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
The start of September involves a subtle temperature drop, shifting from 81.3°F (27.4°C) in August to a still warm 75.7°F (24.3°C). Saint Marys, in September, experiences an average temperature of 55.9°F (13.3°C) at night.Humidity
In September, the average relative humidity is 76%.Rainfall
In September, the rain falls for 11.1 days. Throughout September, 1.81" (46mm) of precipitation is accumulated. In Saint Marys, during the entire year, the rain falls for 118.9 days and collects up to 18.62" (473mm) of precipitation.Snowfall
June through September are months without snowfall.Daylight
The average length of the day in September is 12h and 28min.On the first day of the month, sunrise is at 6:42 am and sunset at 7:47 pm. On the last day of September, sunrise is at 7:11 am and sunset at 6:57 pm CDT.
Sunshine
The average sunshine in September is 9.3h.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 exposure to the Sun's UV rays for the average person.Note: In September, the maximum UV index of 4 translates into these guidelines:
Ensure safety - Recommendations to avert sunburn are presented. To guard against the harmful effects of the Sun, minimize exposure during midday. Select sunglasses that boast both UVA and UVB protection to limit the adverse effects of the sun on the eyes.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
What is the average September temperature?
What is the average humidity in September?
How many days does it rain in September?
When it does not snow?
Does it snow in Saint Marys in September?
How many hours of daylight does Saint Marys have in September?
When is the sunrise / sunset in September in Saint Marys?
How many hours of sunshine does Saint Marys have in September?
What is the UV index reading in September?
Average temperature in September
Saint Marys, IA
- Average high temperature in September: 75.7°F
The warmest month (with the highest average high temperature) is July (83.1°F).
The month with the lowest average high temperature is January (28.8°F).
- Average low temperature in September: 55.9°F
The month with the highest average low temperature is July (65.7°F).
The coldest month (with the lowest average low temperature) is January (15.3°F).
Average pressure in September
Saint Marys, IA
- Average pressure in September: 30.01"Hg
The month with the highest atmospheric pressure is January (30.16"Hg).
The month with the lowest atmospheric pressure is June (29.89"Hg).
Average wind speed in September
Saint Marys, IA
- Average wind speed in September: 8mph
The windiest month (with the highest average wind speed) is January (10.4mph).
The calmest month (with the lowest average wind speed) is August (6.9mph).
Average humidity in September
Saint Marys, IA
- Average humidity in September: 76%
The months with the highest relative humidity are January and June (82%).
The month with the lowest relative humidity is October (71%).
Average rainfall in September
Saint Marys, IA
- Average rainfall in September: 1.81"
The wettest month (with the highest rainfall) is May (3.07").
The driest month (with the least rainfall) is December (0.55").
Average rainfall days in September
Saint Marys, IA
- Average rainfall days in September: 11.1 days
The months with the highest number of rainy days are May and June (15.9 days).
The month with the least rainy days is January (3.4 days).
Average snowfall in September
Saint Marys, IA
- Average snowfall in September: 0"
The month with the highest snowfall is February (3.03").
The months with the least snowfall are June, July, August and September (0").
Average snowfall days in September
Saint Marys, IA
- Average snowfall days in September: 0 days
The month with the highest number of snowfall days is January (9.7 days).
The months with the least snowfall days are June, July, August and September (0 days).
Average daylight in September /
Average sunshine in September
Saint Marys, IA
- Average daylight in September: 12h and 3min
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: 9h and 2min
The month with the most sunshine is July (Average sunshine: 10h and 24min).
The month with the least sunshine is January (Average sunshine: 4h and 18min).
Average sunshine days in September
Saint Marys, IA
- Average sunshine days in September: 17 days
The month with the most sunshine days is December (21.9 days).
The month with the least sunshine days is June (11 days).
Average UV index in September
Saint Marys, IA
- Average UV index in September: 4
The months with the highest UV index are June, July and August (UV index 6).
The month with the lowest UV index is January (UV index 1).
Average cloud cover in September
Saint Marys, IA
- Average cloud cover in September: 29
The month with the most cloud cover is January (Cloud cover 53).
The month with the least cloud cover is July (Cloud cover 28).
Average visibility in September
Saint Marys, IA
- 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).
Saint Marys, Iowa, USA
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