August in San Francisco is mild, dry and often gray: the downtown station averages a high of 67.9°F (19.9°C) and a low of 55.5°F (13.1°C), with almost no rain. Fog and low cloud cover the west side most mornings, while downtown and the Mission clear by afternoon, and warm days become more common late in the month.
Locals call it “Fogust,” and on the west side the nickname holds up. In NOAA's HRRR model analysis from 2014 to 2026, a low marine-layer cloud deck covered the Outer Sunset in three of every four 7 AM hours in August, more than in any other month.
What Is August Weather Like in San Francisco?
August weather in San Francisco is the hinge between peak fog and the city's warm season. The marine layer sits over the coast most often in August, yet downtown is already clearing more, the ocean is warming, and the last week of the month has produced some of the hottest summer days on record. Think of August as Fogust first, then the turn toward September.
| Average high / low | 67.9°F (19.9°C) / 55.5°F (13.1°C) |
|---|---|
| Average rain | Almost none: 0.06 in (1.5 mm) |
| Days at 70°F or warmer | About 10 |
| Fog and low cloud | West side most mornings; downtown clears more often than in July |
| Warmest part of the city | Mission District, about 72°F at 3 PM |
| Ocean temperature | About 57°F offshore; about 69°F in the bay at Alameda |
| Sunset | About 8:18 PM on Aug 1, 7:40 PM on Aug 31 |
San Francisco Downtown station (USW00023272), NOAA 1991-2020 normals via RCC-ACIS. Fog and neighborhood temperatures from NOAA High-Resolution Rapid Refresh (HRRR) model analysis, September 2014 to April 2026. Ocean temperatures from the NOAA NCEI Coastal Water Temperature Guide (buoy 46026 and Alameda 9414750). Sunset times computed for 2027.
Is August Really the Foggiest Month in San Francisco?
On the west side, August is the grayest month. The low marine-layer cloud deck covers the Outer Sunset in about 75% of 7 AM hours in August in HRRR analysis, more than any other month. Ground-level fog is a little less frequent than in July, 46% of 7 AM hours against 54%, and downtown clears noticeably more, with fog in about 24% of 7 AM hours against 35% in July.
So Fogust is real where most of the fog is, along the coast and through Golden Gate Park, and less so east of Twin Peaks. See when San Francisco's summer fog peaks and the science of Karl the Fog.
Why Does August Run Warmer Than July in San Francisco?
August runs warmer than July because the ocean is warming. The water off San Francisco averages about 57.2°F in August, up from 55.6°F in July, as the coastal northwest winds and upwelling ease; the afternoon wind at Crissy Field drops from about 18 mph in July to 17 mph in HRRR analysis. Downtown averages a 67.9°F high in August and about 10 days at 70°F or warmer, up from 7 in July.
Late August is when the pattern can break. All four of the hottest August days on record came in the last 8 days of the month: 98°F on August 24, 2010; 96°F on August 28, 2009, and August 29, 1968; and 95°F on August 27, 1993. From 1991 to 2020, about 7 Augusts in 10 reached 80°F at least once, and about 1 in 4 reached 90°F. The rest of the month is usually steady: about 23 days reach 65°F, and fewer than 1 day stays at or below 60°F.
The wind eases a little, too. In HRRR analysis, the 2 PM wind at Crissy Field averages about 17 mph in August, with about 4 in 5 afternoon hours at 15 mph or more, down from 9 in 10 in July. The bay shore is still breezy, but the edge comes off. For why the warm season comes so late, see why September is hotter than July.
How Different Is One August From the Next?
One August can be very different from the next. The average August high downtown ranged from 65.0°F in 2016 to 71.8°F in 2015, a wider swing than June or July; only September varies more. A strong, deep marine layer gives a cold, gray month, while a weak one gives the warm season an early start.
The practical lesson: check the 10-day forecast rather than trusting last year's trip. Whether the summer fog is thinning over the long term is a separate question, covered in our fog trends guide.
What Is the Weather Like for Outside Lands and Other August Events?
Outside Lands takes over western Golden Gate Park in early August. In HRRR analysis, fog covers the park in about 44% of 7 AM hours and 22% of 2 PM hours in August. Afternoons average about 63.5°F at 2 PM and drop into the upper 50s by 8 PM, and the music runs well after dark. Pack a warm layer and a light shell for fog drip under the trees. For festival planning, see Outside Lands weather and the Outside Lands forecast.
The free Stern Grove Festival wraps up its summer season in mid-August on the foggy southwest side of the city. Across the bay, outdoor events in downtown Oakland usually get more sun: it averages about 73°F at 3 PM in August.
Where Can You Find Sun and Warm Water in San Francisco in August?
For sun, head east and wait for midday. Fog in August is mostly a morning event downtown: in HRRR analysis it covers downtown in about 24% of 7 AM hours but only about 4% of 2 PM hours, so a gray start downtown is not a gray day. On the coast, it is different: the Outer Sunset still has fog in about 45% of 2 PM hours.
The Mission District averages about 72°F at 3 PM in August in HRRR analysis, 13 degrees warmer than the Outer Sunset. Oakland and Berkeley run warmer still, and Walnut Creek averages about 86°F. See San Francisco weather by neighborhood.
For warm water, head to the bay. The bay at Alameda peaks near 69°F in August, about 11 degrees warmer than the ocean off Ocean Beach. See Bay Area water temperatures and Bay Area beach day trips.
Is August a Good Time to Visit San Francisco?
August is a good time to visit San Francisco with the right expectations. It is dry, the days are long, with sunset moving from about 8:18 PM to 7:40 PM, and the evenings call for a jacket, not shorts. Days shrink from about 14.1 hours to 13.0 hours over the month, so late-August evenings feel noticeably earlier. Pack jeans, a T-shirt for sunny afternoons on the east side, a sweater and a windproof jacket; a beanie is not overkill for an evening at the beach or a festival in Golden Gate Park. Visitors who want warm city weather should look at September; see what to pack by month and San Francisco weather in July for the month before.
In August, check the Bay Area fog forecast the night before to see whether the fog will clear past Golden Gate Park, and compare the Outer Sunset with the Mission District before you pick a spot.