Climate and average weather in Key West
In Key West, the summers are oppressive, hot, wet, and partly cloudy and the winters are warm, breezy, and mostly clear.
Over the course of the year, the temperature in Key West typically varies from 69°F to 84°F, and is rarely below 61°F or above 86°F. August is the hottest month of the year, while January is the coldest.
Based on the travel score, the best times of year to visit Key West for warm-weather activities are from early January to late May and late October to late December.
- Hottest
- Aug
- 84°
- Coldest
- Jan
- 69°
- Wettest
- Sep
- 5.4 in
- Driest
- Mar
- 1.0 in
- Rain / yr
- 31.3 in
- 109 wet days
- Daylight
- 10.5–13.5 h
- shortest–longest
- Elevation
- 3 ft
- 24.6°N
- Clearest
- Mar
- 32% cloud
Key West is county seat of Monroe County, Florida, United States.
- Density
- 1,373/km²
- people per km²
- Founded
- 1828
Air quality: WHO Ambient Air Quality Database. Density & description: Wikidata (CC0), GeoNames.
Key West weather by month, at a glance
The whole year in one picture — sky, rain, humidity, temperature and travel score. Click any band to jump to its full chart.
Each stripe is one measure across the whole year, stacked so a single day reads top to bottom. The sky band runs overcast grey on top down to clear blue at the base — more blue means sunnier — followed by the rainfall curve, the humidity band, a temperature strip that tints each stretch of the year by how warm its average high is, and the travel-score line at the foot. Scan straight down any date to read that day across every measure at once; the score climbs highest around early January to late May.
Temperature through the year
Daily average highs and lows in Key West, from 1991–2020 of climate data. The shaded bands show the range most days fall in — 10th to 90th percentile.
Temperatures in Key West stay fairly even through the year, without a distinct hot or cool season. The warmest month is August, with an average high of 84°F and low of 81°F; the coolest is January, with an average low of 69°F and high of 73°F.
Days typically run about 3°F warmer than nights year-round.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg high (°F) | 73 | 73 | 74 | 77 | 80 | 83 | 84 | 84 | 83 | 81 | 77 | 75 |
| Avg low (°F) | 69 | 70 | 71 | 74 | 77 | 80 | 81 | 81 | 80 | 78 | 74 | 71 |
| Avg high (°F) | Avg low (°F) | |
|---|---|---|
| Jan | 73 | 69 |
| Feb | 73 | 70 |
| Mar | 74 | 71 |
| Apr | 77 | 74 |
| May | 80 | 77 |
| Jun | 83 | 80 |
| Jul | 84 | 81 |
| Aug | 84 | 81 |
| Sep | 83 | 80 |
| Oct | 81 | 78 |
| Nov | 77 | 74 |
| Dec | 75 | 71 |
How hot and cold Key West really feels
The felt-temperature range through the year — heat index on the day's high (summer humidity), wind chill on the night's low (winter wind). The dashed lines are the plain thermometer; the gap is how much hotter or colder it really feels.
On the hottest afternoons, once humidity is folded in, Key West feels like about 95°F (around August 17). About 105 days a year carry some heat stress, peaking in August.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Feels-like high (°F) | 73 | 73 | 74 | 77 | 81 | 90 | 93 | 94 | 91 | 84 | 77 | 75 |
| Air high (°F) | 73 | 73 | 74 | 77 | 80 | 83 | 84 | 84 | 83 | 81 | 77 | 75 |
| Feels-like low (°F) | 69 | 70 | 71 | 74 | 77 | 80 | 81 | 81 | 80 | 78 | 75 | 72 |
| Air low (°F) | 69 | 70 | 71 | 74 | 77 | 80 | 81 | 81 | 80 | 78 | 74 | 71 |
| Feels-like high (°F) | Air high (°F) | Feels-like low (°F) | Air low (°F) | |
|---|---|---|---|---|
| Jan | 73 | 73 | 69 | 69 |
| Feb | 73 | 73 | 70 | 70 |
| Mar | 74 | 74 | 71 | 71 |
| Apr | 77 | 77 | 74 | 74 |
| May | 81 | 80 | 77 | 77 |
| Jun | 90 | 83 | 80 | 80 |
| Jul | 93 | 84 | 81 | 81 |
| Aug | 94 | 84 | 81 | 81 |
| Sep | 91 | 83 | 80 | 80 |
| Oct | 84 | 81 | 78 | 78 |
| Nov | 77 | 77 | 75 | 74 |
| Dec | 75 | 75 | 72 | 71 |
Average hourly temperature in Key West
A compact picture of the whole year, hour by hour: each column is a day, each row an hour, and the color is the modeled average temperature. Darker overlays mark night, lighter ones the civil-twilight hours around sunrise and sunset.
