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
The shift into September reveals an average high-temperature of a still moderately hot 81°F (27.2°C), closely mirroring August's climate. In Portola Hills, an average nighttime temperature of 63.7°F (17.6°C) is expected during September.Heat index
September's mean heat index is evaluated at 82.4°F (28°C). Enduring exposure and continuous activity might cause a feeling of tiredness and induce heat cramps.Understand that the heat index values take into account shaded locations and mild winds. Under direct sunshine, the heat index values might be elevated by 15 Fahrenheit (8 Celsius) degrees.
Note: The heat index, also known as 'apparent temperature' or 'real feel', is an indicator that blends the effects of temperature and humidity to depict perceived warmth. The influence of weather is personal, with varied individuals experiencing it differently due to differences in body mass, stature, and physical exertion levels. Given the impact of direct sunlight, it's noteworthy that the felt temperature can rise by 15 Fahrenheit (8 Celsius) degrees. Heat index values are particularly meaningful for babies and toddlers. Children often fail to understand the importance of rest and rehydration. Thirst is a late manifestation of dehydration - hence, it is crucial to stay hydrated, especially during ongoing physical activities.
Humidity
The average relative humidity in September is 61%.Rainfall
In Portola Hills, in September, it is raining for 4.6 days, with typically 0.31" (8mm) of accumulated precipitation. Throughout the year, there are 65.4 rainfall days, and 9.17" (233mm) of precipitation is accumulated.Daylight
In September, the average length of the day is 12h and 22min.On the first day of the month, sunrise is at 6:24 am and sunset at 7:15 pm. On the last day of September, in Portola Hills, sunrise is at 6:44 am and sunset at 6:35 pm PDT.
Sunshine
In Portola Hills, 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 in Portola Hills. A UV Index estimate of 6 to 7 represents a high health hazard from unsafe exposure to UV radiation for the average person.Note: The maximum UV index of 6 during September leads to these instructions:
Guard against overexposure. Protection from sun-induced harm is essential. The Sun's UV radiation is most potent between 10 a.m. and 4 p.m. Try to limit direct exposure to the Sun during this period. Experience reduced UV exposure by about half when donning a wide-brim hat.
Frequently asked questions
What is the average September temperature in Portola Hills?
What is the average humidity in September in Portola Hills?
How much does it rain in Portola Hills in September?
How many hours of daylight does Portola Hills have in September?
When are sunrise and sunset in September in Portola Hills?
How long on average sun shines in September in Portola Hills?
What is the month with the highest UV index in Portola Hills?
How high is the UV index in September in Portola Hills?
Average temperature in September
Portola Hills, CA
- Average high temperature in September: 81°F
The warmest month (with the highest average high temperature) is August (82°F).
The month with the lowest average high temperature is December (63.1°F).
- Average low temperature in September: 63.7°F
The month with the highest average low temperature is August (64.4°F).
The coldest month (with the lowest average low temperature) is February (48.7°F).
Average pressure in September
Portola Hills, CA
- Average pressure in September: 29.88"Hg
The month with the highest atmospheric pressure is January (30.1"Hg).
The months with the lowest atmospheric pressure are June and September (29.88"Hg).
Average wind speed in September
Portola Hills, CA
- Average wind speed in September: 4.5mph
The windiest months (with the highest average wind speed) are April and May (5.7mph).
The calmest months (with the lowest average wind speed) are August and September (4.5mph).
Average humidity in September
Portola Hills, CA
- Average humidity in September: 61%
The months with the highest relative humidity are May and June (69%).
The month with the lowest relative humidity is November (55%).
Average rainfall in September
Portola Hills, CA
- Average rainfall in September: 0.31"
The wettest month (with the highest rainfall) is December (1.85").
The driest month (with the least rainfall) is June (0.08").
Average rainfall days in September
Portola Hills, CA
- Average rainfall days in September: 4.6 days
The month with the highest number of rainy days is March (8.1 days).
The month with the least rainy days is June (2 days).
Average daylight in September /
Average sunshine in September
Portola Hills, 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: 10h and 0min).
- 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 36min).
Average sunshine days in September
Portola Hills, CA
- Average sunshine days in September: 21.8 days
The months with the most sunshine days are January and October (24.2 days).
The month with the least sunshine days is May (19.3 days).
Average UV index in September
Portola Hills, 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, March, November and December (UV index 4).
Average cloud cover in September
Portola Hills, CA
- Average cloud cover in September: 10
The months with the most cloud cover are March and December (Cloud cover 24).
The month with the least cloud cover is August (Cloud cover 6).
Average visibility in September
Portola Hills, 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).
Portola Hills, California, USA
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