Climate in Key West, Florida: Monthly Weather Averages
Key West sits at 4 feet above sea level, and its climate, as recorded at the Key West International Airport, FL station, runs to a yearly mean of 78.9°F. The warmest month is August, averaging 85.5°F with typical highs of 90.6°F; the coldest is January, averaging 70.6°F with lows around 65.5°F. Across a normal year the city receives 40.4 in of precipitation. The full month-by-month picture below comes from the official 1991–2020 U.S. Climate Normals — the 30-year averages the National Weather Service itself uses — so it describes the Key West climate you should actually plan around, whether you are timing a visit, weighing a move, or just settling an argument about which month is best.
Key West climate month by month
The table below is the complete 1991–2020 normals profile for Key West: average high, average low and mean temperature, rainfall, and snowfall for every month. Read down the Mean column to feel the year's rhythm — Key West's temperature range runs from 70.6°F in January to 85.5°F in August.
| Month | Avg High (°F) | Avg Low (°F) | Mean (°F) | Rain (in) | Snow (in) |
|---|---|---|---|---|---|
| January | 75.8 | 65.5 | 70.6 | 1.83 | — |
| February | 77.4 | 67.1 | 72.3 | 1.54 | — |
| March | 79.6 | 69.3 | 74.4 | 1.53 | — |
| April | 82.6 | 73.1 | 77.9 | 2.07 | — |
| May | 85.9 | 76.4 | 81.1 | 3.12 | — |
| June | 88.7 | 79.4 | 84.1 | 4.23 | — |
| July | 90.2 | 80.6 | 85.4 | 3.63 | — |
| August | 90.6 | 80.5 | 85.5 | 5.37 | — |
| September | 89.0 | 79.2 | 84.1 | 7.24 | — |
| October | 85.8 | 76.8 | 81.3 | 5.67 | — |
| November | 81.0 | 72.2 | 76.6 | 2.05 | — |
| December | 77.7 | 68.3 | 73.0 | 2.16 | — |
| Year | 83.7 | 74.0 | 78.9 | 40.44 | — |
How to read the colors:below freezingcoldcoolmildwarmhot. Bands are colored by each cell's own temperature, so a whole year reads at a glance.
NOAA does not publish monthly snowfall normals for this station, so the snow column is shown as —; the temperature and precipitation normals for this station are complete.
Key West through the seasons
Winter in Key West averages highs of 75.8–77.7°F and lows of 65.5–68.3°F, a seasonal mean of 72.0°F. The three months together bring 5.5 in of precipitation — about 14% of the city's yearly total — with December the wettest of the three at 2.16 in. This is the city's gentle season — the coolest quarter of the year still averages shirt-sleeve afternoons, which is exactly why it draws winter visitors.
Spring in Key West averages highs of 79.6–85.9°F and lows of 69.3–76.4°F, a seasonal mean of 77.8°F. The three months together bring 6.7 in of precipitation — about 17% of the city's yearly total — with May the wettest of the three at 3.12 in. The season is a transition: the average temperature climbs 6.7°F from March to May, and by late spring Key West is firmly into warm territory, with May rainfall of 3.12 in to plan around.
Summer in Key West averages highs of 88.7–90.6°F and lows of 79.4–80.6°F, a seasonal mean of 85.0°F. The three months together bring 13.2 in of precipitation — about 33% of the city's yearly total — with August the wettest of the three at 5.37 in. Summers are hot in the classic sense — most afternoons reach the 90s, and shade, water, and air conditioning shape the daily routine.
Fall in Key West averages highs of 81.0–89.0°F and lows of 72.2–79.2°F, a seasonal mean of 80.7°F. The three months together bring 15.0 in of precipitation — about 37% of the city's yearly total — with September the wettest of the three at 7.24 in. Temperatures ease off through the season — the monthly mean drops 7.5°F from September to November — and fall is when Key West's weather turns cooler and wetter, while nights stay mostly frost-free into December.
Best and worst months to visit Key West
Ranking every month by its normals — mild mean temperatures score best, heavy rain and snow count against — the most comfortable months to visit Key West are:
JanuaryFebruaryDecember
January leads the list: average highs of 75.8°F, lows of 65.5°F, and 1.83 in of rain. The other picks, February and December, offer the same balance in Key West's mild stretch of the year. At the other end, September is usually the month to avoid — the year's heaviest rain, with a mean temperature of 84.1°F and 7.24 in of precipitation.
How Key West compares
Across the 114 cities in our dataset, the typical city averages 57.8°F for the year and 35.7 in of precipitation. Key West runs 21.1°F warmer than that typical city and wetter by 4.8 in a year, ranking #1 of 114 for annual warmth and #51 of 114 for precipitation (wettest first). Its year-round temperature swing — warmest month minus coldest — is 14.9°F, which puts it in the mild, ocean- or latitude-softened camp.
Within Florida, Key West is the warmest of the cities we track. See the Florida climate overview for the full state comparison, including Key West (warmest, 78.9°F yearly mean) and Jacksonville (coolest, 69.2°F).
Planning notes for Key West
For anyone relocating: average lows never drop below freezing in any month, so hard freezes are events, not seasons; 2 months average highs of 90°F or more, making air conditioning a core cost of summer life; days and nights differ by only 9.7°F on average, a sign of strong water or coastal moderation; 6 months of the year average between 55°F and 80°F, the band most people find comfortable without heating or cooling. Those four facts, all straight from the normals table above, shape everything from a Key West wardrobe to its utility bills.
Key West climate FAQ
What is the warmest month in Key West?
August is the warmest month in Key West, with a mean temperature of 85.5°F, average highs of 90.6°F and average lows of 80.5°F (1991–2020 normals).
What is the coldest month in Key West?
January is the coldest month, averaging 70.6°F, with highs of 75.8°F and lows of 65.5°F.
How much rain does Key West get in a year?
Key West averages 40.44 in of precipitation a year. The wettest month is September (7.24 in) and the driest is March (1.53 in).
When is the best time of year to visit Key West?
By the normals, the most comfortable months are January, February, December — mild average temperatures with moderate rainfall. September is typically the least comfortable month.
Source: 1991–2020 U.S. Climate Normals, NOAA National Centers for Environmental Information (NCEI) — ncei.noaa.gov. Station: Key West International Airport, FL (USW00012836), elevation 4 ft. Figures checked October 2026.