Month by month
| Month | Afternoon | Sea | Rain | Verdict |
|---|---|---|---|---|
| January | 22.8 °C | 23.2 °C | 8 days | Pleasant — a good time to go |
| February | 23.3 °C | 22.9 °C | 6 days | Pleasant — a good time to go |
| March | 24.4 °C | 24.3 °C | 4 days | Ideal — one of the best times of year |
| April | 25.8 °C | 25.7 °C | 7 days | Ideal — one of the best times of year |
| May | 27.2 °C | 27.4 °C | 11 days | Ideal — one of the best times of year |
| June | 28.7 °C | 29 °C | 16 days | Possible, with trade-offs |
| July | 29.7 °C | 30.4 °C | 15 days | Possible, with trade-offs |
| August | 29.8 °C | 30.5 °C | 18 days | Possible, with trade-offs |
| September | 29.3 °C | 30.1 °C | 19 days | Unfavourable season |
| October | 27.9 °C | 28.5 °C | 16 days | Possible, with trade-offs |
| November | 26 °C | 26.5 °C | 9 days | Ideal — one of the best times of year |
| December | 24.1 °C | 24.5 °C | 7 days | Ideal — one of the best times of year |
Nearby in May
Before you go
Three things to check once you have picked your dates.
Entry
No visa, but an electronic travel authorisation (ESTA) must be obtained online before departure. Passport valid until your return date. Apply for ESTA on the official website or app; not available if you visited Cuba since 2021 or Iran, Iraq, Libya, North Korea, Somalia, Sudan, Syria or Yemen.
For a British passport, per the UK Foreign Office on 18 August 2026. Rules change: check before booking.
Safety
No specific restrictions
Usual precautions apply.
Official advice updated 18 August 2026
Health
Vaccines · Routine vaccines up to date (measles in particular).
Yellow fever · No yellow fever locally, vaccine not recommended. No entry requirement.
Malaria · None.
Per the CDC (page reviewed 26 June 2024); see a travel clinic a few weeks before departure.
Beau Fixe is not a safety or health authority. These notes summarise dated public texts and link to their source: France Diplomatie (Licence Ouverte 2.0), Foreign, Commonwealth & Development Office (gov.uk, Open Government Licence v3.0), Centers for Disease Control and Prevention (Source: CDC). Only the competent authorities are authoritative.
FAQ
Can you swim in Key West in May?
The sea averages 27.4°C in May — yes, pleasant swimming.
How hot is Key West in May?
Expect 27.2°C in the afternoon and 25.5°C at night, averaged over the last 10 years.
Does it rain a lot in Key West in May?
Around 11 days with rain (≥ 1 mm) in the month — 35% of days.