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
South San Francisco experiences its highest temperatures in September, with an average peak of 70°F (21.1°C) and a low of 56.5°F (13.6°C).Humidity
In South San Francisco, the average relative humidity in September is 73%.Rainfall
In South San Francisco, in September, during 1.9 rainfall days, 0.08" (2mm) of precipitation is typically accumulated. Throughout the year, there are 53.6 rainfall days, and 3.9" (99mm) of precipitation is accumulated.Daylight
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 7:38 pm. On the last day of September, sunrise is at 7:05 am and sunset at 6:53 pm PDT.
Sunshine
In South San Francisco, the average sunshine in September is 10.8h.UV index
The months with the highest UV index are June through September, with an average maximum UV index of 5. A UV Index of 3 to 5 symbolizes a moderate health risk from unsafe exposure to UV radiation for average individuals.Note: A maximum daily UV index of 5 during September morphs into the following directions:
Guard yourself - Precautionary measures against sun damage are advocated. Minimize direct exposure to the Sun during midday when its radiation is at its peak. Safeguard your eyes, ears, and face from sun rays with the aid of a wide-brim hat.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
What part of the year is the hottest?
What are September temperatures?
What is the average humidity in September?
How many days does it rain in September?
What is the average length of the day in September?
When is the sunrise / sunset in September?
How many hours of sunshine does South San Francisco have in September?
When is the highest UV index?
What is the UV index intensity in September?
Average temperature in September
South San Francisco, CA
- Average high temperature in September: 70°F
The warmest month (with the highest average high temperature) is September (70°F).
The month with the lowest average high temperature is December (55.6°F).
- Average low temperature in September: 56.5°F
The months with the highest average low temperature are August and September (56.5°F).
The coldest months (with the lowest average low temperature) are January, February and December (47.8°F).
Average pressure in September
South San Francisco, CA
- Average pressure in September: 29.92"Hg
The month with the highest atmospheric pressure is January (30.13"Hg).
The month with the lowest atmospheric pressure is September (29.92"Hg).
Average wind speed in September
South San Francisco, CA
- Average wind speed in September: 6.2mph
The windiest month (with the highest average wind speed) is April (8.5mph).
The calmest month (with the lowest average wind speed) is September (6.2mph).
Average humidity in September
South San Francisco, CA
- Average humidity in September: 73%
The month with the highest relative humidity is August (78%).
The months with the lowest relative humidity are October and November (71%).
Average rainfall in September
South San Francisco, CA
- Average rainfall in September: 0.08"
The wettest month (with the highest rainfall) is February (0.79").
The driest months (with the least rainfall) are June, July and August (0.04").
Average rainfall days in September
South San Francisco, CA
- Average rainfall days in September: 1.9 days
The month with the highest number of rainy days is March (9.4 days).
The month with the least rainy days is June (1.1 days).
Average daylight in September /
Average sunshine in September
South San Francisco, CA
- Average daylight in September: 12h and 2min
The month with the longest days is June (Average daylight: 14h and 42min).
The month with the shortest days is December (Average daylight: 9h and 36min).
- Average sunshine in September: 10h and 5min
The month with the most sunshine is July (Average sunshine: 11h and 42min).
The month with the least sunshine is December (Average sunshine: 5h and 48min).
Average sunshine days in September
South San Francisco, CA
- Average sunshine days in September: 26.3 days
The months with the most sunshine days are June, July and September (26.3 days).
The month with the least sunshine days is March (19.4 days).
Average UV index in September
South San Francisco, CA
- Average UV index in September: 5
The months with the highest UV index are June, July, August and September (UV index 5).
The months with the lowest UV index are February and December (UV index 3).
Average cloud cover in September
South San Francisco, CA
- Average cloud cover in September: 16
The month with the most cloud cover is March (Cloud cover 37).
The month with the least cloud cover is September (Cloud cover 16).
Average visibility in September
South San Francisco, 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).
South San Francisco, California, USA
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