The short answer: December to April for the weather, May to September for the water. Key West has no bad month, but every month trades something, and a few specific dates in 2026 and 2027 decide more than the climate does. Here are the numbers, then the dates.
The year in one table
Air and rain are the National Weather Service’s 1991–2020 normals for Key West. Water and wind are averaged from NOAA’s Key West harbor station for 2021 to 2025; for most months its water readings begin in 2023. Sunset is the U.S. Naval Observatory’s time on the 15th, local time.
| Month | High / low °F | Rain, in | Water °F | Wind, mph | Sunset |
|---|---|---|---|---|---|
| Jan | 76 / 66 | 1.8 | 72 | 8.9 | 6:00 |
| Feb | 77 / 67 | 1.5 | 75 | 9.0 | 6:22 |
| Mar | 80 / 69 | 1.5 | 78 | 9.5 | 7:36 |
| Apr | 83 / 73 | 2.1 | 80 | 9.4 | 7:49 |
| May | 86 / 76 | 3.1 | 85 | 7.7 | 8:04 |
| Jun | 89 / 79 | 4.2 | 87 | 7.6 | 8:17 |
| Jul | 90 / 81 | 3.6 | 89 | 6.8 | 8:18 |
| Aug | 91 / 81 | 5.4 | 89 | 6.8 | 8:01 |
| Sep | 89 / 79 | 7.2 | 88 | 6.7 | 7:31 |
| Oct | 86 / 77 | 5.7 | 83 | 8.2 | 7:00 |
| Nov | 81 / 72 | 2.1 | 78 | 8.8 | 5:40 |
| Dec | 78 / 68 | 2.2 | 74 | 8.9 | 5:41 |
Read across and the trade is plain. Winter and early spring are dry and mild but windier, with the water in the 70s. Summer is hot and wet, with the calmest wind and the warmest water, which is what snorkelers and flats anglers want. September is the wettest month, and March, not January, is the windiest.
The state’s own prices say the same thing about demand: a cabin at Bahia Honda State Park is $160 a night from 1 November to 30 April and $120 from 1 May to 31 October.
The dates that decide a week, 2026–27
| When | What | Why it matters |
|---|---|---|
| 15 Oct 2026 – 30 Apr 2027 | Honest Eco’s dolphin sunset sail | The only months it sails; none from May to mid-October |
| 16–25 Oct 2026 | Fantasy Fest | It “takes over the streets of Old Town”; 22–31 Oct in 2027 |
| 22–23 Oct 2026 | No Dry Tortugas ferry | It sails on all the other days from 14 to 31 Oct, but 14–17, 26 and 28 Oct were sold out on 13 Oct; the ferry page has the other dark days |
| 31 Oct 2026 | Last Saturday in October | The Conch Tour Train’s one closure day, as the operator words it |
| 24 Nov, 11 Dec 2026; 19 Jan, 16 Feb, 17 Mar, 23 Apr 2027 | Ferry maintenance days | No Dry Tortugas ferry those days |
| 5, 12 and 31 Dec 2026 | Holiday parade, Lighted Boat Parade, New Year’s Eve | The Christmas and New Year’s page has the times, and the three midnight drops |
| 7–10 Jan, 26–31 Jan 2027 | Literary Seminar; Mile 0 Fest and the Food & Wine Festival | The January-to-March page has every festival date, the ships and the spring breaks |
| 1–26 Mar 2027 | Spring breaks | Eight of the ten school calendars on that page fall between 6 and 21 March |
| 16–25 Apr 2027 | Conch Republic Independence Celebration | Ten days marking the Keys’ secession of 23 April 1982 |
| 1 Apr – 31 Jul | Western Dry Rocks closed to fishing | A spawning closure about 10 miles southwest |
| 1 Jun – 30 Nov | Hurricane season | The evacuation record and rules |
| Late July | Hemingway Days | 21–26 July in 2026 |
| 28–29 Jul 2027 | Lobster sport season | Six per person in Monroe County; no night diving |
| 6 Aug – 31 Mar | Regular lobster season | Never in Dry Tortugas National Park or the sanctuary’s no-take zones |
| Early Jul – 30 Sep | Key West Garden Club | Closed Wednesdays and Thursdays |
Month by month
December to February. The dry season and the island’s high season. Average highs of 76 to 78°F, under two inches of rain a month, and the earliest sunsets of the year, around 5:40 p.m. in December, which puts Mallory Square before dinner. The water is at its coolest, 72 to 75°F, and a winter evening on a boat is cooler than it feels ashore. It is the season for the dolphin sunset sail, and Fishmonster’s offshore captains put sailfish at their best from December through April. Winter birds arrive in numbers from November, the refuge says. December’s parades, the Harbor Walk of Lights and the New Year’s Eve drops are on the Christmas and New Year’s page; January’s Literary Seminar, half marathon and food and music festivals, and February’s seafood and art festivals, are on the January-to-March page.
March and April. The windiest months, with little rain and the water warming from the high 70s to 80. The refuge calls it peak northbound bird migration, and sea turtle nesting begins in April. Western Dry Rocks closes to fishing on 1 April. Spring breaks run from 1 to 26 March in 2027, the Conch Republic Independence Celebration takes over from 16 to 25 April, and the ferry has maintenance days on 17 March and 23 April 2027.
May and June. The shoulder, and a good pair of months. The wind drops, the water passes 85°F, and the rains begin to build. The refuge puts the peak of tarpon season here, as large tarpon move back into the channels and flats, and Key deer fawns appear. Hurricane season starts on 1 June.
July and August. Hot and calm. Highs of about 90°F, the warmest water of the year at 88 to 89, and the latest sunsets, around 8:20 p.m. at the start of July. Hemingway Days is in late July, and the lobster sport season falls on the last Wednesday and Thursday of the month, 28 and 29 July in 2027, with the regular season opening on 6 August. The Garden Club closes Wednesdays and Thursdays from early July.
September. The wettest month, 7.24 inches on average, and the heart of hurricane season; NOAA puts its peak day at 10 September. The case for coming, and the one booking to be careful with, are on the hurricane season page. The refuge calls September and October peak southbound bird migration, with record numbers of peregrine falcons.
October. Still warm and wet, highs about 86°F, and in 2026 the island’s big festival, Fantasy Fest, runs from 16 to 25 October. The Dry Tortugas ferry sails every day from 14 to 31 October except the 22nd and 23rd, and the dates are going: on 13 October the 14th to the 17th, the 26th and the 28th were sold out, so book the Tortugas now. Book lodging early if you are coming for the festival. Honest Eco’s dolphin sunset sail is back from 15 October.
November. The season turns. The rain drops to about two inches, the water cools toward 78°F, and hurricane season ends on the 30th. The ferry has a maintenance day on 24 November 2026.
So when should you go?
- For the weather and the full menu of trips: December to April. Book the Dry Tortugas and the small sunset boats first; this is when they sell out. The ferry checks in at 7 a.m., so sleep within a walk of it the night before.
- For snorkeling and fishing in calm water: May to August, with the reef trip early in your stay and an eye on the tropics.
- For lower prices: May to October, the state’s own off-season at Bahia Honda, and May in particular, before the heat and the storms build.
- For a party: Fantasy Fest, 16 to 25 October 2026 or 22 to 31 October 2027. In 2026 the Tortugas ferry sails on eight of the festival’s ten days, all but the 22nd and 23rd, and the 16th and 17th were sold out by 13 October.
Whatever the month, the things-to-do page has each sight’s hours and the one fact that decides it.
.jpg){kind=link}