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 uncovers an average high-temperature of a still moderately hot 81°F (27.2°C), subtly different from the previous month. In September, Lake Forest reports a consistent average low-temperature of 63.7°F (17.6°C) during the nights.Heat index
The heat index for September is appraised at 82.4°F (28°C). Extended exposure and activity might lead to tiredness, potentially resulting in heat cramps.It is worth noting that heat index values are gauged for conditions in the shade and light breezes. If directly exposed to the sun, the heat index could rise by 15 Fahrenheit (8 Celsius) degrees.
Note: The heat index, also known as 'felt air temperature' or 'real feel', is a composite of temperature and humidity figures to convey how warm it feels. The experience of temperature can be subjective, varying based on the individual's activity and heat perception, influenced by factors like wind, attire, and metabolic variations. Awareness is key; direct sunlight can enhance the weather's impact, possibly boosting the heat index by up to 15 Fahrenheit (8 Celsius) degrees. Heat index values are essentially critical for children. Young individuals are typically more threatened than adults due to their reduced perspiration. Also, the larger skin surface proportionate to their small bodies and the increased heat from their activities magnify their risk.
Humidity
In Lake Forest, the average relative humidity in September is 61%.Rainfall
In September, the rain falls for 4.6 days. Throughout September, 0.31" (8mm) of precipitation is accumulated. In Lake Forest, during the entire year, the rain falls for 65.4 days and collects up to 9.17" (233mm) of precipitation.Daylight
The average length of the day in September is 12h and 22min.On the first day of the month, sunrise is at 6:25 am and sunset at 7:15 pm. On the last day of September, sunrise is at 6:44 am and sunset at 6:35 pm PDT.
Sunshine
In September, the average sunshine is 10.6h.UV index
The months with the highest UV index are June through September, with an average maximum UV index of 6. A UV Index of 6 to 7 symbolizes a high threat to health from unprotected exposure to Sun's UV rays for the ordinary person.Note: In September, the maximum UV index of 6 suggests this advice:
Eschew overexposure. Those with light skin may suffer burns in fewer than 20 minutes. Be aware that the sun's UV radiation is strongest between 10 a.m. and 4 p.m. and try to reduce direct sun exposure during this period as much as possible. 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
What is the usual temperature for Lake Forest in September?
What is the average humidity in September in Lake Forest?
How many days does it rain in September?
How many hours of daylight does Lake Forest have in September?
What time are sunrise and sunset in September?
How many hours of sunshine does Lake Forest have in September?
What is the month with the highest UV index?
How high is the UV index in September?
Average temperature in September
Lake Forest, 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
Lake Forest, 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
Lake Forest, 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
Lake Forest, 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
Lake Forest, 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
Lake Forest, 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
Lake Forest, 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
Lake Forest, 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
Lake Forest, 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
Lake Forest, 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
Lake Forest, 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).
Lake Forest, California, USA
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