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
With the onset of September, a modest change to a still warm 82.2°F (27.9°C) from August's 83.5°F (28.6°C) is noted in high-temperature. During September, Fullerton's temperature falls to a steady low-temperature average of 64.8°F (18.2°C).Heat index
The heat index for September is evaluated at 84.2°F (29°C). Uninterrupted activity during exposure could lead to a sense of exhaustion, possibly causing heat cramps.When referencing the heat index, its values are suitable for shady environments and light breezes. With direct sunlight, the heat index could increase by 15 Fahrenheit (8 Celsius) degrees.
Note: The heat index, also known as 'felt air temperature' or 'feels like', embodies the combination of air temperature and moisture content to illustrate perceived heat. This effect is personal, influenced by the individual's physical activity and heat sensitivity, shaped by factors including wind, attire, and metabolic variations. Consider that direct sun exposure can intensify the felt heat, adding potentially 15 Fahrenheit (8 Celsius) degrees to the heat index. Heat index values are particularly meaningful for babies and toddlers. Youngsters are usually more at risk than adults, considering they sweat less. Additionally, their high skin surface area compared to their little bodies and their high heat production due to activity increases their risk.
Humidity
The average relative humidity in September in Fullerton is 58%.Rainfall
In Fullerton, in September, it is raining for 3.5 days, with typically 0.2" (5mm) of accumulated precipitation. Throughout the year, there are 52.5 rainfall days, and 7.09" (180mm) of precipitation is accumulated.Daylight
In Fullerton, the average length of the day in September is 12h and 22min.On the first day of September, sunrise is at 6:26 am and sunset at 7:16 pm. On the last day of the month, sunrise is at 6:45 am and sunset at 6:36 pm PDT.
Sunshine
The average sunshine in September is 10.6h.UV index
June through September, with an average maximum UV index of 6, are months with the highest UV index. A UV Index value of 6 to 7 symbolizes a high threat to health from exposure to the Sun's UV rays for the ordinary person.Note: The daily high UV index of 6 in September translates into this advice:
Fend off overexposure. Sun protection is vital. Avoid direct Sun exposure and stay in the shade between 10 a.m. and 4 p.m., a time when UV radiation is most intense, noting that not all shade structures offer full protection. Your best bet for sun defense on the face, eyes, and neck is a hat with a wide brim.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
What is the temperature in September?
What is the average humidity in September?
How much 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 Fullerton have in September?
What are the months with the highest UV index?
What is the UV index reading in September in Fullerton?
Average temperature in September
Fullerton, CA
- Average high temperature in September: 82.2°F
The warmest month (with the highest average high temperature) is August (83.5°F).
The month with the lowest average high temperature is December (64°F).
- Average low temperature in September: 64.8°F
The month with the highest average low temperature is August (65.5°F).
The coldest month (with the lowest average low temperature) is February (50.2°F).
Average pressure in September
Fullerton, CA
- Average pressure in September: 29.89"Hg
The month with the highest atmospheric pressure is January (30.1"Hg).
The month with the lowest atmospheric pressure is June (29.88"Hg).
Average wind speed in September
Fullerton, CA
- Average wind speed in September: 4.7mph
The windiest month (with the highest average wind speed) is April (6mph).
The calmest months (with the lowest average wind speed) are September and October (4.7mph).
Average humidity in September
Fullerton, CA
- Average humidity in September: 58%
The month with the highest relative humidity is June (65%).
The month with the lowest relative humidity is November (51%).
Average rainfall in September
Fullerton, CA
- Average rainfall in September: 0.2"
The wettest month (with the highest rainfall) is December (1.54").
The driest month (with the least rainfall) is June (0.04").
Average rainfall days in September
Fullerton, CA
- Average rainfall days in September: 3.5 days
The month with the highest number of rainy days is March (7.3 days).
The month with the least rainy days is June (1.5 days).
Average daylight in September /
Average sunshine in September
Fullerton, CA
- Average daylight in September: 12h and 2min
The month with the longest days is June (Average daylight: 14h and 24min).
The month with the shortest days is December (Average daylight: 9h and 54min).
- Average sunshine in September: 10h and 4min
The months with the most sunshine are July and August (Average sunshine: 12h and 0min).
The month with the least sunshine is December (Average sunshine: 6h and 42min).
Average sunshine days in September
Fullerton, CA
- Average sunshine days in September: 23.4 days
The month with the most sunshine days is August (25.8 days).
The month with the least sunshine days is February (20.6 days).
Average UV index in September
Fullerton, CA
- Average UV index in September: 6
The months with the highest UV index are June, July, August and September (UV index 6).
The months with the lowest UV index are January, February, November and December (UV index 4).
Average cloud cover in September
Fullerton, CA
- Average cloud cover in September: 9
The months with the most cloud cover are March and December (Cloud cover 22).
The month with the least cloud cover is August (Cloud cover 5).
Average visibility in September
Fullerton, 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).
Fullerton, California, USA
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