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
September, on average, is the warmest month, registering a high temperature of 70.2°F (21.2°C) and a low of 56.8°F (13.8°C).Humidity
In Hillsborough, California, the average relative humidity in September is 73%.Rainfall
In September, the rain falls for 3.4 days. Throughout September, 0.16" (4mm) of precipitation is accumulated. In Hillsborough, during the entire year, the rain falls for 81.5 days and collects up to 12.8" (325mm) of precipitation.Daylight
In Hillsborough, the average length of the day in September is 12h and 25min.On the first day of September in Hillsborough, sunrise is at 6:40 am and sunset at 7:38 pm. On the last day of the month, sunrise is at 7:04 am and sunset at 6:53 pm PDT.
Sunshine
The average sunshine in September is 10.9h.UV index
June through September, with an average maximum UV index of 5, are months with the highest UV index in Hillsborough. A UV Index reading of 3 to 5 represents a medium health hazard from exposure to the Sun's UV rays for ordinary individuals.Note: The maximum UV index of 5 during September leads to these instructions:
Put precautions into practice - Ensuring skin and eye safety is a necessity. To avoid the Sun's strongest rays, limit exposure around the mid-day period. Wearing a wide-brim hat can block approximately 50% of UV radiation, protecting the eyes.
Frequently asked questions
What time of the year is the hottest in Hillsborough?
What is the temperature in September in Hillsborough?
What is the average humidity in September in Hillsborough?
How much does it rain in Hillsborough in September?
What is the average length of the day in September in Hillsborough?
When is the sunrise / sunset in September in Hillsborough?
How many hours of sunshine does Hillsborough have in September?
What are the months with the highest UV index in Hillsborough?
How high is the UV index in September in Hillsborough?
Average temperature in September
Hillsborough, CA
- Average high temperature in September: 70.2°F
The warmest month (with the highest average high temperature) is September (70.2°F).
The month with the lowest average high temperature is December (55.6°F).
- Average low temperature in September: 56.8°F
The month with the highest average low temperature is September (56.8°F).
The coldest month (with the lowest average low temperature) is January (47.5°F).
Average pressure in September
Hillsborough, 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
Hillsborough, CA
- Average wind speed in September: 6.1mph
The windiest month (with the highest average wind speed) is April (8.3mph).
The calmest month (with the lowest average wind speed) is September (6.1mph).
Average humidity in September
Hillsborough, CA
- Average humidity in September: 73%
The month with the highest relative humidity is August (78%).
The month with the lowest relative humidity is October (70%).
Average rainfall in September
Hillsborough, CA
- Average rainfall in September: 0.16"
The wettest month (with the highest rainfall) is February (2.44").
The driest month (with the least rainfall) is July (0.08").
Average rainfall days in September
Hillsborough, CA
- Average rainfall days in September: 3.4 days
The month with the highest number of rainy days is March (12.8 days).
The months with the least rainy days are June and July (2.4 days).
Average daylight in September /
Average sunshine in September
Hillsborough, 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 48min).
The month with the least sunshine is December (Average sunshine: 5h and 48min).
Average sunshine days in September
Hillsborough, CA
- Average sunshine days in September: 23.2 days
The month with the most sunshine days is July (24.6 days).
The month with the least sunshine days is March (16.3 days).
Average UV index in September
Hillsborough, 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
Hillsborough, CA
- Average cloud cover in September: 15
The month with the most cloud cover is March (Cloud cover 36).
The months with the least cloud cover are July and September (Cloud cover 15).
Average visibility in September
Hillsborough, 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).
Hillsborough, California, USA
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