September weather forecast and climate
Mountain View, CA

A street in Mountain View Town, California, with neon-lit building, trees, and parked cars
A street in Mountain View Town, California, with neon-lit building, trees, and parked cars

Weather in September

September, the first month of the autumn, in Mountain View, is also a moderately hot month, with average temperature ranging between min 56.1°F (13.4°C) and max 77.9°F (25.5°C).

Temperature

In September, the average high-temperature is practically the same as in August - a still moderately hot 77.9°F (25.5°C). In Mountain View, the average low-temperature is 56.1°F (13.4°C).

Humidity

July, September and October, with an average relative humidity of 63%, are the least humid months in Mountain View.

Rainfall

In Mountain View, California, in September, during 2.3 rainfall days, 0.08" (2mm) of precipitation is typically accumulated. In Mountain View, during the entire year, the rain falls for 53.1 days and collects up to 4.41" (112mm) of precipitation.

Daylight

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

Sunshine

In September, the average sunshine is 11h.

UV index

The average daily maximum UV index in Mountain View is 5. A UV Index value of 3 to 5 symbolizes a medium vulnerability from unsafe exposure to the UV radiation for the average person.
Note: The average daily UV index of 5 transform into the following instructions:
Take precautions - Protection against the skin and eye damage is obliged. The solar radiation is most powerful near the mid-day, so the exposure to the direct Sun should be reduced accordingly. A wide-brim hat offers excellent sun protection for eyes, ears, face, and neck. Sunglasses with UVA and UVB protection significantly reduce eye damage from sun exposure. Tightly woven, loose-fitting clothes provide additional protection from the Sun.
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FAQ

What is the temperature in September in Mountain View?

In Mountain View, California, in September, the average high-temperature is 77.9°F (25.5°C), and the average low-temperature is 56.1°F (13.4°C).

What is the least humid month in Mountain View?

July, September and October, with an average relative humidity of 63%, are the least humid months in Mountain View, California.

What is the average humidity in September in Mountain View?

The average relative humidity in September in Mountain View is 63%.

How many days does it rain in September in Mountain View?

In Mountain View, California, in September, it is raining for 2.3 days, with typically 0.08" (2mm) of accumulated precipitation.

What is the average length of the day in September in Mountain View?

The average length of the day in September in Mountain View is 12.4h.

How many hours of sunshine does Mountain View have in September?

In September, the average sunshine in Mountain View is 11h.

What is the UV index intensity in September in Mountain View?

The average daily maximum UV index in September in Mountain View, California, is 5. A UV Index value of 3 to 5 symbolizes a medium health risk from unprotected exposure to the UV radiation.

Average temperature in September
Mountain View, CA

Average temperature in September - Mountain View, CA
  • Average high temperature in September: 77.9°F

The warmest month (with the highest average high temperature) is July (79.7°F).
The month with the lowest average high temperature is December (56.5°F).

  • Average low temperature in September: 56.1°F

The month with the highest average low temperature is August (56.8°F).
The coldest month (with the lowest average low temperature) is December (44.1°F).

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Average pressure in September
Mountain View, CA

Average pressure in September - Mountain View, CA
  • Average pressure in September: 29.92"

The month with the highest atmospheric pressure is January (30.13").
Months with the lowest atmospheric pressure are June and September (29.92").

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Average wind speed in September
Mountain View, CA

Average wind speed in September - Mountain View, CA
  • Average wind speed in September: 4.7mph

The windiest months (with the highest average wind speed) are April and May (6.2mph).
The calmest months (with the lowest average wind speed) are August, September, October and November (4.7mph).

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Average humidity in September
Mountain View, CA

Average humidity in September - Mountain View, CA
  • Average humidity in September: 63%

The month with the highest relative humidity is March (73%).
Months with the lowest relative humidity are July, September and October (63%).

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Average rainfall in September
Mountain View, CA

Average rainfall in September - Mountain View, CA
  • Average rainfall in September: 0.08"

The wettest months (with the highest rainfall) are February, March and December (0.83").
The driest months (with the least rainfall) are June, July and August (0.04").

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Average rainfall days in September
Mountain View, CA

Average rainfall days in September - Mountain View, CA
  • Average rainfall days in September: 2.3 days

The month with the highest number of rainy days is March (10 days).
The month with the least rainy days is August (0.4 days).

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Average daylight in September /
Average sunshine in September
Mountain View, CA

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

The month with the longest days is June (Average daylight: 14.7h).
The month with the shortest days is December (Average daylight: 9.6h).

  • Average sunshine in September: 11h

Months with the most sunshine are July and August (Average sunshine: 12h).
The month with the least sunshine is December (Average sunshine: 5.9h).

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Average sunshine days in September
Mountain View, CA

Average sunshine days in September - Mountain View, CA
  • Average sunshine days in September: 27.5 days

Months with the most sunshine days are July and August (29.8 days).
The month with the least sunshine days is March (19.4 days).

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Average UV index in September
Mountain View, CA

Average UV index in September - Mountain View, CA
  • Average UV index in September: 5

The month with the highest UV index is June (UV index 6).
Months with the lowest UV index are February, November and December (UV index 3).

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Average cloud cover in September
Mountain View, CA

Average cloud cover in September - Mountain View, CA
  • Average cloud cover in September: 11

The month with the most cloud cover is March (Cloud cover 35).
The month with the least cloud cover is July (Cloud cover 7).

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Average visibility in September
Mountain View, CA

Average visibility in September - Mountain View, 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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