Weather in Key West in August

Shoulder season. August is shoulder season in Key West — cheaper, quieter, and a genuine gamble. You should expect rain on 26 days of the month, which is more days wet than dry.

August ranks 12 of 12 — near the bottom of Key West's year. January is the month that works, and the swing between the two is 39 points, which is a different holiday rather than a slightly better one.

Rain on 26 of the month's 31 days, 3 of them heavy. At that frequency a wet-weather backup is not a contingency, it is the itinerary — book the indoor things first and treat the clear days as the bonus. Pack for 29.9 °C days and 29.1 °C nights; the spread matters more here than any single number.

What the averages hide

Averages flatten a month, and this one hides a few things: 14 days top 30 °C — hot spells arrive, but they break; the day barely swings — 0.9 °C between the overnight low and the afternoon high. Across the twenty years measured, the hottest August day reached 31.4 °C and the coldest night fell to 26.6 °C, and the wettest single day dropped 74 mm — roughly 47% of the month's rain in one day.

August is moderately variable: 17 mm in the driest year against 304 mm in the wettest, around an average of 156 mm. Roughly two Augusts in three land near that average, and the third does something else entirely.

Wind is light at 13.8 km/h, so the temperature on the page is close to the temperature on your skin, and humidity runs at 75%, high enough to notice on the warm days without dominating them.

How August sits in the year

Temperatures hold steady either side: 29.5 °C in July, 29.9 here, 29.4 in September. Nothing about the timing within the month matters much.

Daylight in August

August is at or near the longest days of Key West's year: 13 hours of daylight, losing 0.6 hours across the month. Evenings are the real gain — dinner outdoors still happens in full light.

Sea temperature

The sea sits at about 29.9 °C in August — warm enough that the water offers no relief from the heat. This is the warmest the water gets all year.

How busy it gets

Off season. The genuine off season: cheapest by a distance, with the caveat that some tours and restaurants close entirely.

Crowd levels are estimated from climate desirability and school-holiday calendars, not from visitor numbers.

August in Key West versus nearby

If Key West is one option among several, the nearby comparison is worth making. Miami is close enough to be a coin toss — within a degree on temperature, 1 day more rain. Cape Coral is close enough to be a coin toss — within a degree on temperature, 3 days more rain.

So: August is a compromise. January is 39 points better and is what Key West is actually like at its best — worth moving the trip for if that is possible, and worth adjusting expectations for if it is not.

Every month in Key West

See all twelve months in Key West, or where else to go in August.