September weather forecast and climate
San Bernardino, CA

Scenic settlement spot on the foot of the iconic San Bernardino Mountains in California, with a view of the snow peaks of the San Gorgiono mountains
Scenic settlement spot on the foot of the iconic San Bernardino Mountains in California, with a view of the snow peaks of the San Gorgiono mountains

Weather in September

September, the first month of the autumn, in San Bernardino, is still a tropical month, with average temperature varying between 63.3°F (17.4°C) and 87.4°F (30.8°C).

Temperature

In September, the average high-temperature is essentially the same as in August - a still tropical 87.4°F (30.8°C). The average low-temperature, is 63.3°F (17.4°C).

Heat index

The average heat index in September is calculated to a tropical 87.4°F (30.8°C). Constant exposure and activity lead to possible fatigue. Prolonged exercise may result in heat cramps.
Note that heat index values are valued for light wind and location in the shade. With the exposure to direct sunlight, the heat index may be increased by up to 15 Fahrenheit (8 Celsius) degrees.
Note: The heat index, also known as 'apparent temperature', 'feels like', 'felt air temperature', or 'real feel', is a calculated temperature value of how hot it feels when the moisture in the air is factored in. Additional factors like wind, clothing, metabolic differences, and activity influence one's weather impression. Be aware that direct exposure to sunlight increases heat impact, and may raise the heat index additionally, by up to 15 Fahrenheit (8 Celsius) degrees. Heat index values are especially crucial for babies and toddlers. Young children are generally more endangered than adults, as they usually less sweat. And also, due to larger skin surface relative to their small bodies and higher heat production as a result of their activity.

Humidity

The average relative humidity in San Bernardino is 41%.

Rainfall

In September, in San Bernardino, the rain falls for 1.9 days. Throughout September, 0.08" (2mm) of precipitation is accumulated. Throughout the year, 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

The average length of the day in San Bernardino is 12.4h.

Sunshine

In September, the average sunshine is 10.7h.

UV index

The average daily maximum UV index in September is 6. A UV Index of 6 to 7 symbolizes a high threat to health from the exposure to the Sun's UV radiation for the ordinary person.
Note: The average daily UV index of 6 transform into the following instructions:
Take precautions and adopt sun safety practices. Protection against sunburn is obliged. Seek shade and minimize exposure to direct Sun in a period between 10 a.m. and 4 p.m. when UV radiation is most intense; keep in mind that shade structures like parasols or canopies do not provide perfect sun protection. Sun-protective clothing, a long-sleeved shirt and pants, a wide-brimmed hat, and UVA and UVB-blocking sunglasses are particularly helpful in blocking UV radiation's harmful effects.
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FAQ

What is the temperature in September in San Bernardino?

In San Bernardino, in September, the average high-temperature is 87.4°F (30.8°C), and the average low-temperature is 63.3°F (17.4°C). The average heat index (a.k.a. 'apparent temperature', 'feels like'), that takes the relative humidity and factores it into the air temperature reading, in September is appraised at 87.4°F (30.8°C).

What is the average humidity in September in San Bernardino?

In San Bernardino, California, the average relative humidity in September is 41%.

How many days does it rain in September in San Bernardino?

In September, in San Bernardino, the rain falls for 1.9 days. Throughout September, 0.08" (2mm) of precipitation is accumulated.

When it does not snow in San Bernardino?

In San Bernardino, California, snow does not fall in January, March through December.

What is the average length of the day in September in San Bernardino?

In September, the average length of the day in San Bernardino, California, is 12.4h.

How many hours of sunshine does San Bernardino have in September?

In September, the average sunshine in San Bernardino, California, is 10.7h.

How high is the UV index in September in San Bernardino?

The average daily maximum UV index in September in San Bernardino, California, is 6. A UV Index of 6 to 7 symbolizes a high health risk from unsafe exposure to the Sun's UV rays.

Average temperature in September
San Bernardino, CA

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).

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Average pressure in September
San Bernardino, CA

Average pressure in September - San Bernardino, CA
  • Average pressure in September: 29.87"

The month with the highest atmospheric pressure is January (30.1").
The month with the lowest atmospheric pressure is June (29.85").

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Average wind speed in September
San Bernardino, CA

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).

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Average humidity in September
San Bernardino, CA

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%).

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Average rainfall in September
San Bernardino, CA

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").

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Average rainfall days in September
San Bernardino, CA

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).

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Average snowfall days in September
San Bernardino, CA

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).
Months with the least snowfall days are January, March, April, May, June, July, August, September, October, November and December (0 days).

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Average daylight in September /
Average sunshine in September
San Bernardino, CA

Average daylight in September / Average sunshine in September - San Bernardino, CA
  • Average daylight in September: 12.4h

The month with the longest days is June (Average daylight: 14.4h).
The month with the shortest days is December (Average daylight: 9.9h).

  • Average sunshine in September: 10.7h

The month with the most sunshine is July (Average sunshine: 12.2h).
The month with the least sunshine is December (Average sunshine: 6.9h).

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Average sunshine days in September
San Bernardino, CA

Average sunshine days in September - San Bernardino, CA
  • Average sunshine days in September: 26.7 days

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).

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Average UV index in September
San Bernardino, CA

Average UV index in September - San Bernardino, CA
  • Average UV index in September: 6

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).

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Average cloud cover in September
San Bernardino, CA

Average cloud cover in September - San Bernardino, CA
  • Average cloud cover in September: 6

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).

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Average visibility in September
San Bernardino, CA

Average visibility in September - San Bernardino, CA
  • Average visibility in September: 6mi

Months with the highest visibility are January, February, March, April, May, June, July, August, September, October, November and December (6mi).
Months with the lowest visibility are January, February, March, April, May, June, July, August, September, October, November and December (6mi).

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