Honestly, if you're looking at the sylmar weather 10 day outlook right now, you’re probably seeing a lot of sun and thinking it’s basically summer. It’s January 15, 2026, and while the rest of the country is reportedly bracing for an "Arctic revenge" that could freeze iguanas in Florida, Sylmar is sitting pretty with a high of 78°F today.
But here’s the thing about this pocket of the San Fernando Valley: the numbers on your screen only tell half the story.
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Sylmar is a weird, beautiful microclimate. It’s tucked right against the San Gabriel Mountains, and that geography does wild things to the air. You’ve got the Santa Ana winds potentially kicking up, the "high desert" influence, and a temperature swing that will make you question every outfit choice you’ve ever made.
The Immediate 10-Day Breakdown
Today, Thursday, started off crisp but it’s hitting that 78°F peak under perfectly sunny skies. If you’re out at Veterans Park or hiking Wilson Canyon, it feels amazing. But don't let the 4 mph breeze fool you. Tonight, it’s dropping to 58°F. That’s a 20-degree dive.
Tomorrow, Friday the 16th, keeps the heat at 77°F. Then the weekend hits. Saturday and Sunday (Jan 17-18) are hovering right around 75°F.
Wait, check the wind.
Forecasts show northeast winds jumping to 16 mph by Friday. That’s the Santa Ana influence. It dries everything out. Your skin will feel it, your plants will feel it, and if you’re a local, you know this is "fire weather" territory even in the dead of winter.
By the time we get to next Thursday, Jan 22, the "winter" part of January finally remembers to show up. We’re looking at a high of 68°F. Still "California cold," sure, but the overnight lows will start dipping into the 47°F range.
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Why the Valley "Lie" Happens
Most people look at a Los Angeles forecast and assume it applies to Sylmar. Big mistake. Huge.
Because Sylmar is at a higher elevation than, say, Van Nuys or Northridge, it catches the first breath of the mountain air. In the summer, that makes it a furnace. In the winter, it creates these massive "diurnal shifts."
I’ve seen days where it’s 80 degrees at 2 PM and you’re literally scraping frost off your windshield at 6 AM the next morning. It’s a crapshoot. You have to pack for two different planets every single day.
The Humidity Factor
Right now, the humidity is sitting at a bone-dry 33%.
By next week, it’s expected to climb toward 50% as the sun hides behind some "partly sunny" clouds. When the humidity is low, the heat doesn't stick to you, but the cold bites harder. When it’s high, that 67°F on Friday the 23rd is going to feel a lot dampier and chillier than the 78°F we have today.
What to Actually Do With This Info
If you’re planning your week around the sylmar weather 10 day trends, here is the ground-level advice:
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- Hydrate like it’s July. These northeast winds and 20% humidity levels will dehydrate you before you even feel thirsty.
- The "Three-Layer" Rule. Morning: Heavy hoodie. Noon: T-shirt. 5 PM: Back in the hoodie, maybe a windbreaker.
- Garden Alert. If you’ve got sensitive plants, the dip to 47°F next Thursday is the "danger zone."
Basically, enjoy the next four days of "fake summer." It’s the best part of living in the Valley. Just keep an eye on those wind speeds—16 mph is enough to knock over a patio umbrella or stir up enough dust to ruin a car wash.
Keep your eyes on the clouds toward the end of the month. While the "chance of rain" stays low (mostly 0-10% in the current forecast), January is historically a flip-the-script month for SoCal. For now, it's nothing but blue skies and sunscreen.
Next Steps for You: Check your tire pressure tonight; these big temperature swings usually trigger those pesky "low pressure" sensors. Also, if you’re planning a hike at O’Melveny Park this weekend, aim for before 11 AM to beat the direct UV peak, which is hitting a moderate level 3 despite the "winter" date.