Key Largo, FL weather in September
Expect hot, oppressively humid weather with rain on most days in Key Largo in September, with highs near 91°F and lows near 74°F. Rain falls on about 18 days. Plan outdoor time for mornings and evenings.
- Normal high
- 91°F
- Normal low
- 74°F
- Wet days
- 18
- 9.0 in total
- Muggy days
- 30
- dew point 65°F+
How September changes from start to finish
| September 1 | September 30 | |
|---|---|---|
| Normal high | 92°F | 90°F |
| Normal low | 75°F | 74°F |
| Chance of a wet day | 62% | 54% |
| Sunrise / sunset | 7:02 am / 7:40 pm | 7:13 am / 7:10 pm |
| Daylight | 12.6 h | 11.9 h |
Chance of a wet day: average for the first and last 7 days of the month. Times are local clock time (Eastern Time).
A typical September day
- 6 am77°Fdew point 75°F
- 9 am84°Fdew point 76°F
- Noon86°Fdew point 75°F
- 3 pm86°Fdew point 75°F
- 6 pm82°Fdew point 75°F
- 9 pm80°Fdew point 75°F
NOAA hourly normals (local standard time) from Homestead AFB (28 mi away); average wind 6 mph; clear or few clouds in 43% of daytime hours, mostly cloudy or overcast in 39%.
What kind of days to expect
- Comfortable dayshigh 65-80°F and dew point under 60°F0 of 30
- Beach dayshigh 80-95°F, under 0.05 in of rain, afternoon wind under 15 mph11 of 30
- Hot dayshigh 90°F or more22 of 30
- Muggy daysdaily mean dew point 65°F or more30 of 30
- Wet daysat least 0.01 in of rain or melted snow18 of 30
- Notable rainat least 0.10 in12 of 30
- Freezing nightslow 32°F or below0 of 30
Average days per September, counted from daily records for each year 1991-2020.
Rain in September
Normal precipitation is 9.0 in; a dry September brings about 6.0 in and a wet one about 11.1 in (25th and 75th percentiles). About 5 days bring half an inch or more, and about 3 an inch or more.
How September varies from year to year
- Warmest September, 1991-20201996: average high 96°F
- Coolest September1994: average high 88°F
- Wettest September1998: 18.2 in
- Driest September1993: 3.4 in
- Highest reading105°F (September 2, 2007)
- Lowest reading67°F (September 26, 2019)
From the station's daily records with NOAA quality flags removed; most recent date shown when a reading repeats.
September compared with August and October
| August | September | October | |
|---|---|---|---|
| Normal high | 93°F | 91°F | 88°F |
| Normal low | 74°F | 74°F | 71°F |
| Wet days | 19 | 18 | 13 |
| Comfortable days | 0 | 0 | 1 |
| Daylight | 13.0 h | 12.3 h | 11.6 h |
Highs change by -2°F from August and -3°F into October.
Nearby alternatives in September
- Drier: Port St. Lucie, FL153 mi · high 88°F · 15 wet days
How Key Largo ranks in September
- Normal high33rd warmest of 378 cities; 2nd of 23 in Florida
- Wet days372nd driest of 378
- Comfortable days327th most of 342
What to pack for Key Largo in September
- Light, breathable clothing – highs near 91°F and about 30 muggy days
- A rain jacket or umbrella – rain on about 18 days
- A swimsuit – about 11 beach days
Heating and cooling
September has 0 heating degree days and 533 cooling degree days (base 65°F), 12% of the year's total heating and cooling demand.
Questions
How hot is Key Largo in September?
The normal high is 91°F and the normal low is 74°F. From 1991 to 2020 the hottest September reading was 105°F (September 2, 2007).
Does it rain a lot in Key Largo in September?
About 18 days in September have at least 0.01 in of precipitation, and the normal total is 9.0 in. The wettest September in 1991-2020 was in 1998 (18.2 in); the driest was in 1993 (3.4 in).
Is September a good time to visit Key Largo?
September ranks 12th of 12 months on our comfort score for Key Largo (29 out of 100). It has almost no comfortable days and about 22 days at 90°F or hotter. The best months are January, February and March.
Where the numbers come from
- Temperature, rain and snow depth: Royal Palm RS (USC00087760), 23 mi NNW of the city center, 7 ft . NOAA normals and daily records, 1991-2020.
- Snowfall and frost dates: Tavernier (USC00088841), 7.2 mi SW of the city center, 7 ft . NOAA normals and daily records, 1991-2020.
- Humidity and wind by hour and cloud cover: Homestead AFB (USW00012826), 28 mi N of the city center, 16 ft . NOAA normals and daily records, 1991-2020.
- Daily humidity and wind: Homestead AFB Airport (722026-12826), 28 mi N of the city center, 5 ft . Hourly observations, 1991-2020.