Read left to right for the day of the year and top to bottom for the hour of the day; the color is the modeled temperature, cool blues through to hot reds on the same scale as the other charts. A vertical slice is a single day's swing — coolest just before dawn, warmest in the mid-afternoon — while a horizontal slice follows one hour across the seasons. The darker overlay marks night and the lighter one the twilight around sunrise and sunset. Colors run warmest on August afternoons, near 84°F, and coldest before dawn in January, near 69°F.
Key West weather by month
Every month at a glance. Click a month for its detailed page.
| Month | High / Low (°F) | Rainfall (inches) | Wet days | Daylight (hours) | Travel score |
|---|---|---|---|---|---|
| Jan | 73° / 69° | 1.5 | 5.7 | 10.6 | 7.8 |
| Feb | 73° / 70° | 1.2 | 4 | 11.1 | 8.1 |
| Mar | 74° / 71° | 1.0 | 4.2 | 11.8 | 8.4 |
| Apr | 77° / 74° | 1.5 | 4.5 | 12.6 | 8.3 |
| May | 80° / 77° | 2.6 | 7.9 | 13.2 | 7.3 |
| Jun | 83° / 80° | 4.1 | 12.7 | 13.5 | 5.7 |
| Jul | 84° / 81° | 2.5 | 12.9 | 13.4 | 5.3 |
| Aug | 84° / 81° | 4.1 | 16.1 | 12.9 | 4.8 |
| Sep | 83° / 80° | 5.4 | 17.7 | 12.2 | 4.7 |
| Oct | 81° / 78° | 4.6 | 12.7 | 11.4 | 6.2 |
| Nov | 77° / 74° | 1.5 | 5.8 | 10.8 | 7.8 |
| Dec | 75° / 71° | 1.3 | 5.1 | 10.5 | 8.0 |
Chance of rain
How likely it is to rain on a typical day, and how that shifts across the wetter and drier seasons.
Key West gets about 31.3 in of precipitation a year. On a typical day the chance of rain is some rain, but that rises and falls sharply with the seasons.
The wetter season lasts 5.3 months, from around May 21 to Oct 28, peaking in September at about 62% chance on a given day. The drier stretch runs the rest of the year, bottoming out around Mar 31.
September is the wettest month by volume, with 5.4 in over about 18 wet days; March is the driest, with 1.0 in.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Rain on a day (%) | 18 | 14 | 14 | 15 | 26 | 42 | 42 | 51 | 59 | 41 | 20 | 17 |
| Rain days | 6 | 4 | 4 | 5 | 8 | 13 | 13 | 16 | 18 | 13 | 6 | 5 |
| Rain on a day (%) | Rain days | |
|---|---|---|
| Jan | 18 | 6 |
| Feb | 14 | 4 |
| Mar | 14 | 4 |
| Apr | 15 | 5 |
| May | 26 | 8 |
| Jun | 42 | 13 |
| Jul | 42 | 13 |
| Aug | 51 | 16 |
| Sep | 59 | 18 |
| Oct | 41 | 13 |
| Nov | 20 | 6 |
| Dec | 17 | 5 |
Monthly rainfall
Over a full year, Key West collects about 31.3 in of rain across 109 wet days — roughly 2.6 in in an average month.
It doesn’t fall evenly. September is the wettest month with 5.4 in, while March is the driest at just 1.0 in. The three wettest months alone bring about 45% of the year’s total.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Rainfall (in) | 1.5 | 1.2 | 1.0 | 1.5 | 2.6 | 4.1 | 2.5 | 4.1 | 5.4 | 4.6 | 1.5 | 1.3 |
| Rain days | 6 | 4 | 4 | 5 | 8 | 13 | 13 | 16 | 18 | 13 | 6 | 5 |
| Rainfall (in) | Rain days | |
|---|---|---|
| Jan | 1.5 | 6 |
| Feb | 1.2 | 4 |
| Mar | 1.0 | 4 |
| Apr | 1.5 | 5 |
| May | 2.6 | 8 |
| Jun | 4.1 | 13 |
| Jul | 2.5 | 13 |
| Aug | 4.1 | 16 |
| Sep | 5.4 | 18 |
| Oct | 4.6 | 13 |
| Nov | 1.5 | 6 |
| Dec | 1.3 | 5 |
Clouds and sunshine
How often the daytime sky is clear, partly cloudy or overcast.
