The Florida Keys
Key West Water Temperature
Flats, harbor tarpon, and blue water at the end of the road.
Sea-surface temperature
Very warmHolding steady · last two weeks
That is about 2°F warmer than average for this time of year, and holding steady over the last two weeks. The November average here is 81°F.
Updated Saturday, November 7 — sea-surface temperature modeled for Key West by Open-Meteo.
For swimming
Very warm
Bath-warm. Pleasant, though it stops being much relief from the heat of the day.
For fishing
Hot — fish the edges of the day
Early and late is the play. Through the middle of the day fish drop into deeper channels and passes where there's moving water and more oxygen.
The last two weeks
| Date | Average |
|---|---|
| Oct 25 | 82.8°F |
| Oct 26 | 82.8°F |
| Oct 27 | 82.6°F |
| Oct 28 | 82.6°F |
| Oct 29 | 83.3°F |
| Oct 30 | 83.5°F |
| Oct 31 | 83.5°F |
| Nov 1 | 83.3°F |
| Nov 2 | 83.1°F |
| Nov 3 | 82.9°F |
| Nov 4 | 82.6°F |
| Nov 5 | 82.8°F |
| Nov 6 | 82.8°F |
| Nov 7 | 82.8°F |
Key West water temperature by month
Averaged from 3 years of daily sea-surface temperature (2023–2025). The range column is the coolest and warmest daily average recorded in that month over the period — a guide to how much any given year can differ, not a record high and low.
| Month | Range | Average |
|---|---|---|
JanJanuary Warm | 68–79°F | 75°F |
FebFebruary Warm | 69–79°F | 76°F |
MarMarch Warm | 72–80°F | 77°F |
AprApril Warm | 75–82°F | 79°F |
MayMay Very warm | 79–87°F | 83°F |
JunJune Very warm | 83–88°F | 86°F |
JulJuly Bath water | 85–90°F | 88°F |
AugAugust Bath water | 85–90°F | 88°F |
SepSeptember Very warm | 85–90°F | 87°F |
OctOctober Very warm | 81–86°F | 84°F |
NovNovembernow Warm | 76–83°F | 81°F |
DecDecember Warm | 70–81°F | 77°F |
Warmest
88°FJuly
Coolest
75°FJanuary
Warmest on average in July at 88°F; coolest in January at 75°F.
The water at Key West
Key West, at the end of the island chain, offers everything: tarpon in the harbor and channels, permit and bonefish on the surrounding flats, yellowtail snapper and grouper on the reef, and sailfish, tuna, and mahi in the deep water a short run out. The Marquesas and backcountry to the west add legendary flats. It's arguably the most complete saltwater fishery in the country.
the harbor & the reef
What moves the water temperature here
The Gulf shelf off this coast is shallow, which is why the water swings so much more between summer and winter than open ocean at the same latitude does. Shallow water heats fast and gives that heat up fast: a single strong winter cold front can pull the inshore bays several degrees down in a couple of days, while the beaches a mile offshore barely move. Wind direction matters too — a sustained offshore breeze can pull cooler water up from below and drop the beach temperature noticeably in a morning.
Inshore bays, canals and flats run warmer than the beach through the summer and colder through the winter, for the same reason. The reading above is for the open water at Key West; expect the back bays to be a few degrees either side of it depending on the season.
Common questions
- What is the water temperature at Key West right now?
- The water at Key West is currently about 83°F (28°C). The November average here is 81°F.
- Is the water warm enough to swim at Key West in November?
- November averages 81°F at Key West, which most people would call warm. About as good as it gets — warm enough to stay in for hours without getting chilled.
- When is the water warmest at Key West?
- July is the warmest month on average at 88°F, and January the coolest at 75°F. 12 months of the year average 75°F or above.
- Why does the water temperature change so quickly here?
- The Gulf shelf off this coast is shallow, so it heats and cools far faster than deep open ocean. A strong winter cold front can pull the inshore water down several degrees in a couple of days, and a sustained offshore wind can drop beach temperatures in a single morning by pulling cooler water up from below.