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
San Dimas's transition from August to September introduces an average high-temperature of a still tropical 86.7°F (30.4°C), marking an insignificant variation from the 89.4°F (31.9°C). September presents a sharp fall from San Dimas's daytime highs to an average low-temperature of 63.3°F (17.4°C).Heat index
September's heat index is calculated to be a tropical 87.8°F (31°C). Extended exposure and activity might lead to tiredness, potentially resulting in heat cramps.When referencing the heat index, its values are suitable for shady environments and light breezes. With exposure to direct sunshine, the heat index could climb by 15 Fahrenheit (8 Celsius) degrees.
Note: The heat index, also known as 'felt air temperature' or 'apparent temperature', joins air temperature with relative humidity to produce a temperature perception for humans. The effect is personal, with varied weather perceptions among individuals due to differences in body mass, stature, and physical activity. Remember, direct sunlight exposure can heighten the heat impact and might increase the heat index by 15 Fahrenheit (8 Celsius) degrees. Heat index values are of high significance for children. Youngsters typically face more danger than adults since they sweat less. Their larger skin surface compared to their small bodies and heightened heat production from their activities augment their vulnerability.
Humidity
In September, the average relative humidity is 46%.Rainfall
In San Dimas, during September, the rain falls for 2.5 days and regularly aggregates up to 0.12" (3mm) of precipitation. In San Dimas, during the entire year, the rain falls for 45.2 days and collects up to 6.5" (165mm) of precipitation.Daylight
In September, the average length of the day is 12h and 22min.On the first day of September, sunrise is at 6:25 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
In San Dimas, the average sunshine in September is 10.7h.UV index
In San Dimas, the average daily maximum UV index in September is 6. A UV Index of 6 to 7 symbolizes a high health vulnerability from unprotected exposure to Sun's UV rays for the ordinary person.Note: The maximum daily UV index, 6 in September, converts into the following recommendations:
Guard oneself from overexposure. Defence against sun injury is vital. It's important to stay in the shade and limit exposure to the sun from 10 a.m. to 4 p.m., when UV radiation is most intense, although remember that shade structures may not provide full sun protection. Loose clothes with a tight weave are optimal for safeguarding yourself against the Sun's rays.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
How hot is it in September?
What is the average humidity in September in San Dimas?
How many days does it rain in September in San Dimas?
What is the average length of the day in September?
When are sunrise and sunset in September?
How long on average sun shines in September?
What is the UV index intensity in September?
Average temperature in September
San Dimas, CA
- Average high temperature in September: 86.7°F
The warmest month (with the highest average high temperature) is August (89.4°F).
The month with the lowest average high temperature is December (62.4°F).
- Average low temperature in September: 63.3°F
The month with the highest average low temperature is August (64.9°F).
The coldest month (with the lowest average low temperature) is December (45.5°F).
Average pressure in September
San Dimas, CA
- Average pressure in September: 29.88"Hg
The month with the highest atmospheric pressure is January (30.1"Hg).
The month with the lowest atmospheric pressure is June (29.87"Hg).
Average wind speed in September
San Dimas, CA
- Average wind speed in September: 4.3mph
The windiest months (with the highest average wind speed) are April and May (5.7mph).
The calmest month (with the lowest average wind speed) is September (4.3mph).
Average humidity in September
San Dimas, CA
- Average humidity in September: 46%
The months with the highest relative humidity are March and May (55%).
The months with the lowest relative humidity are August and November (45%).
Average rainfall in September
San Dimas, CA
- Average rainfall in September: 0.12"
The wettest month (with the highest rainfall) is February (1.46").
The driest month (with the least rainfall) is June (0.04").
Average rainfall days in September
San Dimas, CA
- Average rainfall days in September: 2.5 days
The month with the highest number of rainy days is March (6.3 days).
The month with the least rainy days is June (1.2 days).
Average daylight in September /
Average sunshine in September
San Dimas, 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 June and July (Average sunshine: 12h and 6min).
The months with the least sunshine are January, February and December (Average sunshine: 7h and 0min).
Average sunshine days in September
San Dimas, CA
- Average sunshine days in September: 25.5 days
The month with the most sunshine days is June (27.8 days).
The month with the least sunshine days is February (22 days).
Average UV index in September
San Dimas, CA
- Average UV index in September: 6
The months with the highest UV index are July and August (UV index 7).
The month with the lowest UV index is December (UV index 3).
Average cloud cover in September
San Dimas, CA
- Average cloud cover in September: 6
The months with the most cloud cover are March and December (Cloud cover 21).
The month with the least cloud cover is August (Cloud cover 5).
Average visibility in September
San Dimas, 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).
San Dimas, California, USA
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