In Key West, the average share of the sky covered by clouds shows significant seasonal variation over the course of the year.
The clearer part of the year begins around January 24 and lasts for 4.0 months, ending around May 25. The clearest month is March, when the sky is clear, mostly clear, or partly cloudy 81% of the time on average.
The cloudier part of the year begins around May 26 and lasts for 5.0 months, ending around October 23. The cloudiest month is September, when it is overcast or mostly cloudy 52% of the time.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Clearer (%) | 67 | 76 | 81 | 80 | 72 | 53 | 50 | 50 | 48 | 62 | 73 | 71 |
| Cloudier (%) | 33 | 24 | 19 | 20 | 28 | 47 | 50 | 50 | 52 | 38 | 27 | 29 |
| Clearer (%) | Cloudier (%) | |
|---|---|---|
| Jan | 67 | 33 |
| Feb | 76 | 24 |
| Mar | 81 | 19 |
| Apr | 80 | 20 |
| May | 72 | 28 |
| Jun | 53 | 47 |
| Jul | 50 | 50 |
| Aug | 50 | 50 |
| Sep | 48 | 52 |
| Oct | 62 | 38 |
| Nov | 73 | 27 |
| Dec | 71 | 29 |
Daylight, sunrise and sunset
Hours of daylight through the year, with sunrise and sunset times.
The gold band is daylight — sunrise runs along its lower edge, sunset along the upper — so it widens toward summer and pinches toward winter, with night the dark area above and below. The longest day, around June 6, brings about 13 h 30 min of light; the shortest, around January 1, only 10 h 30 min — a swing of roughly 3 hours.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Daylight (h) | 10.6 | 11.1 | 11.8 | 12.6 | 13.2 | 13.5 | 13.4 | 12.9 | 12.2 | 11.4 | 10.8 | 10.5 |
| Sunrise (AM) | 7:17 | 7:07 | 6:42 | 6:10 | 5:48 | 5:42 | 5:51 | 6:05 | 6:17 | 6:30 | 6:49 | 7:09 |
| Sunset (PM) | 5:55 | 6:16 | 6:31 | 6:45 | 6:59 | 7:13 | 7:14 | 6:57 | 6:26 | 5:55 | 5:36 | 5:38 |
| Daylight (h) | Sunrise (AM) | Sunset (PM) | |
|---|---|---|---|
| Jan | 10.6 | 7:17 | 5:55 |
| Feb | 11.1 | 7:07 | 6:16 |
| Mar | 11.8 | 6:42 | 6:31 |
| Apr | 12.6 | 6:10 | 6:45 |
| May | 13.2 | 5:48 | 6:59 |
| Jun | 13.5 | 5:42 | 7:13 |
| Jul | 13.4 | 5:51 | 7:14 |
| Aug | 12.9 | 6:05 | 6:57 |
| Sep | 12.2 | 6:17 | 6:26 |
| Oct | 11.4 | 6:30 | 5:55 |
| Nov | 10.8 | 6:49 | 5:36 |
| Dec | 10.5 | 7:09 | 5:38 |
Sunny days
How many genuinely sunny days each month brings — days the sky stays clear or mostly clear — banded into plain-language zones.
Key West averages about 15 sunny days a month — counting the days the sky stays clear or mostly clear — with a clear seasonal swing between 9 and 22 days.
The sunnier stretch runs 5.1 months, from around Dec 26 to May 28. The sunniest month is March, with roughly 21 sunny days (bright).
The greyest month is September, down near 10 sunny days — about 53% fewer than the March peak.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Sunny days | 16 | 17 | 21 | 21 | 19 | 12 | 11 | 11 | 10 | 14 | 17 | 17 |
| Sky | Bright | Bright | Bright | Bright | Bright | Mixed | Mixed | Mixed | Mixed | Mixed | Bright | Bright |
| Sunny days | Sky | |
|---|---|---|
| Jan | 16 | Bright |
| Feb | 17 | Bright |
| Mar | 21 | Bright |
| Apr | 21 | Bright |
| May | 19 | Bright |
| Jun | 12 | Mixed |
| Jul | 11 | Mixed |
| Aug | 11 | Mixed |
| Sep | 10 | Mixed |
| Oct | 14 | Mixed |
| Nov | 17 | Bright |
| Dec | 17 | Bright |
Humidity comfort
Share of days at each humidity comfort level, based on the dew point — the measure that tracks how muggy it actually feels.
