaches are the swim and snorkel entry points, and Loggerhead Key and its lighthouse lie farther west for those with their own boat. We could not verify hours or access rules for any of them, and the only figure our sources give for these waters is the 88.7°F sea surface. The park’s current rules are in our national parks guide.

The water barely moves from July to August, 88.7°F to 88.8°F, so the season shows up in the air. With an average afternoon high of 90.2°F, the fort’s parade ground and ramparts are best walked early, and the midday hours go to the water. By late afternoon the sun is lower, and a second fort walk before the 8:19 pm sunset suits campers.

We could not verify the entrance fee or any fee-free days in July, so we list nothing as free beyond the view itself. Campers on Garden Key get sunrise at 6:46 am and sunset at 8:19 pm over open water at no extra charge.

Dry Tortugas in July: a two-day itinerary

Day one, the island. Be at the Key West departure early, around the 6:46 am sunrise, while the air is at its coolest. Confirm your departure time when you book. Once on Garden Key, walk Fort Jefferson first, before the day climbs toward its 90.2°F average high. From late morning into early afternoon, swim and snorkel off the beaches and along the moat wall, with shade breaks and water on hand. Campers keep the evening, a second walk on the ramparts and light until 8:19 pm.

Day two, the backup. Day-trippers spend it in Key West, with a morning outside, the hottest hours under cover and an evening on foot, all in our Key West guide. Campers wake at 6:46 am on the island, swim before breakfast and ride back later. If the weather turns, and Key West averages 6.8 days of measurable rain in July, swap the two days so the crossing lands on the calmer one. That swap is why the refundable fare matters.

Dry Tortugas in July vs June and August

Air figures come from the same NOAA Key West normals for all three months, and sea figures from the Open-Meteo Marine API. July runs 1.5°F hotter than June by day and only 0.4°F cooler than August. It carries the smallest rain total of the three, 3.63 inches against 4.23 in June and 5.37 in August, though June has slightly fewer rain days, 6.4 to July’s 6.8. August jumps to 9.1. In the water, July sits 2.1°F above June and 0.1°F below August.

Moving four weeks earlier into June buys you a day high of 88.7°F and a night low of 79.4°F, at the cost of 2.1°F of sea warmth and 0.6 inch more rain. Moving four weeks later into August gains a tenth of a degree in the water. In exchange you get 2.3 more rain days, 1.74 more inches of rain and a date closer to the hurricane season’s September peak.

Is July a good time to visit Dry Tortugas?

Yes, for swimmers, snorkelers and campers who handle heat well and can keep their dates loose. July is harder for anyone who wants cool air for a long walk around the fort, for travelers who cannot move a date, and for families whose school calendar pins them to one fixed week in hurricane season.

If the heat is the problem, June is the nearest fix, 1.5°F cooler by day with water still at 86.6°F. If you want dry, settled air, look at the November-to-April dry season, laid out in the best time to visit Florida, and accept cooler water in return.

Of the three summer months, only July pairs the lowest rain total at the Key West station, 3.63 inches, with sea water within a tenth of a degree of August’s 88.8°F.

The last word

Choose July for the water, then protect the date: a refundable Key West room, a changeable crossing and a look at the tropics the night before you sail. The heavy-rain risk is small at the Key West station, where an inch or more falls on just 0.8 day of an average July. Pack the mask and fins, board early, and be in the water off Garden Key before the day reaches its 90.2°F high.

Sources & data for this guide

• July, June and August air normals (highs, lows, precipitation, days at 0.10 in or more, days at 1 in or more) · NOAA NCEI monthly normals 1991–2020, Key West station USW00012836, seventy miles east of Dry Tortugas · checked Sep 24, 2026
• Sea surface temperature, July, June and August · Open-Meteo Marine API, mean of daily maxima, 2015–2024 · checked Sep 24, 2026
• Daylight, sunrise and sunset on July 15 · sunrise-sunset.org, converted from UTC to Eastern Daylight Time · checked Sep 24, 2026
• Hurricane season dates and Florida seasonal price peaks · from our Florida orientation, sourced to NOAA NHC and editorial observation
• We could not verify wind or swell data, ferry and seaplane schedules, fares, the park entrance fee or the Monroe County lodging-tax rate. Check operators and the National Park Service when you book.

To plan your stay

• Best Time to Visit Dry Tortugas: Weather, Sea Temperature and the Quiet Months
• Dry Tortugas in June: Weather, Sea Temperature, Rain Days and Crowds vs May and July
• Dry Tortugas in August: Weather, Sea Temperature, Rain Days and Hurricane Season
• Dry Tortugas in May: Weather, Sea Temperature, Crowds and a Two-Day Plan

Nearby places

• Key West Travel Guide: Driving Down US-1, Old Town Parking Rates, Fort Zachary Taylor and the Cruise Ship Vote
• Everglades National Park: The Complete Visitor's Guide
• Big Cypress National Preserve: Dark Sky Park, Swamp Buggies and the $100 ORV Permit