You’ve probably seen the photo. A tourist standing on the Golden Gate Bridge in July, shivering in a thin souvenir t-shirt, looking like they’ve made a terrible mistake. They have. If you’re trying to figure out the temperature of San Francisco, looking at a map of California won't help you much. In fact, it might actually lie to you.
San Francisco is a meteorological weirdo.
Most people expect California to be all sunshine and palm trees. But here, the weather is governed by a giant, invisible air conditioner called the Pacific Ocean. While the rest of the country is sweltering in 90-degree heat, San Francisco is often trapped in a grey, damp embrace that locals call "June Gloom" or "Fogust." It’s weird. It’s inconsistent. And honestly, it’s why the city sells more hoodies than anywhere else on the planet.
What is the Temperature of San Francisco Right Now (and Why it Changes by Block)
The official temperature of San Francisco is usually measured at the airport (SFO) or downtown, but those numbers are basically useless if you’re actually walking around. The city is built on roughly 50 hills. This creates "microclimates." You can be in the Mission District basking in 75-degree sun, walk twenty minutes toward the Sunset District, and suddenly find yourself in a 55-degree wind tunnel.
The Pacific Ocean stays cold—around 52 to 58 degrees—all year. When hot air from the inland valleys rises, it pulls that cold, moist oceanic air through the Golden Gate gap. This creates the famous fog. Because the fog hits the western side of the city first, the Richmond and Sunset neighborhoods are almost always 10 degrees colder than the eastern side, like Dogpatch or Mission Bay.
The Summer Myth
July is not summer here. Not really.
If you look at the historical data from the National Weather Service, you'll see that the average high in July is only about 67°F (19°C). That sounds pleasant, right? It isn't. That average includes the sunny hours between 1 PM and 4 PM. Before and after that window, the wind kicks up, the fog rolls in, and it feels like 50 degrees.
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Mark Twain probably never actually said "the coldest winter I ever spent was a summer in San Francisco," but the fact that everyone attributes it to him tells you everything you need to know.
When is San Francisco Actually Warm?
Surprisingly, the best temperature of San Francisco occurs in September and October. This is what locals call "Indian Summer." The inland heat dies down, the pressure gradient shifts, and the fog stays out at sea.
During these months, you finally get those 75 or 80-degree days that people associate with California. The parks fill up. People finally take off their North Face jackets. It's glorious, but it’s brief. By November, the rain starts to peek through, and the damp chill of winter sets in.
Winter isn't "snowy" cold, but it’s "bone-deep" cold. Because the humidity is high, a 45-degree morning in San Francisco feels significantly more biting than a 30-degree morning in a dry place like Denver.
Breaking Down the Seasons (The Real Version)
Forget the traditional four seasons. San Francisco has its own rhythm.
- Spring (March–May): This is the windiest time. The temperature hovers around 60-65°F. You’ll get clear blue skies, but the gusts coming off the bay will cut right through a light sweater.
- The "Gray" Months (June–August): This is the peak of the marine layer. Expect a lot of "High: 66, Low: 54" days. It’s consistent, gray, and damp.
- The Peak (September–October): The real summer. The warmest temperatures of the year, often hitting the mid-70s or even 80s if a heatwave hits the coast.
- The Wet Season (November–February): Most of the city's 20+ inches of rain falls now. Temperatures stay between 45 and 58 degrees. It rarely freezes, but you'll feel like you can't get dry.
The Role of Karl the Fog
You can't talk about the temperature of San Francisco without mentioning Karl. Yes, the fog has a name. Karl is a sentient-acting wall of mist that determines your wardrobe for the day.
When Karl is in town, the "feels like" temperature drops instantly. The fog isn't just clouds; it's moving moisture. It carries the chill of the North Pacific. If you see a white wall creeping over the Twin Peaks, you have about fifteen minutes before the temperature drops by 8 degrees.
Surviving the San Francisco Climate
If you’re visiting, or even if you just moved here, you have to change how you think about clothes.
- Layers are a religion. You need a base layer (t-shirt), a thermal layer (flannel or light sweater), and a wind-resistant outer shell.
- Forget umbrellas. The wind in SF usually moves sideways. An umbrella will just turn into a broken piece of modern art within three blocks. Get a hooded raincoat.
- Cotton is the enemy. Once cotton gets damp from the fog, it stays cold. Wool or synthetics are much better for staying comfortable when the marine layer settles in.
- Check the sensors. Don't just look at the Apple Weather app. Use something like Weather Underground to look at specific neighborhood stations. The "San Francisco" forecast might say 70, but "Ocean Beach" might say 58.
The Long-Term Trend
Is it getting hotter? Sort of.
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While San Francisco remains one of the most temperate cities in the US, we are seeing more extreme "heat events." In 2017, the city hit an all-time record of 106°F. This was catastrophic because most San Francisco homes—especially the beautiful old Victorians—do not have air conditioning. When the temperature of San Francisco spikes like that, the city feels like an oven because the infrastructure is designed to trap heat, not vent it.
These spikes are rare, though. The vast majority of the time, the city remains a cool, breezy anomaly in a state that is otherwise baking.
Actionable Takeaways for Navigating the Chill
To master the San Francisco climate, you need to act like a local. Stop checking the "High" for the day and start checking the wind speed and the humidity levels.
- Always carry a "just in case" layer. Even if it’s 75 degrees at noon, it will be 55 by 6 PM.
- Head East for warmth. If the fog is ruining your day at the Golden Gate Bridge, hop in an Uber and head to Dolores Park in the Mission. It’s almost guaranteed to be five to ten degrees warmer.
- Watch the hills. The hills act as a physical barrier. Neighborhoods "behind" the hills (on the eastern slope) are shielded from the direct Pacific wind and are consistently the most comfortable places to hang out.
- Visit in October. If you want the quintessential California experience without the shivering, book your trip for the first two weeks of October.
The temperature of San Francisco isn't a number; it’s a mood. It's a shifting, living thing that requires you to be prepared for three seasons in a single afternoon. Embrace the chill, buy the overpriced hoodie, and remember that the fog is just part of the city's charm.