Humidity comfort is graded by the dew point — the temperature at which the air would be fully saturated — because it tracks how muggy it actually feels far better than relative humidity does. A low dew point feels dry and crisp; a high one feels sticky and oppressive no matter the reading on a humidity gauge.
In Key West, how humid it feels changes dramatically over the year.
The more humid part of the year lasts 7.0 months, from around April 19 to November 17. The muggiest month is June, when the air feels humid, muggy or worse about 100% of the time.
The most comfortable stretch runs from around November 18 to April 18, and January is the most comfortable month — the air is dry or comfortable 32% of the time.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Dry (%) | 16 | 14 | 9 | 2 | 0 | 0 | 0 | 0 | 0 | 0 | 3 | 9 |
| Comfortable (%) | 16 | 15 | 15 | 9 | 2 | 0 | 0 | 0 | 0 | 2 | 7 | 13 |
| Humid (%) | 21 | 19 | 22 | 19 | 7 | 0 | 0 | 0 | 0 | 6 | 19 | 20 |
| Muggy (%) | 33 | 36 | 34 | 33 | 24 | 2 | 0 | 0 | 1 | 16 | 34 | 35 |
| Oppressive (%) | 13 | 16 | 19 | 34 | 59 | 57 | 41 | 27 | 44 | 55 | 35 | 24 |
| Miserable (%) | 0 | 0 | 1 | 2 | 8 | 41 | 59 | 73 | 54 | 21 | 2 | 0 |
| Dry (%) | Comfortable (%) | Humid (%) | Muggy (%) | Oppressive (%) | Miserable (%) | |
|---|---|---|---|---|---|---|
| Jan | 16 | 16 | 21 | 33 | 13 | 0 |
| Feb | 14 | 15 | 19 | 36 | 16 | 0 |
| Mar | 9 | 15 | 22 | 34 | 19 | 1 |
| Apr | 2 | 9 | 19 | 33 | 34 | 2 |
| May | 0 | 2 | 7 | 24 | 59 | 8 |
| Jun | 0 | 0 | 0 | 2 | 57 | 41 |
| Jul | 0 | 0 | 0 | 0 | 41 | 59 |
| Aug | 0 | 0 | 0 | 0 | 27 | 73 |
| Sep | 0 | 0 | 0 | 1 | 44 | 54 |
| Oct | 0 | 2 | 6 | 16 | 55 | 21 |
| Nov | 3 | 7 | 19 | 34 | 35 | 2 |
| Dec | 9 | 13 | 20 | 35 | 24 | 0 |
Wind
Average wind speed through the year, banded into plain-language speed zones so a number reads as 'breezy' or 'calm' without knowing the scale.
This is the average sustained wind speed at the standard 10 metres above open ground — the steady flow a weather station reports, not the sharper gusts that come and go, which can run half again as fast. It's the number that says whether a place is generally breezy or calm.
Across the year, average wind speed in Key West is typically breezy, near 13 mph, and varies moderately with the seasons.
The windier part of the year lasts 6.9 months, from around Oct 7 to May 5. The windiest month is November, averaging about 15 mph (breezy).
The calmer part of the year runs from around May 6 to Oct 6, with August the calmest month at about 10 mph.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Wind speed (mph) | 15 | 14 | 14 | 13 | 12 | 11 | 10 | 10 | 11 | 14 | 15 | 15 |
| Feels | breezy | breezy | breezy | breezy | light breeze | light breeze | light breeze | light breeze | light breeze | breezy | breezy | breezy |
| Wind speed (mph) | Feels | |
|---|---|---|
| Jan | 15 | breezy |
| Feb | 14 | breezy |
| Mar | 14 | breezy |
| Apr | 13 | breezy |
| May | 12 | light breeze |
| Jun | 11 | light breeze |
| Jul | 10 | light breeze |
| Aug | 10 | light breeze |
| Sep | 11 | light breeze |
| Oct | 14 | breezy |
| Nov | 15 | breezy |
| Dec | 15 | breezy |
Hazard calendar for Key West
When the seasonal hazards worth planning around — the rainy season, tropical-cyclone risk and dust haze — are active through the year.
