September weather forecastEl Cajon, CA
September
Weather in September
September denotes a gentle shift from summer towards fall. The weather sees a reduction in temperature, with days becoming slightly cooler, providing respite from the summer heat. While the sun continues to bathe the city in its warmth, the declining daylight hours signal the onset of the autumn season. Despite the cooling temperatures, beach activities and water sports continue to be popular due to the warm ocean water. The temperature fluctuations reduce slightly, varying between 82.6°F (28.1°C) to 63.9°F (17.7°C), indicating the impending transition to cooler weather.Temperature
September's weather records an average high-temperature of a still warm 82.6°F (28.1°C), showing little deviation from August. El Cajon's nighttime temperature in September falls to an average of 63.9°F (17.7°C).Heat index
The heat index in September is computed to be 84.2°F (29°C). If one endures exposure and continues to be active, it might result in tiredness and heat cramps.When referencing the heat index, its values are suitable for shady environments and light breezes. Direct exposure to sunlight could raise the heat index by 15 Fahrenheit (8 Celsius) degrees.
Note: The heat index, also known as 'feels like' or 'felt air temperature', comes about by integrating the temperature readings with the humidity levels. This effect is personal, shaped by the individual's physical activity and heat sensitivity, influenced by factors including wind, clothing, and metabolic variances. Realize that direct exposure to sunlight can augment the felt heat, leading to a potential increase in the heat index by 15 Fahrenheit (8 Celsius) degrees. Heat index values hold particular significance 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 September, the average relative humidity is 59%.Rainfall
In El Cajon, during September, the rain falls for 4.1 days and regularly aggregates up to 0.31" (8mm) of precipitation. Throughout the year, there are 56.1 rainfall days, and 8.27" (210mm) of precipitation is accumulated.Daylight
The average length of the day in September is 12h and 22min.On the first day of September, sunrise is at 6:23 am and sunset at 7:12 pm. On the last day of the month, sunrise is at 6:41 am and sunset at 6:33 pm PDT.
Sunshine
In El Cajon, the average sunshine in September is 10.4h.UV index
The months with the highest UV index are June through September, with an average maximum UV index of 6. A UV Index value of 6 to 7 symbolizes a high health risk from exposure to the Sun's UV rays for ordinary individuals.Note: The UV index of 6 during September translates into the following guidance:
Use protective steps and abide by sun safety guidelines. Safeguarding against skin and eye harm is necessary. UV radiation from the Sun is most intense between 10 a.m. and 4 p.m. Try to avoid direct sunlight during this period. For a sun-safe wardrobe, go for clothes that are tightly woven and generously sized.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Average temperature in September
El Cajon, CA
- Average high temperature in September: 82.6°F
The warmest month (with the highest average high temperature) is August (83.8°F).
The month with the lowest average high temperature is December (63.7°F).
- Average low temperature in September: 63.9°F
The month with the highest average low temperature is August (65.8°F).
The coldest month (with the lowest average low temperature) is December (47.8°F).
Average pressure in September
El Cajon, CA
- Average pressure in September: 29.87"Hg
The month with the highest atmospheric pressure is January (30.09"Hg).
The months with the lowest atmospheric pressure are June and September (29.87"Hg).
Average wind speed in September
El Cajon, CA
- Average wind speed in September: 4.4mph
The windiest month (with the highest average wind speed) is April (5.5mph).
The calmest month (with the lowest average wind speed) is October (4.3mph).
Average humidity in September
El Cajon, CA
- Average humidity in September: 59%
The month with the highest relative humidity is May (66%).
The month with the lowest relative humidity is November (53%).
Average rainfall in September
El Cajon, CA
- Average rainfall in September: 0.31"
The wettest month (with the highest rainfall) is February (1.81").
The driest month (with the least rainfall) is June (0.04").
Average rainfall days in September
El Cajon, CA
- Average rainfall days in September: 4.1 days
The month with the highest number of rainy days is March (7.7 days).
The month with the least rainy days is June (1.4 days).
Average daylight in September /
Average sunshine in September
El Cajon, CA
- Average daylight in September: 12h and 24min
The month with the longest days is June (Average daylight: 14h and 18min).
The month with the shortest days is December (Average daylight: 10h and 0min).
- Average sunshine in September: 10h and 24min
The month with the most sunshine is July (Average sunshine: 12h and 6min).
The month with the least sunshine is December (Average sunshine: 6h and 42min).
Average sunshine days in September
El Cajon, CA
- Average sunshine days in September: 24.1 days
The month with the most sunshine days is June (27.7 days).
The month with the least sunshine days is February (21.9 days).
Average UV index in September
El Cajon, 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, November and December (UV index 4).
Average cloud cover in September
El Cajon, CA
- Average cloud cover in September: 9
The months with the most cloud cover are March and December (Cloud cover 23).
The month with the least cloud cover is August (Cloud cover 7).
Average visibility in September
El Cajon, 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).
