September weather forecastDecatur, IN
September
Weather in September
The first month of the autumn, September, is also a moderately hot month in Decatur, Indiana, with an average temperature fluctuating between 55.8°F (13.2°C) and 73.8°F (23.2°C).Temperature
The arrival of September corresponds with a minor reduction in the average high-temperature, down from August's 79.2°F (26.2°C) to a still warm 73.8°F (23.2°C). Decatur records a consistent low-temperature of 55.8°F (13.2°C) during September nights.Humidity
In September, the average relative humidity is 79%.Rainfall
In Decatur, during September, the rain falls for 13.5 days and regularly aggregates up to 1.57" (40mm) of precipitation. Throughout the year, there are 159.4 rainfall days, and 23.74" (603mm) of precipitation is accumulated.Snowfall
In Decatur, snow does not fall in May through September.Daylight
In Decatur, the average length of the day in September is 12h and 27min.On the first day of the month, sunrise is at 7:07 am and sunset at 8:11 pm. On the last day of September, sunrise is at 7:36 am and sunset at 7:22 pm EDT.
Sunshine
In September, the average sunshine is 8h.UV index
The average daily maximum UV index in September is 4. A UV Index estimate of 3 to 5 represents a moderate health risk from unsafe exposure to UV radiation for average individuals.Note: A daily high UV index of 4 in September leads to these guidelines:
Make use of precautions - Suggestions to resist sunburn are communicated. Solar radiation is at its peak intensity during midday, so it's advisable to stay indoors or in the shade. Clothes that are both tight-knit and comfortably loose are prime choices for sun protection.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Average temperature in September
Decatur, IN
- Average high temperature in September: 73.8°F
The warmest month (with the highest average high temperature) is July (81.1°F).
The month with the lowest average high temperature is January (31.3°F).
- Average low temperature in September: 55.8°F
The month with the highest average low temperature is July (64°F).
The coldest month (with the lowest average low temperature) is January (19.8°F).
Average pressure in September
Decatur, IN
- Average pressure in September: 30.04"Hg
The month with the highest atmospheric pressure is November (30.12"Hg).
The month with the lowest atmospheric pressure is June (29.93"Hg).
Average wind speed in September
Decatur, IN
- Average wind speed in September: 6.8mph
The windiest month (with the highest average wind speed) is January (10.6mph).
The calmest month (with the lowest average wind speed) is August (6mph).
Average humidity in September
Decatur, IN
- Average humidity in September: 79%
The months with the highest relative humidity are January and February (83%).
The month with the lowest relative humidity is October (74%).
Average rainfall in September
Decatur, IN
- Average rainfall in September: 1.57"
The wettest month (with the highest rainfall) is May (3.03").
The driest month (with the least rainfall) is February (1.34").
Average rainfall days in September
Decatur, IN
- Average rainfall days in September: 13.5 days
The month with the highest number of rainy days is May (18.3 days).
The month with the least rainy days is February (7.5 days).
Average snowfall in September
Decatur, IN
- Average snowfall in September: 0"
The month with the highest snowfall is February (2.83").
The months with the least snowfall are May, June, July, August and September (0").
Average snowfall days in September
Decatur, IN
- Average snowfall days in September: 0 days
The month with the highest number of snowfall days is January (13.5 days).
The months with the least snowfall days are June, July, August and September (0 days).
Average daylight in September /
Average sunshine in September
Decatur, IN
- Average daylight in September: 12h and 30min
The month with the longest days is June (Average daylight: 15h and 6min).
The month with the shortest days is December (Average daylight: 9h and 18min).
- Average sunshine in September: 8h and 0min
The month with the most sunshine is July (Average sunshine: 10h and 18min).
The month with the least sunshine is January (Average sunshine: 3h and 30min).
Average sunshine days in September
Decatur, IN
- Average sunshine days in September: 14.5 days
The month with the most sunshine days is November (16.3 days).
The month with the least sunshine days is June (10 days).
Average UV index in September
Decatur, IN
- Average UV index in September: 4
The months with the highest UV index are June and July (UV index 6).
The month with the lowest UV index is December (UV index 1).
Average cloud cover in September
Decatur, IN
- Average cloud cover in September: 35
The month with the most cloud cover is January (Cloud cover 64).
The months with the least cloud cover are July and August (Cloud cover 32).
Average visibility in September
Decatur, IN
- Average visibility in September: 6mi
The months with the highest visibility are February, March, April, May, June, July, September, October, November and December (6mi).
The months with the lowest visibility are January and August (5mi).
