Weather in San Francisco in August

Prime time. August is about as good as San Francisco gets. Highs average 23.6 °C, lows 13.2 °C, and rain falls on 0 days — nothing in the month is working against you.

August ranks 2 of 12 in San Francisco. Only July scores clearly higher, and the difference is small enough to be settled by price rather than weather.

Rain is not a factor worth planning around this month. Nothing specialised needed — this is the month you pack for the trip rather than for the weather.

What the averages hide

The averages here are honest — no hidden extremes worth planning around. Across the twenty years measured, the hottest August day reached 35.9 °C and the coldest night fell to 10.3 °C.

August is dependably dry, and that reliability is the point: across the twenty years measured, the wettest August on record still only managed 5 mm, and the driest managed 0 mm. There is no meaningful variability to plan around, which makes this one of the few months anywhere that you can build a fixed outdoor itinerary against without a fallback. The wettest single day in twenty years of Augusts brought 1 mm. Rain simply is not the variable that decides this trip — heat, crowds and cost are.

Wind is light at 8.1 km/h, so the temperature on the page is close to the temperature on your skin, and humidity is unremarkable at 74%.

How August sits in the year

Temperatures hold steady either side: 22.8 °C in July, 23.6 here, 24.5 in September. Nothing about the timing within the month matters much.

Daylight in August

13.7 hours of daylight, losing 1 hours across the month. That is between San Francisco's extremes of 14.8 and 9.6 hours, so days are long enough not to constrain the plan.

Sea temperature

The sea sits at about 15.5 °C in August — cold — a quick dip rather than a swim, and a wetsuit if you are in for longer. This is the warmest the water gets all year.

How busy it gets

Peak season. Expect the highest prices of the year and to be booking well ahead.

Crowd levels are estimated from climate desirability and school-holiday calendars, not from visitor numbers.

August in San Francisco versus nearby

If San Francisco is one option among several, the nearby comparison is worth making. Napa is the weaker option in August — 10.2 °C warmer, the same number of rain days. San Jose is the weaker option in August — 8 °C warmer, the same number of rain days.

So: August is effectively as good as it gets here — 0 points behind July, which is inside the margin where the weather stops being the deciding factor and price starts being it.

Every month in San Francisco

See all twelve months in San Francisco, or where else to go in August.