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 snowfall in September
- Average snowfall 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
Entering September, Johnston's average high-temperature reads a moderately hot 84.7°F (29.3°C), indicating a close resemblance to the previous month's climate. In September, Johnston encounters an average low-temperature of 66.4°F (19.1°C) during the night.Heat index
September's heat index is computed to be a hot 93.2°F (34°C). Greater safety measures are needed, risk of heat exhaustion and heat cramps is high. Continuous activity might trigger heatstroke.It is noted that heat index values are ascertained for locations in the shade and with gentle breezes. Direct sunlight might lead to a heat index increase by up to 15 Fahrenheit (8 Celsius) degrees.
Note: The heat index, also known as 'felt air temperature' or 'real feel', stands as a testimony to how temperature and humidity combine to impact our sense of warmth. The effect is personal, with varied weather perceptions among individuals due to differences in body mass, stature, and physical activity. 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 babies and toddlers. Children often fail to recognize the requirement to rest and rehydrate. Thirst, being a late symptom of dehydration, underlines the importance of maintaining hydration, especially during ongoing physical activities.
Humidity
The average relative humidity in September in Johnston is 71%.Rainfall
September is the month with the least rainfall in Johnston. Rain falls for 12.2 days and accumulates 1.42" (36mm) of precipitation.Snowfall
In Johnston, snow does not fall in April through November.Daylight
The average length of the day in September is 12h and 22min.On the first day of September in Johnston, sunrise is at 7:01 am and sunset at 7:52 pm. On the last day of the month, sunrise is at 7:21 am and sunset at 7:12 pm EDT.
Sunshine
In September, the average sunshine in Johnston 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 vulnerability from exposure to the Sun's UV radiation for the ordinary person.Note: An average maximum UV index of 6 in September leads to these recommendations:
Stand by precautions and apply sun safety measures. Evading sunburn is of great importance. Avoid direct sunlight between the hours of 10 a.m. and 4 p.m., when UV radiation is at its peak. Keep in mind that shade structures may not provide complete protection. Sunglasses that guard against UVA and UVB rays are pivotal in minimizing sun-induced ocular damage.
Frequently asked questions
How hot does it get in Johnston in September?
What is the average humidity in September in Johnston?
What is the driest month in Johnston?
How much does it rain in Johnston in September?
When it does not snow in Johnston?
How many hours of daylight does Johnston have in September?
What time are sunrise and sunset in September in Johnston?
How long on average sun shines in September in Johnston?
What is the UV index reading in September in Johnston?
Average temperature in September
Johnston, SC
- Average high temperature in September: 84.7°F
The warmest month (with the highest average high temperature) is July (91.4°F).
The month with the lowest average high temperature is January (52.7°F).
- Average low temperature in September: 66.4°F
The month with the highest average low temperature is July (72.5°F).
The coldest month (with the lowest average low temperature) is January (36.9°F).
Average pressure in September
Johnston, SC
- Average pressure in September: 30.02"Hg
The months with the highest atmospheric pressure are January, November and December (30.14"Hg).
The month with the lowest atmospheric pressure is June (29.98"Hg).
Average wind speed in September
Johnston, SC
- Average wind speed in September: 5.8mph
The windiest months (with the highest average wind speed) are February and April (8.1mph).
The calmest month (with the lowest average wind speed) is August (5.2mph).
Average humidity in September
Johnston, SC
- Average humidity in September: 71%
The month with the highest relative humidity is December (76%).
The month with the lowest relative humidity is July (70%).
Average rainfall in September
Johnston, SC
- Average rainfall in September: 1.42"
The wettest month (with the highest rainfall) is December (3.03").
The driest month (with the least rainfall) is September (1.42").
Average rainfall days in September
Johnston, SC
- Average rainfall days in September: 12.2 days
The month with the highest number of rainy days is July (17.5 days).
The month with the least rainy days is November (7.8 days).
Average snowfall in September
Johnston, SC
- Average snowfall in September: 0"
The month with the highest snowfall is February (0.59").
The months with the least snowfall are April, May, June, July, August, September, October and November (0").
Average snowfall days in September
Johnston, SC
- Average snowfall days in September: 0 days
The months with the highest number of snowfall days are January and February (0.4 days).
The months with the least snowfall days are April, May, June, July, August, September and October (0 days).
Average daylight in September /
Average sunshine in September
Johnston, SC
- Average daylight in September: 12h and 2min
The month with the longest days is June (Average daylight: 14h and 24min).
The month with the shortest days is December (Average daylight: 9h and 54min).
- Average sunshine in September: 8h and 4min
The months with the most sunshine are June and July (Average sunshine: 10h and 54min).
The month with the least sunshine is December (Average sunshine: 5h and 24min).
Average sunshine days in September
Johnston, SC
- Average sunshine days in September: 16.2 days
The month with the most sunshine days is October (21.8 days).
The month with the least sunshine days is July (11.2 days).
Average UV index in September
Johnston, SC
- Average UV index in September: 6
The months with the highest UV index are June, July and August (UV index 7).
The month with the lowest UV index is January (UV index 2).
Average cloud cover in September
Johnston, SC
- Average cloud cover in September: 30
The month with the most cloud cover is December (Cloud cover 41).
The month with the least cloud cover is October (Cloud cover 27).
Average visibility in September
Johnston, 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).
Johnston, South Carolina, USA
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