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 transition to September results in a modest reduction in average high-temperature, moving from a warm 80.1°F (26.7°C) in August to a still moderately hot 74.1°F (23.4°C). September nights are marked by an average temperature drop to a cool 55°F (12.8°C).Humidity
In September, the average relative humidity is 77%.Rainfall
In Princeton, in September, during 11.5 rainfall days, 2.36" (60mm) of precipitation is typically accumulated. In Princeton, during the entire year, the rain falls for 146.6 days and collects up to 28.86" (733mm) of precipitation.Snowfall
May through September are months without snowfall.Daylight
In Princeton, the average length of the day in September is 12h and 28min.On the first day of the month, sunrise is at 6:28 am and sunset at 7:34 pm. On the last day of September, sunrise is at 6:57 am and sunset at 6:44 pm CDT.
Sunshine
The average sunshine in September is 9.2h.UV index
The average daily maximum UV index in September in Princeton is 4. A UV Index value of 3 to 5 symbolizes a moderate threat to health from exposure to the Sun's UV rays for the ordinary person.Note: A daily maximum UV index of 4 in September translates into the following instructions:
Adopt protective measures - Requirement to safeguard skin and eyes from harm exists. Limiting exposure to the direct Sun during midday hours can help prevent harmful UV radiation effects. A wide-brim hat offers excellent sun protection for the eyes, ears, face, and neck. Sunglasses with UVA and UVB protection significantly reduce eye damage from sun exposure.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
What is the temperature in September?
What is the average humidity in September?
How much does it rain in Princeton in September?
When it does not snow?
Does it snow in September?
What is the average length of the day in September?
What time are sunrise and sunset in September?
How many hours of sunshine does Princeton have in September?
What is the UV index intensity in September?
Average temperature in September
Princeton, IA
- Average high temperature in September: 74.1°F
The warmest month (with the highest average high temperature) is July (80.4°F).
The month with the lowest average high temperature is January (26.8°F).
- Average low temperature in September: 55°F
The month with the highest average low temperature is July (64.2°F).
The coldest month (with the lowest average low temperature) is January (14.4°F).
Average pressure in September
Princeton, IA
- Average pressure in September: 30.02"Hg
The month with the highest atmospheric pressure is January (30.13"Hg).
The month with the lowest atmospheric pressure is June (29.91"Hg).
Average wind speed in September
Princeton, IA
- Average wind speed in September: 7.6mph
The windiest month (with the highest average wind speed) is April (10.4mph).
The calmest months (with the lowest average wind speed) are July and August (6.6mph).
Average humidity in September
Princeton, IA
- Average humidity in September: 77%
The month with the highest relative humidity is January (85%).
The month with the lowest relative humidity is October (73%).
Average rainfall in September
Princeton, IA
- Average rainfall in September: 2.36"
The wettest month (with the highest rainfall) is May (4.45").
The driest months (with the least rainfall) are January and February (1.34").
Average rainfall days in September
Princeton, IA
- Average rainfall days in September: 11.5 days
The month with the highest number of rainy days is May (18 days).
The month with the least rainy days is February (5.5 days).
Average snowfall in September
Princeton, IA
- Average snowfall in September: 0"
The month with the highest snowfall is January (4.8").
The months with the least snowfall are May, June, July, August and September (0").
Average snowfall days in September
Princeton, IA
- Average snowfall days in September: 0 days
The month with the highest number of snowfall days is January (12.3 days).
The months with the least snowfall days are May, June, July, August and September (0 days).
Average daylight in September /
Average sunshine in September
Princeton, IA
- Average daylight in September: 12h and 3min
The month with the longest days is June (Average daylight: 15h and 12min).
The month with the shortest days is December (Average daylight: 9h and 12min).
- Average sunshine in September: 9h and 1min
The month with the most sunshine is August (Average sunshine: 10h and 0min).
The month with the least sunshine is January (Average sunshine: 4h and 0min).
Average sunshine days in September
Princeton, IA
- Average sunshine days in September: 16.4 days
The month with the most sunshine days is November (18 days).
The month with the least sunshine days is June (10.3 days).
Average UV index in September
Princeton, IA
- 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 January (UV index 1).
Average cloud cover in September
Princeton, IA
- Average cloud cover in September: 30
The month with the most cloud cover is January (Cloud cover 58).
The months with the least cloud cover are August and September (Cloud cover 30).
Average visibility in September
Princeton, IA
- Average visibility in September: 6mi
The months with the highest visibility are February, March, April, May, June, August, September, October, November and December (6mi).
The months with the lowest visibility are January and July (5mi).
Princeton, Iowa, USA
Weather forecast for your location
2. Allow the app to use your location