Contents
- Weather in September
- Frequently asked questions
- Average temperature in September
- Average pressure in September
- Average wind speed in September
- Average humidity in September
- Average rainfall in September
- Average rainfall days in September
- Average sea temperature in September
- Average daylight in September
- Average sunshine in September
- Average sunshine days in September
- Average UV index in September
- Average cloud cover in September
- Average visibility in September
Weather in September
Temperature
September's average high-temperature in Key West stands at a still warm 84.4°F (29.1°C), showing little deviation from August's 85.3°F (29.6°C). Key West's September nights experience a subtle temperature dip to an average of 82.2°F (27.9°C).Heat index
For most parts of September, the heat index is appraised at a hot 93.2°F (34°C). Adopt additional preventive measures, heat cramps and heat exhaustion are potential outcomes. Prolonged activity may trigger heatstroke.Data suggests that the heat index is set for environments in shade and with a light wind. Exposure to the sun directly might heighten the heat index by 15 Fahrenheit (8 Celsius) degrees.
Note: The heat index, also known as 'apparent temperature' or 'felt air temperature', is a composite of temperature and humidity figures to convey how warm it feels. The individual's impression of temperature can be shaped by additional aspects such as metabolic variations, physical activity, and clothing. One's exposure to direct sunlight has the potential to intensify the heat sensation, increasing the heat index by up to 15 Fahrenheit (8 Celsius) degrees. Heat index values are highly critical to babies and toddlers. Young ones regularly neglect the requirement for rest and fluid replenishment. Thirst is a late stage of dehydration - so, it is necessary to keep hydrated, particularly during extended periods of physical exertion.
Humidity
July through September, with an average relative humidity of 74%, are the least humid months.Rainfall
The month with the most rainfall in Key West is September, when the rain falls for 23.1 days and typically aggregates up to 5.12" (130mm) of precipitation.Ocean temperature
In Key West, the average seawater temperature in September is 85.6°F (29.8°C).Note: Surface water temperatures ranging from 77°F (25°C) to 84.2°F (29°C) are seen as ideal and highly pleasant for extended enjoyment in all water activities.
Daylight
In Key West, the average length of the day in September is 12h and 17min.On the first day of September in Key West, sunrise is at 7:08 am and sunset at 7:45 pm. On the last day of the month, sunrise is at 7:18 am and sunset at 7:14 pm EDT.
Sunshine
In September, the average sunshine is 9h.UV index
The months with the highest UV index are April through October, with an average maximum UV index of 7. A UV Index reading of 6 to 7 represents a high health risk from exposure to the Sun's UV rays for ordinary individuals.Note: The average daily UV index of 7 in September transforms into the following instructions:
Stand by precautions and apply sun safety measures. Evading sunburn is of great importance. The Sun's UV radiation is most intense from 10 a.m. to 4 p.m. Try to avoid direct sun exposure during these hours. Counter UV radiation's ill effects with clothing designed for sun safety and UV-resistant eyewear. Watch out! Sand and water enhance the UV exposure you receive.
Frequently asked questions
How hot does it get in Key West in September?
What are the least humid months in Key West?
What is the average humidity in September in Key West?
What is the rainiest month in Key West?
How many days does it rain in September in Key West?
What is the ocean temperature in September in Key West?
How many hours of daylight does Key West have in September?
What time are sunrise and sunset in September in Key West?
How many hours of sunshine does Key West have in September?
What is the month with the highest UV index in Key West?
What is the UV index intensity in September in Key West?
Average temperature in September
Key West, FL
- Average high temperature in September: 84.4°F
The warmest month (with the highest average high temperature) is August (85.3°F).
The month with the lowest average high temperature is January (72.7°F).
- Average low temperature in September: 82.2°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 (68.5°F).
Average pressure in September
Key West, FL
- Average pressure in September: 29.93"Hg
The month with the highest atmospheric pressure is January (30.09"Hg).
The months with the lowest atmospheric pressure are September and October (29.93"Hg).
Average wind speed in September
Key West, FL
- Average wind speed in September: 10.3mph
The windiest months (with the highest average wind speed) are January and November (14.4mph).
The calmest month (with the lowest average wind speed) is July (9.5mph).
Average humidity in September
Key West, FL
- Average humidity in September: 74%
The month with the highest relative humidity is February (78%).
The months with the lowest relative humidity are July, August and September (74%).
Average rainfall in September
Key West, FL
- Average rainfall in September: 5.12"
The wettest month (with the highest rainfall) is September (5.12").
The driest month (with the least rainfall) is March (0.67").
Average rainfall days in September
Key West, FL
- Average rainfall days in September: 23.1 days
The months with the highest number of rainy days are August and September (23.1 days).
The month with the least rainy days is February (11 days).
Average sea temperature in September
Key West, FL
- Average sea temperature in September: 85.6°F
The best month for swimming (with the highest average sea temperature) is August (86.9°F).
The coldest months (with the lowest average sea temperature) are January and February (71.2°F).
Average daylight in September /
Average sunshine in September
Key West, FL
- Average daylight in September: 12h and 2min
The month with the longest days is June (Average daylight: 13h and 36min).
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 18min).
Average sunshine days in September
Key West, FL
- Average sunshine days in September: 4.5 days
The month with the most sunshine days is March (17 days).
The month with the least sunshine days is September (4.5 days).
Average UV index in September
Key West, 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 West, FL
- Average cloud cover in September: 29
The month with the most cloud cover is January (Cloud cover 34).
The month with the least cloud cover is April (Cloud cover 23).
Average visibility in September
Key West, 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).
Key West, Florida, USA
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