September weather forecast
San Ramon, CA

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A street in San Ramon, California, featuring a stunning beauty of golden and brown trees on both sides of the road, during autumn
A street in San Ramon, California, featuring a stunning beauty of golden and brown trees on both sides of the road, during autumn

Weather in September

The first month of the autumn, September, is still a warm month in San Ramon, California, with temperature in the range of an average low of 56.5°F (13.6°C) and an average high of 82°F (27.8°C).

Temperature

San Ramon observes an average high-temperature of a still warm 82°F (27.8°C) in September, barely different from 83.3°F (28.5°C) in August. San Ramon logs a notable disparity from the daily highs during September, as the nighttime temperature lowers to an average of 56.5°F (13.6°C).

Heat index

The heat index value during September is estimated at 84.2°F (29°C). If one endures exposure and continues to be active, it might result in tiredness and heat cramps.
Take into consideration that the heat index values are calculated for shade and light wind conditions. If directly exposed to the sun, the heat index could rise by 15 Fahrenheit (8 Celsius) degrees.
Note: The heat index, also known as 'feels like' or 'real feel', is a numerical representation of warmth when taking temperature and moisture levels into account. Elements such as metabolic variations, being pregnant, and physical activity can impact one's weather perception. In the direct sunlight, the weather's impact can be amplified, possibly boosting the heat index by up to 15 Fahrenheit (8 Celsius) degrees. Heat index values are extremely significant for babies and toddlers. Children often fail to recognize the requirement to rest and rehydrate. Thirst, being a late symptom of dehydration, underlines the importance of maintaining hydration, especially during ongoing physical activities.

Humidity

The least humid month is September, with an average relative humidity of 57%.

Rainfall

In San Ramon, during September, the rain falls for 1.8 days and regularly aggregates up to 0.08" (2mm) of precipitation. In San Ramon, during the entire year, the rain falls for 67.2 days and collects up to 10.98" (279mm) of precipitation.

Daylight

The average length of the day in September is 12h and 25min.
On the first day of the month, sunrise is at 6:38 am and sunset at 7:36 pm. On the last day of September, in San Ramon, sunrise is at 7:03 am and sunset at 6:51 pm PDT.

Sunshine

In September, the average sunshine is 11.2h.

UV index

The average daily maximum UV index in September is 5. A UV Index reading of 3 to 5 represents a moderate health risk from exposure to the Sun's UV rays for average individuals.
Note: A daily high UV index of 5 in September leads to these guidelines:
Proceed with care. Light skin individuals may be exposed to burns in fewer than 30 minutes. Avoiding the Sun's peak radiation during midday hours is essential for health and safety. For a sun-safe wardrobe, go for clothes that are tightly woven and generously sized.
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Frequently asked questions

What are September temperatures in San Ramon?

The average high-temperature, in September, in San Ramon, is 82°F (27.8°C), while the average low-temperature is 56.5°F (13.6°C). The average heat index (a.k.a. 'real feel', 'feels like'), which calculates the temperature value influenced by the moisture in the air, in September is estimated at 84.2°F (29°C).

What is the least humid month in San Ramon?

With an average relative humidity of 57%, September is the least humid month in San Ramon, California.

What is the average humidity in September in San Ramon?

The average relative humidity in September is 57%.

How much does it rain in San Ramon in September?

In San Ramon, during September, the rain falls for 1.8 days and regularly aggregates up to 0.08" (2mm) of precipitation.

How many hours of daylight does San Ramon have in September?

In September, the average day length in San Ramon is 12h and 25min.

When is the sunrise / sunset in September in San Ramon?

On the first day of September in San Ramon, sunrise is at 6:38 am and sunset at 7:36 pm. On the last day of the month, sunrise is at 7:03 am and sunset at 6:51 pm PDT.

How long on average sun shines in September in San Ramon?

In September, the average sunshine duration in San Ramon is 11.2h.

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

In San Ramon, the average daily maximum UV index in September is 5. A UV Index of 3 to 5 symbolizes a moderate vulnerability from unprotected exposure to UV radiation.
Average humidity
Average rainfall days
Average daylight
Average sunshine
Average sunshine days
Average UV index
Average cloud cover
Average visibility

Average temperature in September
San Ramon, CA

Average temperature in September - San Ramon, CA
  • Average high temperature in September: 82°F

The warmest month (with the highest average high temperature) is July (83.7°F).
The month with the lowest average high temperature is December (55.9°F).

  • Average low temperature in September: 56.5°F

The month with the highest average low temperature is September (56.5°F).
The coldest month (with the lowest average low temperature) is December (42.1°F).

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Average pressure in September
San Ramon, CA

Average pressure in September - San Ramon, CA
  • Average pressure in September: 29.92"Hg

The month with the highest atmospheric pressure is January (30.14"Hg).
The months with the lowest atmospheric pressure are June, August and September (29.92"Hg).

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Average wind speed in September
San Ramon, CA

Average wind speed in September - San Ramon, CA
  • Average wind speed in September: 5.2mph

The windiest month (with the highest average wind speed) is May (6.7mph).
The calmest month (with the lowest average wind speed) is November (4.2mph).

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Average humidity in September
San Ramon, CA

Average humidity in September - San Ramon, CA
  • Average humidity in September: 57%

The month with the highest relative humidity is March (74%).
The month with the lowest relative humidity is September (57%).

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Average rainfall in September
San Ramon, CA

Average rainfall in September - San Ramon, CA
  • Average rainfall in September: 0.08"

The wettest month (with the highest rainfall) is February (2.28").
The driest month (with the least rainfall) is July (0").

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Average rainfall days in September
San Ramon, CA

Average rainfall days in September - San Ramon, CA
  • Average rainfall days in September: 1.8 days

The month with the highest number of rainy days is March (12.6 days).
The month with the least rainy days is August (0.6 days).

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

Average daylight in September / Average sunshine in September - San Ramon, CA
  • Average daylight in September: 12h and 2min

The month with the longest days is June (Average daylight: 14h and 42min).
The month with the shortest days is December (Average daylight: 9h and 36min).

  • Average sunshine in September: 11h and 1min

The month with the most sunshine is July (Average sunshine: 12h and 6min).
The month with the least sunshine is December (Average sunshine: 5h and 48min).

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Average sunshine days in September
San Ramon, CA

Average sunshine days in September - San Ramon, CA
  • Average sunshine days in September: 27.5 days

The month with the most sunshine days is July (29.9 days).
The month with the least sunshine days is March (17.5 days).

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Average UV index in September
San Ramon, CA

Average UV index in September - San Ramon, CA
  • Average UV index in September: 5

The months with the highest UV index are June, July and August (UV index 6).
The months with the lowest UV index are January, February, November and December (UV index 3).

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Average cloud cover in September
San Ramon, CA

Average cloud cover in September - San Ramon, CA
  • Average cloud cover in September: 10

The month with the most cloud cover is March (Cloud cover 36).
The month with the least cloud cover is July (Cloud cover 6).

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Average visibility in September
San Ramon, CA

Average visibility in September - San Ramon, 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).

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San Ramon, California, USA

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