September weather forecastRosemont, CA
September
Weather in September
September, the first month of the autumn in Rosemont, is still a tropical month, with an average temperature fluctuating between 88.3°F (31.3°C) and 58.8°F (14.9°C).Temperature
With the arrival of September, Rosemont's average high-temperature registers at a still tropical 88.3°F (31.3°C), indicating a subtle variation from the previous month. Rosemont observes a distinct decrease from peak daytime temperatures, with an average low-temperature of 58.8°F (14.9°C) throughout the month of September.Heat index
For September, the heat index is appraised at a tropical 89.6°F (32°C). Constant exposure and activity lead to possible fatigue. Prolonged exercise may result in heat cramps.For clarity, heat index numbers account for light winds and areas under shade. The presence of direct sunlight can raise the heat index values by up to 15 Fahrenheit (8 Celsius) degrees.
Note: The heat index, also known as 'real feel' or 'apparent temperature', is a composite of temperature and humidity figures to convey how warm it feels. The influence of weather is personal, differing among individuals based on variations in body mass, stature, and the degree of physical exertion. In the direct sunlight, the weather's impact can be amplified, possibly boosting the heat index by up to 15 Fahrenheit (8 Celsius) degrees. Heat index values hold great significance to children. Juveniles often do not understand the need to recuperate and rehydrate. Thirst is a delayed symptom of dehydration - hence, it is vital to maintain hydration, particularly during ongoing physical activities.
Humidity
July and September, with an average relative humidity of 44%, are the least humid months.Rainfall
In Rosemont, in September, it is raining for 2.1 days, with typically 0.16" (4mm) of accumulated precipitation. Throughout the year, there are 70.5 rainfall days, and 15.04" (382mm) of precipitation is accumulated.Daylight
In September, the average length of the day is 12h and 25min.On the first day of the month, sunrise is at 6:35 am and sunset at 7:34 pm. On the last day of September, in Rosemont, sunrise is at 7:01 am and sunset at 6:49 pm PDT.
Sunshine
In September, the average sunshine in Rosemont is 11.2h.UV index
In September, the average daily maximum UV index in Rosemont is 5. A UV Index of 3 to 5 symbolizes a medium health hazard from exposure to the Sun's UV rays for the average person.Note: The average daily UV index of 5 in September transforms into the following instructions:
Ensure safety - Imperative it is to shield skin and eyes from damage. The solar radiation is most powerful near the mid-day, so the exposure to the direct Sun should be reduced accordingly. For excellent sun protection for the eyes, ears, face, and neck, consider a wide-brim hat.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Average temperature in September
Rosemont, CA
- Average high temperature in September: 88.3°F
The warmest month (with the highest average high temperature) is July (94.5°F).
The month with the lowest average high temperature is December (54.3°F).
- Average low temperature in September: 58.8°F
The month with the highest average low temperature is August (59.9°F).
The coldest months (with the lowest average low temperature) are January and December (40.8°F).
Average pressure in September
Rosemont, CA
- Average pressure in September: 29.92"Hg
The month with the highest atmospheric pressure is January (30.15"Hg).
The month with the lowest atmospheric pressure is June (29.9"Hg).
Average wind speed in September
Rosemont, CA
- Average wind speed in September: 4.1mph
The windiest month (with the highest average wind speed) is February (5.7mph).
The calmest month (with the lowest average wind speed) is September (4.1mph).
Average humidity in September
Rosemont, CA
- Average humidity in September: 44%
The month with the highest relative humidity is March (75%).
The months with the lowest relative humidity are July and September (44%).
Average rainfall in September
Rosemont, CA
- Average rainfall in September: 0.16"
The wettest month (with the highest rainfall) is March (2.72").
The driest months (with the least rainfall) are July and August (0.04").
Average rainfall days in September
Rosemont, CA
- Average rainfall days in September: 2.1 days
The month with the highest number of rainy days is March (12.6 days).
The month with the least rainy days is July (1 days).
Average daylight in September /
Average sunshine in September
Rosemont, CA
- Average daylight in September: 12h and 24min
The month with the longest days is June (Average daylight: 14h and 48min).
The month with the shortest days is December (Average daylight: 9h and 30min).
- Average sunshine in September: 11h and 12min
The month with the most sunshine is July (Average sunshine: 12h and 6min).
The month with the least sunshine is December (Average sunshine: 5h and 48min).
Average sunshine days in September
Rosemont, CA
- Average sunshine days in September: 27.5 days
The month with the most sunshine days is July (29.7 days).
The month with the least sunshine days is March (17.6 days).
Average UV index in September
Rosemont, CA
- Average UV index in September: 5
The months with the highest UV index are June and July (UV index 7).
The months with the lowest UV index are January, February, November and December (UV index 3).
Average cloud cover in September
Rosemont, CA
- Average cloud cover in September: 8
The month with the most cloud cover is March (Cloud cover 38).
The month with the least cloud cover is July (Cloud cover 4).
Average visibility in September
Rosemont, 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).
