September weather forecastKey Largo, FL
September
Weather in September
Key Largo moves towards fall in September, experiencing a slight dip in temperatures compared to August. However, the weather remains largely warm, keeping up the tropical vibes of the island city. Daylight hours start decreasing, yet the sea maintains its warmth, owing to the summer's residual heat. The frequency of rainfall begins to taper off by the end of this month. Temperatures hit a peak of 84.6°F (29.2°C) in September, and rainfall measures approximately 4.25" (108mm).Temperature
Key Largo's average high-temperature in September is a still moderately hot 84.6°F (29.2°C), marking an insignificant difference from the 85.5°F (29.7°C) of August. Key Largo in September experiences a minor decline in temperature, with an average low of 81.7°F (27.6°C) at night.Heat index
The heat index in September is estimated at a tropical 93.2°F (34°C). Take special precautions - heat exhaustion and heat cramps are expected. Heatstroke may occur with lengthy activity.From a standpoint of the heat index, values pertain to shaded conditions and mild breezes. Direct sunlight might cause an increase of up to 15 Fahrenheit (8 Celsius) degrees in the heat index.
Note: The heat index, also known as 'real feel' or 'apparent temperature', provides an understanding of perceived warmth by combining temperature and relative humidity. Metabolic differences, pregnancy status, and the level of physical activity are additional factors influencing an individual's weather perception. Consider that direct sun exposure can intensify the felt heat, adding potentially 15 Fahrenheit (8 Celsius) degrees to the heat index. Heat index values remain especially vital for babies and toddlers. Young children typically face greater hazards than adults because they do not sweat as much. Their larger skin surface in comparison to their little bodies and the high heat production from their active nature compounds their vulnerability.
Humidity
The average relative humidity in September is 74%.Rainfall
In September, the rain falls for 22.9 days. Throughout September, 4.25" (108mm) of precipitation is accumulated. In Key Largo, during the entire year, the rain falls for 190.1 days and collects up to 27.05" (687mm) of precipitation.Ocean temperature
In September, the average ocean temperature is 85.6°F (29.8°C).Note: For any water activity, having surface water temperatures from 77°F (25°C) to 84.2°F (29°C) is considered outstanding and highly delightful for lengthened periods.
Daylight
In September, the average length of the day is 12h and 17min.On the first day of the month, sunrise is at 7:02 am and sunset at 7:40 pm. On the last day of September, sunrise is at 7:13 am and sunset at 7:09 pm EDT.
Sunshine
In Key Largo, the average sunshine in September is 9h.UV index
April through October, with an average maximum UV index of 7, are months with the highest UV index. A UV Index estimate of 6 to 7 represents a high health vulnerability from unsafe exposure to UV radiation for average individuals.Note: A maximum high daily UV index of 7 during September translates into the following directions:
Guard against overexposure. Protection from sun-induced harm is essential. Limit direct sun exposure and seek shade between 10 a.m. and 4 p.m., the time of the most intense UV radiation, noting that shade structures may not provide total sun protection. Loose clothes with a tight weave are optimal for safeguarding yourself against the Sun's rays. Caution! The reflection of sand and water significantly amplifies the Sun's UV radiation.
Published by: Weather Atlas | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Average temperature in September
Key Largo, FL
- Average high temperature in September: 84.6°F
The warmest month (with the highest average high temperature) is August (85.5°F).
The month with the lowest average high temperature is January (72.7°F).
- Average low temperature in September: 81.7°F
The month with the highest average low temperature is August (82.9°F).
The coldest month (with the lowest average low temperature) is January (66.9°F).
Average pressure in September
Key Largo, FL
- Average pressure in September: 29.94"Hg
The month with the highest atmospheric pressure is January (30.1"Hg).
The months with the lowest atmospheric pressure are September and October (29.94"Hg).
Average wind speed in September
Key Largo, FL
- Average wind speed in September: 9.4mph
The windiest month (with the highest average wind speed) is January (12.9mph).
The calmest month (with the lowest average wind speed) is July (8.9mph).
Average humidity in September
Key Largo, FL
- Average humidity in September: 74%
The months with the highest relative humidity are February, June and December (76%).
The month with the lowest relative humidity is March (73%).
Average rainfall in September
Key Largo, FL
- Average rainfall in September: 4.25"
The wettest month (with the highest rainfall) is August (4.33").
The driest month (with the least rainfall) is March (0.59").
Average rainfall days in September
Key Largo, FL
- Average rainfall days in September: 22.9 days
The month with the highest number of rainy days is September (22.9 days).
The month with the least rainy days is February (9.7 days).
Average sea temperature in September
Key Largo, FL
- Average sea temperature in September: 85.5°F
The best month for swimming (with the highest average sea temperature) is August (86.5°F).
The coldest month (with the lowest average sea temperature) is February (74°F).
Average daylight in September /
Average sunshine in September
Key Largo, FL
- Average daylight in September: 12h and 18min
The month with the longest days is June (Average daylight: 13h and 42min).
The month with the shortest days is December (Average daylight: 10h and 36min).
- Average sunshine in September: 9h and 0min
The month with the most sunshine is July (Average sunshine: 11h and 0min).
The month with the least sunshine is December (Average sunshine: 6h and 24min).
Average sunshine days in September
Key Largo, FL
- Average sunshine days in September: 5.2 days
The month with the most sunshine days is January (17.3 days).
The month with the least sunshine days is September (5.2 days).
Average UV index in September
Key Largo, FL
- Average UV index in September: 7
The months with the highest UV index are April, May, June, July, August, September and October (UV index 7).
The month with the lowest UV index is January (UV index 5).
Average cloud cover in September
Key Largo, FL
- Average cloud cover in September: 30
The month with the most cloud cover is October (Cloud cover 35).
The month with the least cloud cover is April (Cloud cover 26).
Average visibility in September
Key Largo, FL
- Average visibility in September: 6mi
The months with the highest visibility are January, February, March, April, May, June, July, August, September, October, November and December (6mi).
The months with the lowest visibility are January, February, March, April, May, June, July, August, September, October, November and December (6mi).
