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
In Princeton, the average high-temperature in September slightly decreases from a moderately hot 78.4°F (25.8°C) in August to a pleasant 71.1°F (21.7°C). Princeton sees an average low-temperature of 52.7°F (11.5°C) during September.Humidity
In Princeton, the average relative humidity in September is 79%.Rainfall
In Princeton, in September, it is raining for 11.3 days, with typically 0.79" (20mm) of accumulated precipitation. Throughout the year, there are 119.4 rainfall days, and 12.44" (316mm) of precipitation is accumulated.Snowfall
In Princeton, snow does not fall in June through September.Daylight
The average length of the day in September is 12h and 29min.On the first day of the month, sunrise is at 6:13 am and sunset at 7:21 pm. On the last day of September, sunrise is at 6:44 am and sunset at 6:30 pm EDT.
Sunshine
The average sunshine in September is 7.9h.UV index
In Princeton, the average daily maximum UV index in September is 4. A UV Index estimate of 3 to 5 represents a moderate threat to health from exposure to the Sun's UV rays for ordinary individuals.Note: In September, the maximum UV index of 4 suggests this advice:
Take measures. Individuals with light skin might experience burns in under 30 minutes. Midday is when the Sun's radiation is strongest; avoid prolonged exposure during this time. To mitigate harm from sun exposure, pick sunglasses offering UVA and UVB defense.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
What are the temperatures in September?
What is the average humidity in September?
How many days does it rain 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?
How high is the UV index in September?
Average temperature in September
Princeton, MA
- Average high temperature in September: 71.1°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 (29.7°F).
- Average low temperature in September: 52.7°F
The month with the highest average low temperature is July (61.3°F).
The coldest month (with the lowest average low temperature) is January (17.6°F).
Average pressure in September
Princeton, MA
- Average pressure in September: 30.06"Hg
The month with the highest atmospheric pressure is November (30.07"Hg).
The month with the lowest atmospheric pressure is June (29.92"Hg).
Average wind speed in September
Princeton, MA
- Average wind speed in September: 6mph
The windiest month (with the highest average wind speed) is January (8.8mph).
The calmest month (with the lowest average wind speed) is August (5.5mph).
Average humidity in September
Princeton, MA
- Average humidity in September: 79%
The month with the highest relative humidity is February (82%).
The month with the lowest relative humidity is April (73%).
Average rainfall in September
Princeton, MA
- Average rainfall in September: 0.79"
The wettest months (with the highest rainfall) are June and July (1.3").
The driest month (with the least rainfall) is February (0.71").
Average rainfall days in September
Princeton, MA
- Average rainfall days in September: 11.3 days
The month with the highest number of rainy days is July (14 days).
The month with the least rainy days is February (4.4 days).
Average snowfall in September
Princeton, MA
- Average snowfall in September: 0"
The month with the highest snowfall is March (2.87").
The months with the least snowfall are June, July, August and September (0").
Average snowfall days in September
Princeton, MA
- Average snowfall days in September: 0 days
The month with the highest number of snowfall days is January (9.2 days).
The months with the least snowfall days are June, July, August and September (0 days).
Average daylight in September /
Average sunshine in September
Princeton, MA
- 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 6min).
- Average sunshine in September: 7h and 5min
The months with the most sunshine are July and August (Average sunshine: 9h and 48min).
The month with the least sunshine is February (Average sunshine: 4h and 12min).
Average sunshine days in September
Princeton, MA
- Average sunshine days in September: 17 days
The month with the most sunshine days is January (19.6 days).
The month with the least sunshine days is April (14.3 days).
Average UV index in September
Princeton, MA
- Average UV index in September: 4
The month with the highest UV index is July (UV index 6).
The months with the lowest UV index are January, February, March, October, November and December (UV index 2).
Average cloud cover in September
Princeton, MA
- Average cloud cover in September: 42
The month with the most cloud cover is March (Cloud cover 53).
The month with the least cloud cover is August (Cloud cover 38).
Average visibility in September
Princeton, MA
- Average visibility in September: 5mi
The months with the highest visibility are April, November and December (6mi).
The months with the lowest visibility are January, February, March, May, June, July, August, September and October (5mi).
Princeton, Massachusetts, USA
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