Key West sits in the Atlantic hurricane belt; the season peaks August–October.
Key West's rainy season runs May–October, when most of the year's rain falls.
Best time to visit Key West
To characterize how pleasant the weather is in Key West throughout the year, we compute two travel scores — one for general sightseeing, one for beach and pool weather.
Around mid January, Key West is still near the start of its best-weather window — great conditions with the peak-season crowds not yet at full swing.
Inferred from the travel-score curve; month-by-month visitor numbers are a planned addition.
The travel score favors clear, rainless days with daytime highs between 64°F and 82°F. Based on this score, the best time of year to visit Key West for general outdoor tourist activities is from late October to late May, with a peak score in the last week of March.
The travel score (filled area), and its constituents: the temperature score (red line), the cloud cover score (blue line), and the precipitation score (green line).
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Travel score (0–10) | 7.8 | 8.1 | 8.4 | 8.3 | 7.3 | 5.7 | 5.3 | 4.8 | 4.7 | 6.2 | 7.8 | 8.0 |
| Rating | ideal | ideal | ideal | ideal | good | good | fair | fair | fair | good | ideal | ideal |
| Travel score (0–10) | Rating | |
|---|---|---|
| Jan | 7.8 | ideal |
| Feb | 8.1 | ideal |
| Mar | 8.4 | ideal |
| Apr | 8.3 | ideal |
| May | 7.3 | good |
| Jun | 5.7 | good |
| Jul | 5.3 | fair |
| Aug | 4.8 | fair |
| Sep | 4.7 | fair |
| Oct | 6.2 | good |
| Nov | 7.8 | ideal |
| Dec | 8.0 | ideal |
The beach/pool score favors clear, rainless days with daytime highs between 75°F and 93°F. Based on this score, the best times of year to visit Key West for hot-weather activities run from mid February to late August and again from early October to early January, with a peak score in the first week of May.
The beach/pool score (filled area), and its constituents: the temperature score (red line), the cloud cover score (blue line), and the precipitation score (green line).
What to pack for Key West, by month
Month by month, what's worth putting in the bag — from the temperature range, rain chance, sun and wind. Tap a month for a quick packing note.
For a warm-season trip around August (highs near 84°F), the essentials are light clothes, rain gear and sun protection. In the cold season around January (highs near 73°F), pack light clothes and a windbreaker.
In August, Key West sees daytime highs around 84°F and nights near 81°F. Pack light clothes, rain gear and sun protection. About 16 days see rain.
Sea temperature near Key West
Average ocean temperature at the nearest coast, month by month, banded into swim-comfort zones — the other half of the beach question.
The sea offshore is warmest in August at about 86°F and coldest in February near 73°F.
The water stays above 68°F all year — warm enough for a swim any month.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Sea temperature (°F) | 73 | 73 | 74 | 77 | 80 | 83 | 85 | 86 | 85 | 83 | 78 | 75 |
| Comfort | Refreshing | Refreshing | Refreshing | Warm | Warm | Tropical | Tropical | Tropical | Tropical | Tropical | Warm | Warm |
| Sea temperature (°F) | Comfort | |
|---|---|---|
| Jan | 73 | Refreshing |
| Feb | 73 | Refreshing |
| Mar | 74 | Refreshing |
| Apr | 77 | Warm |
| May | 80 | Warm |
| Jun | 83 | Tropical |
| Jul | 85 | Tropical |
| Aug | 86 | Tropical |
| Sep | 85 | Tropical |
| Oct | 83 | Tropical |
| Nov | 78 | Warm |
| Dec | 75 | Warm |
UV index (midday) in Key West by month
Clear-sky midday UV index through the year, shaded by the WHO exposure levels — how much sun protection each month calls for.
Under clear skies, the midday UV index in Key West peaks around July 18 at about 12 (extreme) — sunscreen, a hat and midday shade are essential. It bottoms out near December 18 at about 5 (high).
The index reaches 3 or more — the level where the WHO recommends sun protection — every month of the year.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| UV index (midday) | 6 | 8 | 10 | 11 | 11 | 11 | 12 | 12 | 11 | 9 | 6 | 5 |
| Level | High | Very high | Very high | Extreme | Extreme | Extreme | Extreme | Extreme | Extreme | Very high | High | High |
| UV index (midday) | Level | |
|---|---|---|
| Jan | 6 | High |
| Feb | 8 | Very high |
| Mar | 10 | Very high |
| Apr | 11 | Extreme |
| May | 11 | Extreme |
| Jun | 11 | Extreme |
| Jul | 12 | Extreme |
| Aug | 12 | Extreme |
| Sep | 11 | Extreme |
| Oct | 9 | Very high |
| Nov | 6 | High |
| Dec | 5 | High |
Average hourly UV index in Key West
Modeled clear-sky UV for every hour of every day — when in the day sun protection actually matters.
