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
During September, the average high-temperature is a still moderately hot 82.9°F (28.3°C), maintaining a close resemblance to that of the preceding month. September nights are characterized by a significant departure from the daytime highs, dropping to an average temperature of 56.5°F (13.6°C).Heat index
In September, the heat index is appraised at 84.2°F (29°C). Exhaustion might be the outcome of enduring exposure and continuous activity, with a risk of heat cramps.When considering the heat index, it's pivotal to note it is for shade and mild wind conditions. Exposure to the sun directly might heighten the heat index by 15 Fahrenheit (8 Celsius) degrees.
Note: The heat index, also known as 'apparent temperature' or 'felt air temperature', is a metric representing the sensation of warmth when air temperature and moisture come together. This effect is subjective, differing among individuals based on their physical activity and perception of heat, which can be influenced by factors like wind, clothing, and metabolic variances. It is essential to be conscious of the fact that direct sunlight can intensify the felt heat, leading to an elevation in the heat index by 15 Fahrenheit (8 Celsius) degrees. Heat index values are highly critical for babies and toddlers. Young people are generally more susceptible than adults because they perspire less. Furthermore, their proportionally larger skin surface to their petite bodies and the increased heat output from their actions add to the risk.
Humidity
The months with the lowest humidity are July and September, with an average relative humidity of 55%.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, in Livermore, there are 70.6 rainfall days, and 11.3" (287mm) of precipitation is accumulated.Daylight
In Livermore, the average length of the day in September is 12h and 25min.On the first day of September in Livermore, California, sunrise is at 6:37 am and sunset at 7:35 pm. On the last day of the month, sunrise is at 7:02 am and sunset at 6:51 pm PDT.
Sunshine
In Livermore, the average sunshine in September is 11.3h.UV index
In Livermore, 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 the average person.Note: The UV index of 5 during September translates into the following guidance:
Ensure safety - Sun damage prevention is strongly urged. Solar radiation peaks around mid-day, so it's wise to limit exposure to the Sun at this time. During bright days, sunglasses that offer UVA and UVB defense are recommended.
Frequently asked questions
How hot is it in Livermore in September?
What are the least humid months in Livermore?
What is the average humidity in September in Livermore?
How many days does it rain in September in Livermore?
What is the average length of the day in September in Livermore?
What time are sunrise and sunset in September in Livermore?
How long on average sun shines in September in Livermore?
How high is the UV index in September in Livermore?
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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