September weather forecast and climate
Bostonia, CA

Weather in September

September, the first month of the autumn, in Bostonia, is also a moderately hot month, with average temperature varying between 63.9°F (17.7°C) and 82.6°F (28.1°C).

Temperature

In September, the average high-temperature is essentially the same as in August - a still warm 82.6°F (28.1°C). The average low-temperature, in September, is 63.9°F (17.7°C).

Heat index

In September, the average heat index is appraised at 85.1°F (29.5°C). Exhaustion is likely with prolonged exposure and activity. Sustaining activity may result in heat cramps.
Take into consideration that the heat index values are calculated for shade and light wind conditions. 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 'real feel', 'apparent temperature', 'felt air temperature', or 'feels like', is what the temperature feels like to the human body when the air temperature is combined with the relative humidity. This effect is subjective, depending on the activity and individual's heat perception influenced by various reasons (wind, clothing, pregnancy). Bear in mind that direct sunshine exposure increases weather impact, and may raise heat index 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

In September, the average relative humidity is 59%.

Rainfall

In September, in Bostonia, the rain falls for 4.1 days. Throughout September, 0.31" (8mm) of precipitation is accumulated. In Bostonia, during the entire year, the rain falls for 56.1 days and collects up to 8.27" (210mm) of precipitation.

Daylight

In Bostonia, the average length of the day is 12.4h.

Sunshine

In September, the average sunshine is 10.4h.

UV index

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 health hazard from unprotected exposure to the Sun's UV rays for the average person.
Note: In September, the average maximum UV index of 6 translate into the following recommendations:
Take precautions against overexposure. Protection against sun damage is needed. 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. On bright days sunglasses that block both UVA and UVB rays should be worn. A hat with a wide brim is extremely helpful, as it can prevent roughly 50% of UV radiation from reaching the eyes.
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FAQ

What is the temperature in September in Bostonia?

The average high-temperature, in September, in Bostonia, is 82.6°F (28.1°C), while the average low-temperature is 63.9°F (17.7°C). The average heat index (a.k.a. 'real feel', 'apparent temperature'), that combines relative humidity and air temperature, in September is calculated to 85.1°F (29.5°C).

What is the average humidity in September in Bostonia?

The average relative humidity in September in Bostonia, California, is 59%.

How much does it rain in Bostonia in September?

In Bostonia, California, in September, during 4.1 rainfall days, 0.31" (8mm) of precipitation is typically accumulated.

How many hours of daylight does Bostonia have in September?

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

How long on average sun shines in September in Bostonia?

The average sunshine in September in Bostonia, California, is 10.4h.

What is the month with the highest UV index in Bostonia?

June through September, with an average maximum UV index of 6, are months with the highest UV index in Bostonia, California.

What is the UV index reading in September in Bostonia?

In Bostonia, California, the average daily maximum UV index in September is 6. A UV Index reading of 6 to 7 represents a high health threat from unsafe exposure to the Sun's UV rays.

Average temperature in September
Bostonia, CA

Average temperature in September - Bostonia, 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).

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Average pressure in September
Bostonia, CA

Average pressure in September - Bostonia, CA
  • Average pressure in September: 29.87"

The month with the highest atmospheric pressure is January (30.09").
Months with the lowest atmospheric pressure are June and September (29.87").

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Average wind speed in September
Bostonia, CA

Average wind speed in September - Bostonia, 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).

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Average humidity in September
Bostonia, CA

Average humidity in September - Bostonia, 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%).

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Average rainfall in September
Bostonia, CA

Average rainfall in September - Bostonia, 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").

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Average rainfall days in September
Bostonia, CA

Average rainfall days in September - Bostonia, 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).

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Average daylight in September /
Average sunshine in September
Bostonia, CA

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

The month with the longest days is June (Average daylight: 14.3h).
The month with the shortest days is December (Average daylight: 10h).

  • Average sunshine in September: 10.4h

The month with the most sunshine is July (Average sunshine: 12.1h).
The month with the least sunshine is December (Average sunshine: 6.7h).

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Average sunshine days in September
Bostonia, CA

Average sunshine days in September - Bostonia, 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).

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Average UV index in September
Bostonia, CA

Average UV index in September - Bostonia, CA
  • Average UV index in September: 6

Months with the highest UV index are June, July, August and September (UV index 6).
Months with the lowest UV index are January, February, November and December (UV index 4).

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Average cloud cover in September
Bostonia, CA

Average cloud cover in September - Bostonia, CA
  • Average cloud cover in September: 9

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).

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Average visibility in September
Bostonia, CA

Average visibility in September - Bostonia, 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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