The whole year hour by hour: each column is a day, each row an hour, and the color is the modeled clear-sky UV index — the midday peak scaled down as the sun sits lower in the sky. Darker overlays mark night, lighter ones the civil-twilight hours around sunrise and sunset.
UV falls off far faster than brightness as the sun drops, so even in July the burn window is concentrated in the middle of the day: about 8.5 hours a day reach index 3 (protection recommended), and 6.5 hours reach 6 or more. Mornings and late afternoons stay comparatively gentle year round.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| UV ≥ 3 (h/day) | 5 | 6.5 | 7 | 8 | 8 | 8.5 | 8.5 | 8.5 | 7.5 | 7 | 5.5 | 4.5 |
| UV ≥ 6 (h/day) | 0 | 3.5 | 5 | 5.5 | 6 | 6 | 6.5 | 6 | 5.5 | 4.5 | 1.5 | 0 |
| UV ≥ 3 (h/day) | UV ≥ 6 (h/day) | |
|---|---|---|
| Jan | 5 | 0 |
| Feb | 6.5 | 3.5 |
| Mar | 7 | 5 |
| Apr | 8 | 5.5 |
| May | 8 | 6 |
| Jun | 8.5 | 6 |
| Jul | 8.5 | 6.5 |
| Aug | 8.5 | 6 |
| Sep | 7.5 | 5.5 |
| Oct | 7 | 4.5 |
| Nov | 5.5 | 1.5 |
| Dec | 4.5 | 0 |
Air quality in Key West by month
Average fine-particle pollution (PM2.5) through the year — so you can see which months the air is worst, not just the yearly average.
Air quality in Key West is worst in July — around 18 µg/m³ PM2.5 (moderate), about 4.1× the cleanest month (December, 4 µg/m³).
Modeled monthly averages (CAMS reanalysis, 2015–2024).
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| PM2.5 (µg/m³) | 5 | 5 | 6 | 8 | 9 | 15 | 18 | 16 | 10 | 7 | 5 | 4 |
| Level | Good | Good | Good | Good | Good | Moderate | Moderate | Moderate | Good | Good | Good | Good |
| PM2.5 (µg/m³) | Level | |
|---|---|---|
| Jan | 5 | Good |
| Feb | 5 | Good |
| Mar | 6 | Good |
| Apr | 8 | Good |
| May | 9 | Good |
| Jun | 15 | Moderate |
| Jul | 18 | Moderate |
| Aug | 16 | Moderate |
| Sep | 10 | Good |
| Oct | 7 | Good |
| Nov | 5 | Good |
| Dec | 4 | Good |
Growing season
Key West is frost-free year round — even the coldest nights rarely reach freezing, so there is no start or end to the growing season.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Frost-free chance (%) | 100 | 100 | 100 | 100 | 100 | 100 | 100 | 100 | 100 | 100 | 100 | 100 |
| Frost nights | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
| Frost-free chance (%) | Frost nights | |
|---|---|---|
| Jan | 100 | 0 |
| Feb | 100 | 0 |
| Mar | 100 | 0 |
| Apr | 100 | 0 |
| May | 100 | 0 |
| Jun | 100 | 0 |
| Jul | 100 | 0 |
| Aug | 100 | 0 |
| Sep | 100 | 0 |
| Oct | 100 | 0 |
| Nov | 100 | 0 |
| Dec | 100 | 0 |
Growing degree days
Growing degree days tally heat above 50°F: each day adds however many degrees its average temperature runs over that threshold, and cold days add nothing. Key West banks about 9,926 degree days a year, and the running total — which growers use to time plantings and predict maturity — climbs fastest around August.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Growing degree days (°F·days) | 648 | 597 | 711 | 768 | 882 | 936 | 1,005 | 1,014 | 952 | 919 | 778 | 716 |
| Growing degree days (°F·days) | |
|---|---|
| Jan | 648 |
| Feb | 597 |
| Mar | 711 |
| Apr | 768 |
| May | 882 |
| Jun | 936 |
| Jul | 1,005 |
| Aug | 1,014 |
| Sep | 952 |
| Oct | 919 |
| Nov | 778 |
| Dec | 716 |
Solar energy
Average daily shortwave solar energy reaching the ground, banded into brightness zones so the number means something at a glance.
