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 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
The average high-temperature in September, at a still tropical 86.7°F (30.4°C), reveals a modest deviation from August's 88.3°F (31.3°C). An average low-temperature of 77.5°F (25.3°C) marks the nights throughout September.Heat index
September's heat index is appraised at a sweltering 98.6°F (37°C). Extra safeguards are necessary to prevent heat exhaustion and heat cramps. Prolonged activity might cause heatstroke.Be informed that the heat index values are oriented around shady conditions and gentle breezes. Exposure to the direct sun could elevate the heat index by 15 Fahrenheit (8 Celsius) degrees.
Note: The heat index, also known as 'apparent temperature' or 'felt air temperature', is achieved by amalgamating air temperature with the relative humidity readings. Factors encompassing physical activity, clothing, and metabolic differences have a role in shaping the individual's impression of temperature. Consider the sun's direct rays and their impact; they can potentially increase the heat index by 15 Fahrenheit (8 Celsius) degrees. Heat index values are quite important for children. Young children are more at risk than adults since they tend to sweat less. Moreover, their large skin surface in proportion to their small bodies and the high heat production due to their activities contribute to their vulnerability.
Perspiring is the body's way of cooling down, particularly by allowing sweat to evaporate and take the heat with it. An increase in relative humidity hinders the body's normal cooling function by reducing evaporation, thereby decreasing the rate of body cooling and enhancing the sense of warmth. If heat absorption isn't effectively countered by the body's cooling methods, body temperature surges, hinting at potential problems.
Humidity
In September, the average relative humidity is 75%.Rainfall
In Keystone, during September, the rain falls for 15.7 days and regularly aggregates up to 0.71" (18mm) of precipitation. Throughout the year, there are 120.5 rainfall days, and 9.45" (240mm) of precipitation is accumulated.Daylight
The average length of the day in September is 12h and 19min.On the first day of September, sunrise is at 7:09 am and sunset at 7:51 pm. On the last day of the month, sunrise is at 7:23 am and sunset at 7:17 pm EDT.
Sunshine
In Keystone, the average sunshine in September is 9.2h.UV index
The months with the highest UV index are May through September, with an average maximum UV index of 7. A UV Index of 6 to 7 symbolizes a high health risk from unprotected exposure to Sun's UV rays for ordinary individuals.Note: In September, the maximum UV index of 7 transforms into these recommendations:
Inhibit overexposure. Warding off sun damage is of utmost importance. UV radiation from the Sun is most intense between 10 a.m. and 4 p.m. Try to avoid direct sunlight during this period. By wearing a generously brimmed hat, you can cut UV radiation exposure significantly.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
How hot does it get in September?
What is the average humidity in September?
How much does it rain in September?
How many hours of daylight does Keystone have in September?
What time are sunrise and sunset in September?
How many hours of sunshine does Keystone have in September?
What are the months with the highest UV index?
How high is the UV index in September?
Average temperature in September
Keystone, FL
- Average high temperature in September: 86.7°F
The warmest month (with the highest average high temperature) is August (88.3°F).
The month with the lowest average high temperature is January (66°F).
- Average low temperature in September: 77.5°F
The month with the highest average low temperature is August (80.2°F).
The coldest month (with the lowest average low temperature) is January (54.5°F).
Average pressure in September
Keystone, FL
- Average pressure in September: 29.96"Hg
The month with the highest atmospheric pressure is January (30.14"Hg).
The month with the lowest atmospheric pressure is September (29.96"Hg).
Average wind speed in September
Keystone, FL
- Average wind speed in September: 7.3mph
The windiest months (with the highest average wind speed) are January, March and April (8.9mph).
The calmest month (with the lowest average wind speed) is July (6.7mph).
Average humidity in September
Keystone, FL
- Average humidity in September: 75%
The month with the highest relative humidity is December (77%).
The month with the lowest relative humidity is May (72%).
Average rainfall in September
Keystone, FL
- Average rainfall in September: 0.71"
The wettest month (with the highest rainfall) is July (1.77").
The driest month (with the least rainfall) is March (0.2").
Average rainfall days in September
Keystone, FL
- Average rainfall days in September: 15.7 days
The month with the highest number of rainy days is August (17.9 days).
The month with the least rainy days is November (5.5 days).
Average daylight in September /
Average sunshine in September
Keystone, FL
- Average daylight in September: 12h and 2min
The month with the longest days is June (Average daylight: 13h and 54min).
The month with the shortest days is December (Average daylight: 10h and 24min).
- Average sunshine in September: 9h and 1min
The month with the most sunshine is May (Average sunshine: 11h and 18min).
The month with the least sunshine is December (Average sunshine: 6h and 30min).
Average sunshine days in September
Keystone, FL
- Average sunshine days in September: 10.6 days
The month with the most sunshine days is January (23.4 days).
The month with the least sunshine days is July (6.7 days).
Average UV index in September
Keystone, FL
- Average UV index in September: 7
The months with the highest UV index are May, June, July, August and September (UV index 7).
The month with the lowest UV index is January (UV index 4).
Average cloud cover in September
Keystone, FL
- Average cloud cover in September: 26
The months with the most cloud cover are January and December (Cloud cover 30).
The month with the least cloud cover is May (Cloud cover 20).
Average visibility in September
Keystone, 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).
Keystone, Florida, USA
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