September weather forecastPrinceton, CA
September
Weather in September
September, the first month of the autumn in Princeton, is still a tropical month, with an average temperature fluctuating between 61°F (16.1°C) and 90.7°F (32.6°C).Temperature
September's arrival aligns with a minor decrease in average high-temperatures, from August's fiery hot 97°F (36.1°C) to a tropical 90.7°F (32.6°C). Despite the stark contrast with daytime temperatures, Princeton's September nights average at a refreshing 61°F (16.1°C).Humidity
September is the least humid month in Princeton, with an average relative humidity of 36%.Rainfall
In Princeton, during September, the rain falls for 1.7 days and regularly aggregates up to 0.08" (2mm) of precipitation. Throughout the year, there are 58.9 rainfall days, and 6.89" (175mm) of precipitation is accumulated.Daylight
In Princeton, the average length of the day in September is 12h and 26min.On the first day of the month, sunrise is at 6:37 am and sunset at 7:38 pm. On the last day of September, sunrise is at 7:03 am and sunset at 6:51 pm PDT.
Sunshine
In September, the average sunshine is 11.2h.UV index
The average daily maximum UV index in September is 6. A UV Index of 6 to 7 symbolizes a high health risk from unprotected exposure to Sun's UV rays for average individuals.Note: In September, the UV index of 6 transforms into the following advice:
Avoid excessive sunlight. Those with lighter skin may experience burning in less than 20 minutes. Remember that the sun's UV radiation is strongest between 10 a.m. and 4 p.m. Make an effort to avoid direct sun exposure during these hours. Sunglasses that guard against UVA and UVB rays are pivotal in minimizing sun-induced ocular damage.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Average temperature in September
Princeton, CA
- Average high temperature in September: 90.7°F
The warmest month (with the highest average high temperature) is July (98.8°F).
The month with the lowest average high temperature is December (54.5°F).
- Average low temperature in September: 61°F
The month with the highest average low temperature is July (61.5°F).
The coldest month (with the lowest average low temperature) is December (42.1°F).
Average pressure in September
Princeton, CA
- Average pressure in September: 29.91"Hg
The month with the highest atmospheric pressure is January (30.15"Hg).
The month with the lowest atmospheric pressure is June (29.9"Hg).
Average wind speed in September
Princeton, CA
- Average wind speed in September: 5.1mph
The windiest month (with the highest average wind speed) is March (6.6mph).
The calmest month (with the lowest average wind speed) is August (5mph).
Average humidity in September
Princeton, CA
- Average humidity in September: 36%
The month with the highest relative humidity is March (71%).
The month with the lowest relative humidity is September (36%).
Average rainfall in September
Princeton, CA
- Average rainfall in September: 0.08"
The wettest months (with the highest rainfall) are February and December (1.3").
The driest months (with the least rainfall) are July and August (0.04").
Average rainfall days in September
Princeton, CA
- Average rainfall days in September: 1.7 days
The month with the highest number of rainy days is March (10.4 days).
The month with the least rainy days is July (1 days).
Average daylight in September /
Average sunshine in September
Princeton, CA
- Average daylight in September: 12h and 24min
The month with the longest days is June (Average daylight: 14h and 54min).
The month with the shortest days is December (Average daylight: 9h and 24min).
- Average sunshine in September: 11h and 12min
The month with the most sunshine is July (Average sunshine: 12h and 6min).
The month with the least sunshine is December (Average sunshine: 5h and 48min).
Average sunshine days in September
Princeton, CA
- Average sunshine days in September: 28 days
The month with the most sunshine days is July (29.8 days).
The month with the least sunshine days is March (19.7 days).
Average UV index in September
Princeton, CA
- Average UV index in September: 6
The months with the highest UV index are June, July and August (UV index 7).
The months with the lowest UV index are February, November and December (UV index 3).
Average cloud cover in September
Princeton, CA
- Average cloud cover in September: 8
The months with the most cloud cover are March and December (Cloud cover 36).
The month with the least cloud cover is July (Cloud cover 4).
Average visibility in September
Princeton, CA
- 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).
