August weather forecast
Portola Valley, CA

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Weather in August

August, the last month of the summer in Portola Valley, is another pleasant month, with an average temperature fluctuating between 56.7°F (13.7°C) and 73°F (22.8°C).

Temperature

August registers as the month with the highest average temperatures, reaching 73°F (22.8°C) at its peak and 56.7°F (13.7°C) at the lowest.

Humidity

In August, the average relative humidity in Portola Valley, California, is 74%.

Rainfall

In Portola Valley, California, in August, during 1 rainfall days, 0.08" (2mm) of precipitation is typically accumulated. In Portola Valley, during the entire year, the rain falls for 57.5 days and collects up to 4.76" (121mm) of precipitation.

Daylight

In Portola Valley, California, the average length of the day in August is 13h and 33min.
On the first day of the month, sunrise is at 6:14 am and sunset at 8:16 pm. On the last day of August, sunrise is at 6:39 am and sunset at 7:38 pm PDT.

Sunshine

In Portola Valley, the average sunshine in August is 11.9h.

UV index

The months with the highest UV index are June through September, with an average maximum UV index of 5. A UV Index estimate of 3 to 5 represents a medium health hazard from exposure to the Sun's UV radiation for the average person.
Note: The UV index of 5 during August translates into the following guidance:
Make use of precautions - Suggestions to resist sunburn are communicated. Avoiding the Sun during its peak radiation time around midday is a healthy practice. Sunglasses that guard against UVA and UVB rays are pivotal in minimizing sun-induced ocular damage.
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Frequently asked questions

What part of the year is the hottest in Portola Valley?

During the warmest month in Portola Valley, August, temperatures average a high of 73°F (22.8°C) and a low of 56.7°F (13.7°C).

What are August temperatures in Portola Valley?

The average high-temperature, in August, in Portola Valley, is 73°F (22.8°C), while the average low-temperature is 56.7°F (13.7°C).

What is the average humidity in August in Portola Valley?

The average relative humidity in August is 74%.

How many days does it rain in August in Portola Valley?

In Portola Valley, in August, it is raining for 1 days, with typically 0.08" (2mm) of accumulated precipitation.

How many hours of daylight does Portola Valley have in August?

In Portola Valley, California, the average day length in August is 13h and 33min.

What time are sunrise and sunset in August in Portola Valley?

In August, on the first day of the month, sunrise is at 6:14 am and sunset at 8:16 pm. On the last day of the month, in Portola Valley, California, sunrise is at 6:39 am and sunset at 7:38 pm PDT.

How many hours of sunshine does Portola Valley have in August?

In August, the average sunshine duration is 11.9h.

What are the months with the highest UV index in Portola Valley?

The months with the highest UV index in Portola Valley, California, are June through September, with an average maximum UV index of 5.

What is the UV index intensity in August in Portola Valley?

In August, the average daily maximum UV index in Portola Valley is 5. A UV Index reading of 3 to 5 represents a medium health risk from unsafe exposure to Sun's UV rays.
Average humidity
Average rainfall days
Average daylight
Average sunshine
Average sunshine days
Average UV index
Average cloud cover
Average visibility

Average temperature in August
Portola Valley, CA

Average temperature in August - Portola Valley, CA
  • Average high temperature in August: 73°F

The warmest month (with the highest average high temperature) is August (73°F).
The month with the lowest average high temperature is December (55.8°F).

  • Average low temperature in August: 56.7°F

The months with the highest average low temperature are August and September (56.7°F).
The coldest months (with the lowest average low temperature) are January and February (46.4°F).

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Average pressure in August
Portola Valley, CA

Average pressure in August - Portola Valley, CA
  • Average pressure in August: 29.93"Hg

The month with the highest atmospheric pressure is January (30.13"Hg).
The month with the lowest atmospheric pressure is September (29.92"Hg).

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Average wind speed in August
Portola Valley, CA

Average wind speed in August - Portola Valley, CA
  • Average wind speed in August: 5.5mph

The windiest month (with the highest average wind speed) is April (7.6mph).
The calmest month (with the lowest average wind speed) is August (5.5mph).

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Average humidity in August
Portola Valley, CA

Average humidity in August - Portola Valley, CA
  • Average humidity in August: 74%

The month with the highest relative humidity is March (76%).
The month with the lowest relative humidity is October (68%).

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Average rainfall in August
Portola Valley, CA

Average rainfall in August - Portola Valley, CA
  • Average rainfall in August: 0.08"

The wettest month (with the highest rainfall) is February (0.98").
The driest month (with the least rainfall) is June (0.04").

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Average rainfall days in August
Portola Valley, CA

Average rainfall days in August - Portola Valley, CA
  • Average rainfall days in August: 1 days

The month with the highest number of rainy days is March (10.6 days).
The month with the least rainy days is June (0.9 days).

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Average daylight in August /
Average sunshine in August
Portola Valley, CA

Average daylight in August / Average sunshine in August - Portola Valley, CA
  • Average daylight in August: 13h and 4min

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 August: 11h and 5min

The month with the most sunshine is July (Average sunshine: 12h and 0min).
The month with the least sunshine is December (Average sunshine: 5h and 54min).

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Average sunshine days in August
Portola Valley, CA

Average sunshine days in August - Portola Valley, CA
  • Average sunshine days in August: 24.2 days

The months with the most sunshine days are June and July (26.3 days).
The month with the least sunshine days is March (18.3 days).

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Average UV index in August
Portola Valley, CA

Average UV index in August - Portola Valley, CA
  • Average UV index in August: 5

The months with the highest UV index are June, July, August and September (UV index 5).
The months with the lowest UV index are February, November and December (UV index 3).

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Average cloud cover in August
Portola Valley, CA

Average cloud cover in August - Portola Valley, CA
  • Average cloud cover in August: 11

The month with the most cloud cover is March (Cloud cover 35).
The month with the least cloud cover is July (Cloud cover 9).

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Average visibility in August
Portola Valley, CA

Average visibility in August - Portola Valley, CA
  • Average visibility in August: 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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Portola Valley, California, USA

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