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 arrival registers an average high-temperature of a still hot 88.3°F (31.3°C), closely aligning with the temperature of the previous month. Alta Loma in September observes a sharp transition from the daytime heat, falling to an average low of 63.9°F (17.7°C).Heat index
September's mean heat index is computed to be a tropical 89.6°F (32°C). If activity and exposure persist, they could induce fatigue, leading to possible heat cramps.Research indicates the heat index considers values in shaded locales and with light winds. Direct sunshine exposure could raise heat index values by as much as 15 Fahrenheit (8 Celsius) degrees.
Note: The heat index, also known as 'apparent temperature' or 'feels like', unifies temperature and humidity readings to offer a comprehensive feel of warmth. Elements of metabolic variation, physical activity, and clothing contribute to the effect of temperature on an individual. Exposure to direct sun rays can influence the heat you feel, pushing the heat index up by 15 Fahrenheit (8 Celsius) degrees. Heat index values are especially vital to children. Younglings are generally more in peril than adults due to their reduced perspiration. Coupled with a larger skin surface relative to their tiny bodies and greater heat production because of their activity, they become more at risk.
Humidity
The average relative humidity in September is 43%.Rainfall
In Alta Loma, during September, the rain falls for 2.3 days and regularly aggregates up to 0.12" (3mm) of precipitation. Throughout the year, there are 50.5 rainfall days, and 7.56" (192mm) of precipitation is accumulated.Daylight
The average length of the day in September in Alta Loma is 12h and 22min.On the first day of September, sunrise is at 6:24 am and sunset at 7:15 pm. On the last day of the month, sunrise is at 6:44 am and sunset at 6:35 pm PDT.
Sunshine
The average sunshine in September is 10.7h.UV index
In September, the average daily maximum UV index is 6. A UV Index of 6 to 7 symbolizes a high threat to health from exposure to the Sun's UV radiation for the average person.Note: In September, a daily maximum UV index of 6 leads to the following instructions:
Guard oneself from overexposure. Defence against sun injury is vital. Try to minimize direct Sun exposure between 10 a.m. and 4 p.m., the peak period for UV radiation. Also note that objects like parasols or canopies might not provide complete sun protection. Sun protection is enhanced with clothing that boasts a tight weave yet offers a loose fit.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Is it hot during September?
What is the average humidity in September?
How many days does it rain in September?
What is the average length of the day in September?
When are sunrise and sunset in September?
How many hours of sunshine does Alta Loma have in September?
How high is the UV index in September?
Average temperature in September
Alta Loma, CA
- Average high temperature in September: 88.3°F
The warmest month (with the highest average high temperature) is August (91.2°F).
The month with the lowest average high temperature is December (61.3°F).
- Average low temperature in September: 63.9°F
The month with the highest average low temperature is August (66.7°F).
The coldest month (with the lowest average low temperature) is February (45.1°F).
Average pressure in September
Alta Loma, 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 (29.86"Hg).
Average wind speed in September
Alta Loma, CA
- Average wind speed in September: 4.5mph
The windiest months (with the highest average wind speed) are April and May (5.9mph).
The calmest month (with the lowest average wind speed) is September (4.5mph).
Average humidity in September
Alta Loma, CA
- Average humidity in September: 43%
The months with the highest relative humidity are February, March and May (53%).
The month with the lowest relative humidity is August (41%).
Average rainfall in September
Alta Loma, CA
- Average rainfall in September: 0.12"
The wettest month (with the highest rainfall) is February (1.73").
The driest month (with the least rainfall) is June (0.04").
Average rainfall days in September
Alta Loma, CA
- Average rainfall days in September: 2.3 days
The month with the highest number of rainy days is March (7.5 days).
The month with the least rainy days is June (1.2 days).
Average daylight in September /
Average sunshine in September
Alta Loma, 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 month with the most sunshine is July (Average sunshine: 12h and 6min).
The month with the least sunshine is February (Average sunshine: 6h and 54min).
Average sunshine days in September
Alta Loma, CA
- Average sunshine days in September: 25.7 days
The month with the most sunshine days is June (27.7 days).
The month with the least sunshine days is February (21.4 days).
Average UV index in September
Alta Loma, 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
Alta Loma, 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 4).
Average visibility in September
Alta Loma, 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).
Alta Loma, California, USA
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