Honestly, if you’ve ever spent more than twenty minutes standing outside near the airport, you know the vibe. South San Francisco isn't just "San Francisco's neighbor." It’s its own beast. People always assume the weather here is a carbon copy of the Mission District or the Sunset, but they’re usually dead wrong.
Right now, as of Friday, January 16, 2026, we are sitting in a weirdly calm pocket of winter. It is 5:59 AM, and the current temperature is 52°F. The sky is clear with periodic clouds, which is basically the "industrial chic" version of a sunset. Humidity is high at 80%, and a light 6 mph breeze is coming in from the northeast.
Basically, it's hoodie weather. But don't get too comfortable.
The Microclimate Reality Check
The "Industrial City" sits in a geographical funnel. While San Francisco proper gets hit by "Karl the Fog" coming through the Golden Gate, South San Francisco deals with the marine layer squeezing through the San Bruno Gap. This gap is a low point in the Santa Cruz Mountains that acts like a wind tunnel for cold Pacific air.
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Today, Friday, January 16, the high is hitting 63°F with a low of 51°F. It’s sunny, which is a nice break from the massive storms we saw earlier this month. Remember those king tides on January 2nd? Streets were literally underwater. We’re past that for now, but the "thermal belting" the National Weather Service is talking about is real. You’ve got warm air sitting in the hills while the cold air is trapped down here in the flats near the biotech campuses.
What’s Coming This Week
If you're planning your weekend, Saturday, January 17 is looking mostly cloudy with a high of 63°F. There’s a tiny 10% chance of rain, which is basically just the sky threatening you without following through.
Here is how the next few days are shaping up:
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- Sunday, January 18: Mostly sunny, high of 62°F. Perfect for a hike up San Bruno Mountain, though the wind will probably be a bit nippy.
- Monday, January 19: Sunny with a high of 62°F. A classic crisp winter day.
- Tuesday, January 20: Mostly sunny, cooling down slightly to 60°F.
- Wednesday, January 21: We start seeing a shift. Partly sunny with a high of 58°F as that ridge over the Gulf of Alaska finally gives up.
The wind has been mostly coming from the northeast lately, which is why things feel a bit drier and "mild." But by next Thursday, the onshore flow starts creeping back. That means more coastal clouds and the potential for actual rain by the end of the month.
Why the Wind Matters
You’ve probably noticed that South City wind. It’s relentless. Unlike the swirling winds in the city, the wind here is a focused, northwesterly push. It’s why the trees on the ridge are all permanently leaning to one side.
The National Weather Service recently recorded an 850 mb sounding that was near a record high temperature of 16.6°C. That sounds technical, but what it means for you is that the atmosphere is basically "upside down" right now. The hills are warmer than the valleys. If you’re at Oyster Point, you’re feeling that 52°F chill, but if you drive up to the top of the "South San Francisco" sign hill, it might be ten degrees warmer.
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Surviving the South City Winter
Don't trust the sun. It’s a liar. You’ll see a clear blue sky, walk out in a t-shirt, and get blasted by a 7 mph northeast wind that feels like ice.
- Check the gap. If you see clouds pouring over the mountains toward the airport, the "fog finger" is coming. Your temperature will drop 10 degrees in 15 minutes.
- Layer up. This isn't advice; it's a survival strategy. You need a windbreaker that actually breaks wind, not just a thin cotton sweater.
- Watch the tides. If we get another storm like the one on January 4th, the low-lying areas near the bay front are the first to flood.
The rest of January looks like it’s going to stay dry until about the 22nd. After that, the models are leaning toward "wetter than normal" conditions. Enjoy the sunny 60-degree days while they last, because the end of the month looks like it’s going to bring the rain back in a big way.
Keep an eye on the wind direction. When it flips from northeast to southwest, that's your cue that the dry spell is over. For now, just appreciate the fact that you don't need a kayak to get to work.
Actionable Next Steps:
Check your tire pressure if you’re commuting via US-101; these 20-degree temperature swings between day and night can cause your sensors to go haywire. If you’re planning outdoor work, aim for Monday morning when the sky is clearest and the wind is at its most predictable 7 mph from the northeast.