Solar energy is how much sunlight actually reaches the ground each day, measured in kilowatt-hours per square metre (kWh/m²) — the combined effect of how long the sun is up, how high it climbs, and how much cloud gets in the way. It's the raw fuel a solar panel has to work with: for scale, 1 kWh/m² a day is dim and wintry, while 7+ is desert-bright.
Key West receives about 5.5 kWh/m² a day of solar energy on average — bright — with a clear seasonal swing between 3.6 and 7.0 kWh/m².
The brighter stretch of the year lasts 6.4 months, from around Mar 5 to Sep 15. The brightest month is May, averaging about 6.8 kWh/m² (intense).
The dimmest month is December, down near 3.7 kWh/m² — roughly 46% less than the May peak.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Solar energy (kWh/m²) | 3.9 | 4.8 | 5.9 | 6.8 | 6.9 | 6.5 | 6.7 | 6.3 | 5.5 | 4.7 | 4.1 | 3.7 |
| Level | Moderate | Bright | Bright | Intense | Intense | Intense | Intense | Intense | Bright | Bright | Bright | Moderate |
| Solar energy (kWh/m²) | Level | |
|---|---|---|
| Jan | 3.9 | Moderate |
| Feb | 4.8 | Bright |
| Mar | 5.9 | Bright |
| Apr | 6.8 | Intense |
| May | 6.9 | Intense |
| Jun | 6.5 | Intense |
| Jul | 6.7 | Intense |
| Aug | 6.3 | Intense |
| Sep | 5.5 | Bright |
| Oct | 4.7 | Bright |
| Nov | 4.1 | Bright |
| Dec | 3.7 | Moderate |
Where is Key West?
Key West sits at 24.6°N, 81.8°W, 3 ft above sea level, in United States. The nearest listed city is Marco Island, 96 mi away.
What Key West looks like
Topography around Key West
How much the land rises and falls, and what covers it, within 2, 10 and 50 miles of Key West.
Within 2 miles, the terrain around Key West has only modest variations in elevation — a maximum elevation change of 39 ft around an average of 3 ft above sea level; within 10 miles, only modest variations in elevation — a maximum elevation change of 75 ft; within 50 miles, only modest variations in elevation — a maximum elevation change of 52 ft.
The land around Key West is covered by water (64%) and artificial surfaces (26%) within 2 miles, water (95%) within 10 miles, and water (98%) within 50 miles.
United States travel facts
- Power plugs
- Type A / B
- 120 V · 60 Hz
- Prices
- ≈ 100% of US
- price level, 2025
- GDP per capita
- $90,027
- 2025
- Happiness
- 6.8 / 10
- World Happiness, 2025
- Safe drinking water
- 98%
- of population, 2024
- Homicide rate
- 5.8
- per 100k, 2023
- Road deaths
- 12.7
- per 100k/yr, 2019
- Income group
- High
- World Bank
- Religion
Sources: World Bank, US State Department, World Happiness Report, WHO/UNICEF, EF EPI, CIA World Factbook.
Data sources
Temperature, precipitation, cloud, humidity, wind and solar figures are a 1991–2020 climatology for Key West (24.5552°, -81.7816°, elevation 3 ft), computed from hourly ERA5 reanalysis — contains modified Copernicus Climate Change Service information. Sun figures are astronomical calculations, not observations. City data © GeoNames, CC BY 4.0. Map outlines from Natural Earth (public domain); interactive map © Google. Tropical-cyclone seasons are the published climatological basin seasons (NOAA National Hurricane Center / regional warning centres). Sea temperatures are the NOAA OISST v2.1 1991–2020 monthly climatology (public domain), sampled at the nearest ocean point. UV index is derived from CAMS (Copernicus Atmosphere Monitoring Service) clear-sky UV data — contains modified Copernicus Atmosphere Monitoring Service information. Monthly air-quality (PM2.5) seasonality is from the CAMS EAC4 reanalysis (Copernicus Atmosphere Monitoring Service), scaled to the WHO annual mean where available. Topography is sampled from the Copernicus DEM GLO-90 elevation model (© ESA/Airbus) and ESA WorldCover 2021 land cover (CC BY 4.0).