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
September's arrival subtly correlates with a reduction in the average high-temperature, down from a hot 88.3°F (31.3°C) in August to a moderately hot 81.9°F (27.7°C). In September, the average low-temperature is an enjoyable 60.8°F (16°C).Heat index
The heat index value for September is appraised at a hot 86°F (30°C). Ongoing activity coupled with exposure often results in weariness and could induce heat cramps.Be aware that heat index ratings are designed for shaded locations and minor breezes. Exposure to unobstructed sunshine could lead to an increase in the heat index by 15 Fahrenheit (8 Celsius) degrees.
Note: The heat index, also known as 'feels like' or 'apparent temperature', blends air temperature and moisture content to represent the felt temperature to humans. This effect is personal, influenced by the individual's physical activity and heat sensitivity, shaped by factors including wind, attire, and metabolic variations. One should be aware that direct sunshine can amplify the perceived temperature, raising the heat index by as much as 15 Fahrenheit (8 Celsius) degrees. Heat index values are primarily vital for children. Youngsters frequently overlook the need for breaks and fluid intake. Thirst is an advanced sign of dehydration - thereby highlighting the importance of keeping hydrated, particularly during long physical activities.
Humidity
In Alton, the average relative humidity in September is 73%.Rainfall
September is the month with the least rainfall. Rain falls for 12 days and accumulates 1.57" (40mm) of precipitation.Snowfall
May through October are months without snowfall.Daylight
In September, the average length of the day in Alton is 12h and 24min.On the first day of the month, sunrise is at 6:37 am and sunset at 7:33 pm. On the last day of September, sunrise is at 7:00 am and sunset at 6:50 pm CDT.
Sunshine
In Alton, the average sunshine in September is 9.4h.UV index
In September, the average daily maximum UV index in Alton is 5. A UV Index estimate of 3 to 5 represents a medium vulnerability from exposure to the Sun's UV radiation for the average person.Note: During September, 5 as the daily maximum UV index converts into the following advice:
Preventative actions are necessary - Suggestions to safeguard against sun damage are in order. The Sun's most intense and consequently most harmful UV radiation during midday hours should be decreased by minimizing exposure and seeking shade. Clothes that are both tight-knit and comfortably loose are prime choices for sun protection.
Frequently asked questions
What are the temperatures in Alton in September?
What is the average humidity in September in Alton?
What is the driest month in Alton?
How many days does it rain in September in Alton?
When it does not snow in Alton?
What is the average length of the day in September in Alton?
When are sunrise and sunset in September in Alton?
How long on average sun shines in September in Alton?
What is the UV index intensity in September in Alton?
Average temperature in September
Alton, MO
- Average high temperature in September: 81.9°F
The warmest month (with the highest average high temperature) is July (89.4°F).
The month with the lowest average high temperature is January (43.3°F).
- Average low temperature in September: 60.8°F
The month with the highest average low temperature is July (68.5°F).
The coldest month (with the lowest average low temperature) is January (28.4°F).
Average pressure in September
Alton, MO
- Average pressure in September: 30.02"Hg
The month with the highest atmospheric pressure is January (30.16"Hg).
The month with the lowest atmospheric pressure is June (29.93"Hg).
Average wind speed in September
Alton, MO
- Average wind speed in September: 5.7mph
The windiest months (with the highest average wind speed) are January, February, March and April (8.1mph).
The calmest months (with the lowest average wind speed) are July and August (5.3mph).
Average humidity in September
Alton, MO
- Average humidity in September: 73%
The months with the highest relative humidity are March and May (79%).
The month with the lowest relative humidity is October (72%).
Average rainfall in September
Alton, MO
- Average rainfall in September: 1.57"
The wettest month (with the highest rainfall) is May (4.25").
The driest month (with the least rainfall) is September (1.57").
Average rainfall days in September
Alton, MO
- Average rainfall days in September: 12 days
The month with the highest number of rainy days is May (16.5 days).
The month with the least rainy days is January (8.6 days).
Average snowfall in September
Alton, MO
- Average snowfall in September: 0"
The month with the highest snowfall is February (1.26").
The months with the least snowfall are May, June, July, August, September and October (0").
Average snowfall days in September
Alton, MO
- Average snowfall days in September: 0 days
The month with the highest number of snowfall days is February (2.8 days).
The months with the least snowfall days are May, June, July, August, September and October (0 days).
Average daylight in September /
Average sunshine in September
Alton, MO
- Average daylight in September: 12h and 2min
The month with the longest days is June (Average daylight: 14h and 36min).
The month with the shortest days is December (Average daylight: 9h and 42min).
- Average sunshine in September: 9h and 2min
The month with the most sunshine is June (Average sunshine: 10h and 24min).
The month with the least sunshine is February (Average sunshine: 4h and 48min).
Average sunshine days in September
Alton, MO
- Average sunshine days in September: 16.5 days
The month with the most sunshine days is December (19.6 days).
The month with the least sunshine days is May (12.3 days).
Average UV index in September
Alton, MO
- Average UV index in September: 5
The month with the highest UV index is June (UV index 7).
The months with the lowest UV index are January and December (UV index 2).
Average cloud cover in September
Alton, MO
- Average cloud cover in September: 31
The month with the most cloud cover is March (Cloud cover 49).
The month with the least cloud cover is June (Cloud cover 29).
Average visibility in September
Alton, MO
- Average visibility in September: 6mi
The months with the highest visibility are January, February, March, April, June, August, September, October, November and December (6mi).
The months with the lowest visibility are May and July (5mi).
Alton, Missouri, USA
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