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's average high-temperature is a still warm 82.9°F (28.3°C), maintaining a close comparison with August's 85.3°F (29.6°C). A significant drop from the day's peak to an average low-temperature of 56.5°F (13.6°C) is noted during the nights in September.Heat index
Throughout September, the heat index is calculated to be 84.2°F (29°C). Long-standing exposure and activity could induce a feeling of tiredness and lead to heat cramps.Heat index values are typically calculated for conditions of shade and a light breeze. With direct sunlight, the heat index could increase by 15 Fahrenheit (8 Celsius) degrees.
Note: The heat index, also known as 'real feel' or 'feels like', is a metric representing the sensation of warmth when air temperature and moisture come together. An individual's perception of weather can be influenced by a variety of factors including metabolic differences, being pregnant, and their degree of physical exertion. In the direct sunlight, the weather's impact can be amplified, possibly boosting the heat index by up to 15 Fahrenheit (8 Celsius) degrees. Heat index values are extremely significant for babies and toddlers. Children usually face more risks than adults as their ability to sweat is less. Additionally, their larger skin surface in relation to their petite bodies and higher heat output due to their activities increases their vulnerability.
Humidity
July and September, with an average relative humidity of 55%, are the least humid months in Livermore.Rainfall
In Livermore, during September, the rain falls for 2.3 days and regularly aggregates up to 0.16" (4mm) of precipitation. Throughout the year, there are 70.6 rainfall days, and 11.3" (287mm) of precipitation is accumulated.Daylight
In September, the average length of the day is 12h and 25min.On the first day of the month, sunrise is at 6:37 am and sunset at 7:35 pm. On the last day of September, sunrise is at 7:02 am and sunset at 6:51 pm PDT.
Sunshine
In September, the average sunshine is 11.3h.UV index
In September, the average daily maximum UV index is 5. A UV Index value of 3 to 5 symbolizes a medium vulnerability from unprotected exposure to Sun's UV rays for average individuals.Note: The daily high UV index of 5 during September translates into the following recommendations:
Guard yourself - An obligation to protect skin and eyes from harm exists. Midday is the peak time for the Sun's radiation; stay in the shade and protect yourself. It's wise to wear UVA and UVB-blocking sunglasses when the sun shines brightly.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
How hot does it get in September?
What is the least humid month?
What is the average humidity in September?
How much does it rain in September?
How many hours of daylight does Livermore have in September?
When is the sunrise / sunset in September?
How long on average sun shines in September?
What is the UV index reading in September?
Average temperature in September
Livermore, CA
- Average high temperature in September: 82.9°F
The warmest month (with the highest average high temperature) is July (86°F).
The month with the lowest average high temperature is December (54.9°F).
- Average low temperature in September: 56.5°F
The month with the highest average low temperature is August (56.7°F).
The coldest month (with the lowest average low temperature) is January (41.4°F).
Average pressure in September
Livermore, CA
- Average pressure in September: 29.92"Hg
The month with the highest atmospheric pressure is January (30.14"Hg).
The months with the lowest atmospheric pressure are June, August and September (29.92"Hg).
Average wind speed in September
Livermore, CA
- Average wind speed in September: 5.2mph
The windiest months (with the highest average wind speed) are May and June (6.5mph).
The calmest month (with the lowest average wind speed) is November (4.2mph).
Average humidity in September
Livermore, CA
- Average humidity in September: 55%
The month with the highest relative humidity is March (74%).
The months with the lowest relative humidity are July and September (55%).
Average rainfall in September
Livermore, CA
- Average rainfall in September: 0.16"
The wettest month (with the highest rainfall) is February (2.09").
The driest month (with the least rainfall) is August (0.04").
Average rainfall days in September
Livermore, CA
- Average rainfall days in September: 2.3 days
The month with the highest number of rainy days is March (12.7 days).
The month with the least rainy days is August (1.3 days).
Average daylight in September /
Average sunshine in September
Livermore, 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: 11h and 2min
The month with the most sunshine is July (Average sunshine: 12h and 6min).
The month with the least sunshine is December (Average sunshine: 6h and 0min).
Average sunshine days in September
Livermore, CA
- Average sunshine days in September: 26.5 days
The month with the most sunshine days is August (28.8 days).
The month with the least sunshine days is March (17.6 days).
Average UV index in September
Livermore, CA
- Average UV index in September: 5
The months with the highest UV index are June, July and August (UV index 6).
The months with the lowest UV index are January, February, November and December (UV index 3).
Average cloud cover in September
Livermore, CA
- Average cloud cover in September: 9
The month with the most cloud cover is March (Cloud cover 35).
The month with the least cloud cover is July (Cloud cover 5).
Average visibility in September
Livermore, 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).
Livermore, California, USA
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