August weather forecast
San Francisco, CA

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A beautiful dusk view of the Golden Gate Bridge in San Francisco, California
A beautiful dusk view of the Golden Gate Bridge in San Francisco, California

Weather in August

August carries forward the city's quintessential cool and mild summer. This month sees only a marginal increase in temperature from July, hitting a tepid peak of 72.5°F (22.5°C). Suns set late, allowing long, comfortable evenings for alfresco dining or evening strolls. San Francisco's notorious fog can roll in unexpectedly, creating gorgeous sunsets over the ocean. Moving into September, anticipate the continuation of pleasant summer-like conditions with slight cooling trends.

Temperature

San Francisco, California, experiences an average high-temperature of a still agreeable 72.5°F (22.5°C) in August, subtly different from July's 72.1°F (22.3°C). During the month of August, an average temperature of 56.3°F (13.5°C) is noted during the nights in San Francisco.

Humidity

In August, the average relative humidity is 74%.

Rainfall

July through September are months with the least rain in San Francisco when the rain falls for 2.7 days and typically aggregates up to 0.08" (2mm) of rain.

Ocean temperature

In San Francisco, the average seawater temperature in August is 56.7°F (13.7°C).
Note: With an efficient thermal swimsuit, one can navigate 56.7°F (13.7°C) even if it's colder than 50°F (10°C); otherwise, rapid cold shock and breathlessness might set in. Barely wading at 55.4°F (13°C) feels chilly.

Daylight

In August, the average length of the day is 13h and 34min.
On the first day of August, sunrise is at 6:13 am and sunset at 8:17 pm. On the last day of the month, sunrise is at 6:39 am and sunset at 7:39 pm PDT.

Sunshine

In San Francisco, the average sunshine in August is 11.6h.

UV index

The months with the highest UV index are April, June through September, with an average maximum UV index of 5. A UV Index value of 3 to 5 symbolizes a moderate threat to health from exposure to the Sun's UV rays for the ordinary person.
Note: In August, the average maximum UV index of 5 translates into the following recommendations:
Undertake precautions - Guarding against sun damage is counselled. Avoiding the Sun's peak radiation during midday hours is essential for health and safety. By wearing a generously brimmed hat, you can cut UV radiation exposure significantly.
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Frequently asked questions

What is the temperature in August in San Francisco?

The high-temperature, in August, in San Francisco, records 72.5°F (22.5°C), while the low-temperature is 56.3°F (13.5°C).

What is the average humidity in August in San Francisco?

In San Francisco, the average relative humidity in August is 74%.

What is the driest month in San Francisco?

July through September are months with the least rain in San Francisco when the rain falls for 2.7 days and typically aggregates up to 0.08" (2mm) of rain.

How many days does it rain in August in San Francisco?

In San Francisco, during August, the rain falls for 2.7 days and regularly aggregates up to 0.08" (2mm) of precipitation.

What is the water temperature in August in San Francisco?

In San Francisco, in August, the average water temperature is 56.7°F (13.7°C). Swimming in 56.7°F (13.7°C) is considered life-threatening. Even a few minutes in 55.4°F (13°C) water is uncomfortable, and swimming below 50°F (10°C) may cause total loss of breathing control and cold shock, depending on a person's physique.

How many hours of daylight does San Francisco have in August?

In San Francisco, California, the average day length in August is 13h and 34min.

When is the sunrise / sunset in August in San Francisco?

In August, on the first day of the month, sunrise is at 6:13 am and sunset at 8:17 pm. On the last day of the month, in San Francisco, sunrise is at 6:39 am and sunset at 7:39 pm PDT.

How many hours of sunshine does San Francisco have in August?

In August, the average sunshine duration in San Francisco, California, is 11.6h.

What are the months with the highest UV index in San Francisco?

April, June through September, with an average maximum UV index of 5, are months with the highest UV index in San Francisco, California.

What is the UV index reading in August in San Francisco?

The average daily maximum UV index in August in San Francisco is 5. A UV Index estimate of 3 to 5 represents a medium health risk from 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
San Francisco, CA

Average temperature in August - San Francisco, CA
  • Average high temperature in August: 72.5°F

The warmest month (with the highest average high temperature) is September (73.2°F).
The month with the lowest average high temperature is December (55.8°F).

  • Average low temperature in August: 56.3°F

The month with the highest average low temperature is September (56.7°F).
The coldest months (with the lowest average low temperature) are January and December (45.9°F).

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Average pressure in August
San Francisco, CA

Average pressure in August - San Francisco, CA
  • Average pressure in August: 29.92"Hg

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

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Average wind speed in August
San Francisco, CA

Average wind speed in August - San Francisco, CA
  • Average wind speed in August: 6.2mph

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

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Average humidity in August
San Francisco, CA

Average humidity in August - San Francisco, 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 (67%).

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Average rainfall in August
San Francisco, CA

Average rainfall in August - San Francisco, CA
  • Average rainfall in August: 0.08"

The wettest month (with the highest rainfall) is February (1.38").
The driest months (with the least rainfall) are July, August and September (0.08").

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Average rainfall days in August
San Francisco, CA

Average rainfall days in August - San Francisco, CA
  • Average rainfall days in August: 2.7 days

The month with the highest number of rainy days is March (9.3 days).
The month with the least rainy days is June (1.9 days).

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Average sea temperature in August
San Francisco, CA

Average sea temperature in August - San Francisco, CA
  • Average sea temperature in August: 56.7°F

The best month for swimming (with the highest average sea temperature) is September (57.3°F).
The coldest months (with the lowest average sea temperature) are April and June (53°F).

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Average daylight in August /
Average sunshine in August
San Francisco, CA

Average daylight in August / Average sunshine in August - San Francisco, 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 4min

The month with the most sunshine is July (Average sunshine: 11h and 48min).
The month with the least sunshine is December (Average sunshine: 5h and 48min).

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Average sunshine days in August
San Francisco, CA

Average sunshine days in August - San Francisco, CA
  • Average sunshine days in August: 23.1 days

The month with the most sunshine days is October (25.8 days).
The month with the least sunshine days is March (20.8 days).

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Average UV index in August
San Francisco, CA

Average UV index in August - San Francisco, CA
  • Average UV index in August: 5

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

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Average cloud cover in August
San Francisco, CA

Average cloud cover in August - San Francisco, CA
  • Average cloud cover in August: 16

The month with the most cloud cover is March (Cloud cover 36).
The months with the least cloud cover are July and September (Cloud cover 14).

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Average visibility in August
San Francisco, CA

Average visibility in August - San Francisco, 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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San Francisco, California, USA

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