If you’ve ever driven North on the 101 toward San Francisco, you’ve seen the sign for Brisbane tucked against the slopes of San Bruno Mountain. Most people blow right past it. But for the 4,800 or so residents who call this place "The City of Stars," the weather in Brisbane California is a constant, shifting conversation piece that feels distinct from anywhere else in the Peninsula.
It’s weird. Honestly.
You can be standing in the South San Francisco sunshine, sweating in a t-shirt, and then drive three minutes into Brisbane only to find yourself engulfed in a thick, wet blanket of Pacific fog. It’s a microclimate in the truest sense of the word. Because the town is nestled in the "Guadalupe Valley" on the eastern flank of the mountain, it plays a high-stakes game of hide-and-seek with the sun every single day.
The San Bruno Mountain Effect
The big player here isn't the ocean or the bay directly—it's that massive hunk of rock and dirt called San Bruno Mountain.
Basically, the mountain acts as a massive physical barrier. It intercepts the cold, moist air screaming off the Pacific Ocean. When that air hits the ridge, it’s forced upward, cools, and condenses. This creates the infamous "fog cap" that can sit over Brisbane while downtown San Francisco is perfectly clear.
You’ve got to understand that Brisbane is often the first place the fog "pours" over. Locals call it the "fog waterfall." On a summer afternoon, you can actually watch the white mist tumble over the ridge like a slow-motion dam break. It’s beautiful, sure, but it means your BBQ plans are constantly at the mercy of the wind speed.
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Real Talk: The Temperature Reality
If you're looking for heat, you're in the wrong place.
- Highs: Usually top out around 72°F in September.
- Lows: Rarely dip below 45°F in January.
- The "Feel": Because of the wind, 60°F in Brisbane feels a lot like 50°F anywhere else.
Most "normal" places have four seasons. Brisbane has "Fog," "Wind," "That One Week of Summer," and "Rainy Season."
Why September is Actually the Best
Forget what you know about summer. June and July are often the most miserable months for anyone craving Vitamin D. This is the era of "June Gloom," where the sky stays a stubborn shade of battleship gray until 3:00 PM—if the sun comes out at all.
However, September and October are the real gems.
During these months, the inland valleys of California start to cool down, which weakens the "thermal draw" that pulls the ocean air through the Golden Gate and over San Bruno Mountain. The result? Crisp, clear blue skies and temperatures that actually hit the mid-70s. This is when the weather in Brisbane California finally rewards you for sticking out the damp spring.
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The Wind: Brisbane’s Invisible Resident
You can't talk about the weather here without mentioning the wind. It’s relentless.
June is statistically the windiest month, with gusts frequently hitting 25 mph or higher coming off the ridge. It’s a "clean" wind, sure, but it’ll knock over your patio furniture if you aren't careful. If you’re planning to hike the Ridge Trail on San Bruno Mountain, bring a windbreaker. No, seriously. Bring two. Even if it’s sunny at the trailhead, the summit is a different beast entirely.
Rain and the Atmospheric River
Brisbane gets about 20 inches of rain a year, which is pretty standard for the San Francisco Bay Area. But when it rains here, it pours. Because of the mountain’s topography, "orographic lift" can actually enhance rainfall totals during big Pacific storms.
In January 2026, we’ve seen how these atmospheric rivers can turn the steep canyons of Brisbane into temporary streams. If you’re looking at property here, the "low-lying" areas near the lagoon are much more prone to dampness than the "Upper Terrace" homes, though the Upper Terrace gets hit harder by the wind. It's a trade-off.
Navigating the Microclimates
It is entirely possible for it to be 68°F at the Brisbane Marina and 58°F up on Gladys Avenue.
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That 10-degree difference happens in less than a mile.
If you are visiting, the "Marina side" (east of 101) tends to be slightly more shielded from the direct mountain gusts but more exposed to the bay breeze. The "Hillside" (west of 101) is where the drama happens.
Practical Tips for Handling Brisbane Weather
If you're moving here or just visiting for a day of hiking, don't trust your iPhone's generic "San Francisco" forecast. It’s almost always wrong for Brisbane.
- The Layer Rule: This is cliché in California, but in Brisbane, it’s a survival tactic. You need a base layer for the sun, a fleece for the wind, and a shell for the fog.
- Check the Ridge: Look at the top of San Bruno Mountain. If you see the "white tablecloth" (fog) draped over the top, the temperature in town is about to drop 5 degrees in the next twenty minutes.
- Rust is Real: If you live on the hillside, the salt-heavy fog is a beast. Wash your car frequently and choose outdoor hardware that can handle high moisture.
- Gardening: Stick to native plants or those that thrive in "cool-summer" climates. Your tomatoes will struggle unless you have a very specific, sun-drenched south-facing wall.
The weather in Brisbane California isn't for everyone. It’s for people who like the moodiness of the coast without the crowds of the Pacific side. It’s for people who find a certain peace in the way the mist crawls through the eucalyptus trees at dusk.
To get the most accurate local reading, skip the national apps and check a personal weather station (PWS) located specifically in the 94005 zip code. This gives you the ground-truth data for the Guadalupe Valley rather than a generic reading from SFO airport, which is often warmer and less windy than Brisbane itself. Keep an eye on the wind direction; if it's coming from the West/Northwest, expect the fog to make an appearance by mid-afternoon.