September weather forecastSylmar, CA
September
Weather in September
September, the first month of the autumn in Sylmar, is still a warm month, with an average temperature fluctuating between 83.1°F (28.4°C) and 62.6°F (17°C).Temperature
September's average high-temperature is a still moderately hot 83.1°F (28.4°C), maintaining a close comparison with August's 85.8°F (29.9°C). Throughout the nights in September, an average low-temperature of 62.6°F (17°C) is noted.Heat index
September's average heat index is computed to be 84.2°F (29°C). Constant exposure and activity lead to possible fatigue. Prolonged exercise may result in heat cramps.Take into consideration that the heat index values are calculated for shade and light wind conditions. Direct sunshine exposure could raise heat index values by as much as 15 Fahrenheit (8 Celsius) degrees.
Note: The heat index, also known as 'feels like' or 'felt air temperature', ties air temperature with relative humidity to produce the perceived temperature sensation. This effect is personal, influenced by the individual's physical activity and heat sensitivity, shaped by factors including wind, attire, and metabolic variations. Direct sun rays can make one feel hotter, potentially raising the heat index by 15 Fahrenheit (8 Celsius) degrees. Heat index values are particularly relevant to children. Young ones are generally more prone to risk than adults due to their reduced ability to sweat. Their large skin surface area relative to their diminutive bodies and elevated heat production from their activities further enhance this risk.
Humidity
In September, the average relative humidity is 51%.Rainfall
In Sylmar, in September, it is raining for 2.6 days, with typically 0.12" (3mm) of accumulated precipitation. Throughout the year, there are 39.8 rainfall days, and 7.52" (191mm) of precipitation is accumulated.Daylight
The average length of the day in September is 12h and 22min.On the first day of the month, sunrise is at 6:27 am and sunset at 7:19 pm. On the last day of September, sunrise is at 6:48 am and sunset at 6:38 pm PDT.
Sunshine
In September, the average sunshine is 10.8h.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 health hazard from exposure to the Sun's UV rays for the ordinary person.Note: The maximum daily UV index of 6 during September translates into the following directions:
Ward off overexposure. Defence against solar harm is crucial. Limit your direct sun exposure, especially between 10 a.m. and 4 p.m., when UV radiation is strongest. Shade structures might not provide complete sun protection. A wide-brim hat offers excellent sun protection for the eyes, ears, face, and neck. Sunglasses with UVA and UVB protection significantly reduce eye damage from sun exposure.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Average temperature in September
Sylmar, CA
- Average high temperature in September: 83.1°F
The warmest month (with the highest average high temperature) is August (85.8°F).
The month with the lowest average high temperature is December (61.7°F).
- Average low temperature in September: 62.6°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 (46.2°F).
Average pressure in September
Sylmar, CA
- Average pressure in September: 29.9"Hg
The month with the highest atmospheric pressure is January (30.11"Hg).
The month with the lowest atmospheric pressure is June (29.89"Hg).
Average wind speed in September
Sylmar, CA
- Average wind speed in September: 4.5mph
The windiest months (with the highest average wind speed) are January and December (6.2mph).
The calmest month (with the lowest average wind speed) is September (4.5mph).
Average humidity in September
Sylmar, CA
- Average humidity in September: 51%
The month with the highest relative humidity is June (58%).
The month with the lowest relative humidity is November (47%).
Average rainfall in September
Sylmar, CA
- Average rainfall in September: 0.12"
The wettest month (with the highest rainfall) is February (1.54").
The driest month (with the least rainfall) is June (0").
Average rainfall days in September
Sylmar, CA
- Average rainfall days in September: 2.6 days
The month with the highest number of rainy days is March (6.3 days).
The month with the least rainy days is June (0.8 days).
Average daylight in September /
Average sunshine in September
Sylmar, CA
- Average daylight in September: 12h and 24min
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 48min
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: 6h and 48min).
Average sunshine days in September
Sylmar, CA
- Average sunshine days in September: 26.7 days
The month with the most sunshine days is May (28.8 days).
The month with the least sunshine days is February (22.9 days).
Average UV index in September
Sylmar, CA
- Average UV index in September: 6
The months with the highest UV index are June, July, August and September (UV index 6).
The month with the lowest UV index is December (UV index 3).
Average cloud cover in September
Sylmar, CA
- Average cloud cover in September: 7
The month with the most cloud cover is March (Cloud cover 22).
The month with the least cloud cover is August (Cloud cover 4).
Average visibility in September
Sylmar, 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).
