September weather forecastPort Royal, SC
September
Weather in September
September marks the beginning of a gradual transition from summer to fall in Port Royal. The temperatures start to cool down slightly, with averages ranging between 72.5°F (22.5°C) and 85.1°F (29.5°C). Moreover, daylight hours start to shorten, with an average of 12.4 hours per day. Even though temperatures begin to drop, weather remains warm enough for swimming and other water activities until the end of September.Temperature
The arrival of September coincides with an average high-temperature of a moderately hot 85.1°F (29.5°C), indicating a minimal shift from August's 88.9°F (31.6°C). Port Royal experiences a mean low-temperature of 72.5°F (22.5°C) during September.Heat index
In September, the average heat index is appraised at a fiery hot 95°F (35°C). Ensure extra safety steps, heat exhaustion and heat cramps are likely. Long activity might lead to heatstroke.Heat index evaluations are typically in the context of light winds and shaded environments. Heat index values may be hiked up by 15 Fahrenheit (8 Celsius) degrees under direct sunshine.
Note: The heat index, also known as 'feels like' or 'felt air temperature', integrates the air's temperature and its humidity to showcase the felt temperature by people. Depending on the activity and the individual's heat perception, which may vary due to factors including wind, clothing, and metabolic variations, this effect remains subjective. With the sun shining directly, it's crucial to understand that it can increase the heat index by up to 15 Fahrenheit (8 Celsius) degrees. Heat index values are primarily vital for children. Younglings are generally more in peril than adults due to their reduced perspiration. Coupled with a larger skin surface relative to their tiny bodies and greater heat production because of their activity, they become more at risk.
The human body cools itself through perspiration, as excessive warmth is removed from the body through sweat evaporation. Increased relative humidity slows down evaporation, thereby decreasing the rate of heat removal from the body, culminating in a sensation of overheating. Overheating and potential dehydration arise when body heat gain eclipses its release capability.
Humidity
In September, the average relative humidity is 75%.Rainfall
In Port Royal, in September, it is raining for 14.9 days, with typically 2.28" (58mm) of accumulated precipitation. In Port Royal, during the entire year, the rain falls for 154.7 days and collects up to 23.11" (587mm) of precipitation.Snowfall
March through November are months without snowfall.Daylight
In Port Royal, the average length of the day in September is 12h and 22min.On the first day of September in Port Royal, sunrise is at 6:58 am and sunset at 7:46 pm. On the last day of the month, sunrise is at 7:16 am and sunset at 7:08 pm EDT.
Sunshine
In September, the average sunshine is 8.7h.UV index
The average daily maximum UV index in September is 6. A UV Index estimate of 6 to 7 represents a high health risk from exposure to the Sun's UV rays for the average person.Note: The average daily UV index of 6 in September transforms into the following instructions:
Implement precautions and maintain sun safety methods. Avoidance of sunburn is demanded. Be aware that the sun's UV radiation is strongest between 10 a.m. and 4 p.m. and try to reduce direct sun exposure during this period as much as possible. On days when the sun blazes, arm yourself with sunglasses that block UVA and UVB radiation.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Average temperature in September
Port Royal, SC
- Average high temperature in September: 85.1°F
The warmest month (with the highest average high temperature) is July (89.6°F).
The month with the lowest average high temperature is January (57.6°F).
- Average low temperature in September: 72.5°F
The month with the highest average low temperature is August (76.6°F).
The coldest month (with the lowest average low temperature) is January (44.1°F).
Average pressure in September
Port Royal, SC
- Average pressure in September: 29.99"Hg
The month with the highest atmospheric pressure is January (30.14"Hg).
The months with the lowest atmospheric pressure are June and August (29.98"Hg).
Average wind speed in September
Port Royal, SC
- Average wind speed in September: 7mph
The windiest month (with the highest average wind speed) is April (8.2mph).
The calmest month (with the lowest average wind speed) is August (6.5mph).
Average humidity in September
Port Royal, SC
- Average humidity in September: 75%
The month with the highest relative humidity is December (77%).
The month with the lowest relative humidity is March (71%).
Average rainfall in September
Port Royal, SC
- Average rainfall in September: 2.28"
The wettest month (with the highest rainfall) is August (3.54").
The driest month (with the least rainfall) is February (0.87").
Average rainfall days in September
Port Royal, SC
- Average rainfall days in September: 14.9 days
The month with the highest number of rainy days is August (21.8 days).
The month with the least rainy days is November (6.8 days).
Average snowfall days in September
Port Royal, SC
- Average snowfall days in September: 0 days
The month with the highest number of snowfall days is January (0.2 days).
The months with the least snowfall days are March, April, May, June, July, August, September, October and November (0 days).
Average daylight in September /
Average sunshine in September
Port Royal, SC
- Average daylight in September: 12h and 24min
The month with the longest days is June (Average daylight: 14h and 12min).
The month with the shortest days is December (Average daylight: 10h and 6min).
- Average sunshine in September: 8h and 42min
The month with the most sunshine is July (Average sunshine: 11h and 12min).
The month with the least sunshine is December (Average sunshine: 5h and 36min).
Average sunshine days in September
Port Royal, SC
- Average sunshine days in September: 11.4 days
The month with the most sunshine days is November (20.7 days).
The month with the least sunshine days is August (5.3 days).
Average UV index in September
Port Royal, SC
- Average UV index in September: 6
The months with the highest UV index are May, June, July and August (UV index 7).
The month with the lowest UV index is January (UV index 3).
Average cloud cover in September
Port Royal, SC
- Average cloud cover in September: 29
The months with the most cloud cover are February and December (Cloud cover 39).
The month with the least cloud cover is July (Cloud cover 25).
Average visibility in September
Port Royal, SC
- 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).
