Honestly, looking at the sky in San Mateo right now, you wouldn't necessarily guess we’re in the thick of a California winter. We just came off a wild start to the month—remember that brief tornado warning back on the 5th? Yeah, that was a trip. But as of today, Sunday, January 18, 2026, things have settled into that classic, slightly confusing Peninsula groove where you need a puffer jacket at 7 AM and sunglasses by noon.
If you’re checking the 10 day forecast san mateo ca to plan your week, you’re basically looking at a stretch of "is it actually winter?" weather.
Today is sitting pretty at a high of 64°F. It’s partly sunny, mostly calm, and frankly, a great day for a walk down by Seal Point Park. But don’t let the sun fool you; the overnight lows are still dipping into the 40s.
The Mid-January Shift: Sunshine and Chill
Most people assume January in the Bay Area is just one long rainstorm. Not this year. We’ve got a weak La Niña playing around with the jet stream, which usually means things stay a bit drier and cooler than the historical average.
The immediate outlook for San Mateo is remarkably stable.
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Monday, January 19, looks even clearer with a high of 63°F and a low of 45°F. It’s the kind of day where the air feels crisp but the sun has some real bite to it.
Things start to cloud over as we hit Tuesday and Wednesday. Expect the highs to drop slightly to around 60°F or 61°F. It won't be "cold" in the East Coast sense, but with 72% humidity and a north wind, that damp Peninsula chill is going to settle into your bones if you aren't layered up.
10 Day Forecast San Mateo CA: The Breakdown
Planning out the next week and a half is actually pretty straightforward for once. We aren't seeing any major atmospheric rivers aiming for us—at least not in the immediate future.
- Sunday (Today): 64°F / 47°F. Partly sunny. Wind is barely a whisper from the southwest.
- Monday (MLK Day): 63°F / 45°F. Mostly sunny. It’s probably the best day of the week for outdoor plans.
- Tuesday - Wednesday: Highs near 60°F. Cloudy. Expect that "gray veil" to hang over the city.
- Thursday - Friday: We stay in the low 60s. Partly sunny skies return.
- Next Weekend: Saturday and Sunday (Jan 24-25) look like carbon copies of each other. Highs of 60°F, lows around 48°F.
The "what most people get wrong" part? Thinking this dry spell will last. While the next 7 to 8 days look clear, the long-range models are sniffing out some light rain moving in toward Wednesday, January 28.
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Why San Mateo Weather is Weird Right Now
San Mateo sits in a unique spot. We’ve got the Santa Cruz Mountains to the west and the Bay to the east. This creates a little microclimate pocket that often misses the worst of the coastal fog but catches the wind coming off the water.
Right now, the dew point is hovering around 46°F. That’s dry for us. Usually, our January humidity makes everything feel slightly soggy, but this week is unusually "crisp."
If you're a gardener, keep an eye on those nighttime lows. While we aren't seeing 30s in the current 10 day forecast san mateo ca, the 45°F forecasted for Monday night is close enough to be a concern for some of your more sensitive tropicals if a rogue cold patch hits.
Prepping for the Week Ahead
So, how do you handle a forecast that’s mostly 60 and cloudy?
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- Layers are non-negotiable. A high of 64°F feels like 70°F in the sun and 55°F in the shade.
- Watch the wind. Even a 3 mph wind off the Bay (like we have today) carries a lot of moisture.
- Plan your car wash. Honestly, with only a 5% to 10% chance of rain through next Monday, your car will stay clean for at least a week.
- UV Awareness. People forget the sun exists in January. The UV index is low (around 2), but if you’re out on the water or hiking the Pulgas Ridge, you can still get a bit of a burn over a few hours.
The real shift happens toward the end of the month. The Almanac and NWS are both pointing to a "stormier" period hitting in late January. While the current 10-day window shows only a 35% chance of light rain by the 28th, those numbers usually trend upward as the systems get closer to the coast.
Basically, enjoy the dry pavement while it lasts. San Mateo is beautiful when the air is this clear, and 64°F in January is a gift you shouldn't waste.
Next Steps for San Mateo Residents:
- Check your tire pressure; these 20-degree temperature swings between day and night can trigger your TPMS sensors.
- Clean out your gutters now while it's dry, before the late-month rain systems arrive.
- Schedule any outdoor home repairs for the early part of this week (Monday through Wednesday) to take advantage of the stable conditions.