September weather forecastSan Bernardino, CA
September
Weather in September
The first month of the autumn, September, is also a hot month in San Bernardino, California, with an average temperature varying between 87.4°F (30.8°C) and 63.3°F (17.4°C).Temperature
The start of September marks an average high-temperature of a still hot 87.4°F (30.8°C), hardly distinguishable from the conditions in August. San Bernardino, in September, experiences a marked contrast from daytime zeniths to a steady average low-temperature of 63.3°F (17.4°C).Heat index
The heat index value for September is computed to be a hot 87.8°F (31°C). One might feel worn out with persistent exposure and activity, resulting in heat cramps.Know that the heat index computations account for shaded terrains and slight 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 'feels like' or 'apparent temperature', is a measure that combines air temperature and relative humidity into a single value that indicates how hot the weather feels. Factors such as metabolic variations, being pregnant, and physical activity can impact an individual's weather perception. One's exposure to direct sunlight has the potential to intensify the heat sensation, increasing the heat index by up to 15 Fahrenheit (8 Celsius) degrees. Heat index values are quite important for babies and toddlers. 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
In September, the average relative humidity is 41%.Rainfall
In San Bernardino, in September, it is raining for 1.9 days, with typically 0.08" (2mm) of accumulated precipitation. Throughout the year, in San Bernardino, there are 46.6 rainfall days, and 6.18" (157mm) of precipitation is accumulated.Snowfall
In San Bernardino, snow does not fall in January, March through December.Daylight
In September, the average length of the day is 12h and 22min.On the first day of the month, sunrise is at 6:23 am and sunset at 7:14 pm. On the last day of September, in San Bernardino, sunrise is at 6:43 am and sunset at 6:34 pm PDT.
Sunshine
In September, the average sunshine in San Bernardino is 10.7h.UV index
In September, the average daily maximum UV index in San Bernardino is 6. A UV Index value of 6 to 7 symbolizes a high health hazard from exposure to the Sun's UV radiation for ordinary individuals.Note: An average maximum UV index of 6 in September leads to these recommendations:
Stick with precautions and abide by sun safety procedures. Evading sunburn is essential. The Sun's UV radiation is most potent between the hours of 10 a.m. and 4 p.m. Try to avoid direct sunlight during this time. A hat with a generous brim can prevent nearly 50% of UV rays from reaching your eyes.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Average temperature in September
San Bernardino, CA
- Average high temperature in September: 87.4°F
The warmest month (with the highest average high temperature) is August (91.9°F).
The month with the lowest average high temperature is December (59.9°F).
- Average low temperature in September: 63.3°F
The month with the highest average low temperature is August (65.8°F).
The coldest month (with the lowest average low temperature) is February (43.5°F).
Average pressure in September
San Bernardino, CA
- Average pressure in September: 29.87"Hg
The month with the highest atmospheric pressure is January (30.1"Hg).
The month with the lowest atmospheric pressure is June (29.85"Hg).
Average wind speed in September
San Bernardino, CA
- Average wind speed in September: 4.5mph
The windiest months (with the highest average wind speed) are April and May (6mph).
The calmest month (with the lowest average wind speed) is September (4.5mph).
Average humidity in September
San Bernardino, CA
- Average humidity in September: 41%
The month with the highest relative humidity is February (53%).
The month with the lowest relative humidity is August (38%).
Average rainfall in September
San Bernardino, CA
- Average rainfall in September: 0.08"
The wettest month (with the highest rainfall) is December (1.42").
The driest month (with the least rainfall) is June (0.04").
Average rainfall days in September
San Bernardino, CA
- Average rainfall days in September: 1.9 days
The month with the highest number of rainy days is March (6.7 days).
The month with the least rainy days is June (1.2 days).
Average snowfall days in September
San Bernardino, CA
- Average snowfall days in September: 0 days
The month with the highest number of snowfall days is February (0.1 days).
The months with the least snowfall days are January, March, April, May, June, July, August, September, October, November and December (0 days).
Average daylight in September /
Average sunshine in September
San Bernardino, CA
- Average daylight in September: 12h and 24min
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 42min
The month with the most sunshine is July (Average sunshine: 12h and 12min).
The month with the least sunshine is December (Average sunshine: 6h and 54min).
Average sunshine days in September
San Bernardino, CA
- Average sunshine days in September: 26.7 days
The months with the most sunshine days are June and October (27.9 days).
The month with the least sunshine days is February (21.7 days).
Average UV index in September
San Bernardino, CA
- Average UV index in September: 6
The months with the highest UV index are June, July and August (UV index 7).
The month with the lowest UV index is December (UV index 3).
Average cloud cover in September
San Bernardino, CA
- Average cloud cover in September: 6
The months with the most cloud cover are February and December (Cloud cover 21).
The month with the least cloud cover is August (Cloud cover 5).
Average visibility in September
San Bernardino, 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).
