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 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 shift into September uncovers an average high-temperature of a still warm 77.2°F (25.1°C), subtly different from the previous month. In Petaluma, the nighttime chill during September is a clear shift from the day's highs, with an average of 55.2°F (12.9°C).Humidity
The months with the lowest humidity in Petaluma are September and October, with an average relative humidity of 65%.Rainfall
In Petaluma, in September, during 2.2 rainfall days, 0.08" (2mm) of precipitation is typically accumulated. Throughout the year, in Petaluma, there are 71.1 rainfall days, and 15.24" (387mm) of precipitation is accumulated.Daylight
In Petaluma, the average length of the day in September is 12h and 25min.On the first day of the month, sunrise is at 6:40 am and sunset at 7:39 pm. On the last day of September, sunrise is at 7:06 am and sunset at 6:54 pm PDT.
Sunshine
In Petaluma, the average sunshine in September is 11h.UV index
In Petaluma, the average daily maximum UV index in September is 5. A UV Index of 3 to 5 symbolizes a moderate health risk from exposure to the Sun's UV rays for ordinary individuals.Note: In September, a daily maximum UV index of 5 leads to the following instructions:
Prioritize safety - The need to safeguard skin and eyes from harm is emphasized. Avoiding direct sun during mid-day hours can prevent harmful UV radiation exposure. 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 September temperatures in Petaluma?
What are the least humid months in Petaluma?
What is the average humidity in September in Petaluma?
How much does it rain in Petaluma in September?
What is the average length of the day in September in Petaluma?
What time are sunrise and sunset in September in Petaluma?
How many hours of sunshine does Petaluma have in September?
What is the UV index reading in September in Petaluma?
Average temperature in September
Petaluma, CA
- Average high temperature in September: 77.2°F
The warmest month (with the highest average high temperature) is August (77.9°F).
The month with the lowest average high temperature is December (55.2°F).
- Average low temperature in September: 55.2°F
The month with the highest average low temperature is September (55.2°F).
The coldest month (with the lowest average low temperature) is December (43.2°F).
Average pressure in September
Petaluma, CA
- Average pressure in September: 29.92"Hg
The month with the highest atmospheric pressure is January (30.13"Hg).
The months with the lowest atmospheric pressure are June, August and September (29.92"Hg).
Average wind speed in September
Petaluma, CA
- Average wind speed in September: 5.3mph
The windiest months (with the highest average wind speed) are April and May (7mph).
The calmest month (with the lowest average wind speed) is November (5mph).
Average humidity in September
Petaluma, CA
- Average humidity in September: 65%
The month with the highest relative humidity is March (77%).
The months with the lowest relative humidity are September and October (65%).
Average rainfall in September
Petaluma, CA
- Average rainfall in September: 0.08"
The wettest month (with the highest rainfall) is February (3.5").
The driest months (with the least rainfall) are July and August (0.04").
Average rainfall days in September
Petaluma, CA
- Average rainfall days in September: 2.2 days
The month with the highest number of rainy days is March (12.6 days).
The month with the least rainy days is July (1 days).
Average daylight in September /
Average sunshine in September
Petaluma, CA
- Average daylight in September: 12h and 2min
The month with the longest days is June (Average daylight: 14h and 48min).
The month with the shortest days is December (Average daylight: 9h and 36min).
- Average sunshine in September: 11h and 0min
The month with the most sunshine is July (Average sunshine: 11h and 54min).
The month with the least sunshine is December (Average sunshine: 5h and 42min).
Average sunshine days in September
Petaluma, CA
- Average sunshine days in September: 26.6 days
The month with the most sunshine days is July (28.4 days).
The month with the least sunshine days is March (17.2 days).
Average UV index in September
Petaluma, CA
- Average UV index in September: 5
The month with the highest UV index is June (UV index 6).
The months with the lowest UV index are January, February, November and December (UV index 3).
Average cloud cover in September
Petaluma, CA
- Average cloud cover in September: 11
The month with the most cloud cover is March (Cloud cover 39).
The month with the least cloud cover is July (Cloud cover 10).
Average visibility in September
Petaluma, 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).
Petaluma, California, USA
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