Driving north on I-5, just past Yreka, you see them. The Siskiyous. They aren't just hills; they are a massive, jagged wall of rock that decides whether your road trip is a scenic dream or a white-knuckle nightmare.
Most people think "mountain weather" is a simple matter of cold versus hot. In this range, it’s never that linear. The weather for the Siskiyous is a chaotic cocktail of Pacific moisture hitting a wall and "dirty" high-pressure ridges that trap fog in the valleys while the peaks bake in unseasonable sun.
Right now, in mid-January 2026, we’re seeing exactly how weird this place gets. While much of the country is shivering, the Siskiyous are currently sitting in a strange, dry bubble. If you’re at the summit today, January 17, it’s actually kind of pleasant—sunny with a high of 58°F. But don't let that fool you. By next weekend, the forecast is shifting toward rain and snow, with overnight lows dipping back toward freezing.
The "Wall" Effect: Why the Siskiyous Are Different
The Siskiyou Mountains are part of the Klamath knot, a geological mess that doesn't follow the rules of the Cascades or the Sierras. Because they sit so close to the Pacific, they act like a giant sponge.
Moisture travels in from the coast and gets shoved upward. This is orographic lift, and it’s why the western canyons can see over 100 inches of rain while the eastern slopes, like those near the Shasta Valley, get barely 20.
You’ve probably heard of the "rain shadow." In the Siskiyous, that shadow is more like a blackout.
It’s the reason why the Rogue River-Siskiyou National Forest is a temperate rainforest on one side and an arid, juniper-dotted landscape just forty miles east. Honestly, the biological diversity here is mind-blowing because of these microclimates. You’ve got foxtail pines that usually live in the Sierras rubbing shoulders with Engelmann spruce from the Cascades.
📖 Related: Marcus Hook SEPTA Train Station: What Most People Get Wrong About This Delaware County Hub
Current Conditions and the Immediate Forecast
As of early morning Saturday, January 17, 2026, the current temperature in the mountains is a crisp 42°F, feeling more like 37°F with the 8 mph east wind. It’s clear tonight, but the pattern is changing.
- Today (Saturday): High of 58°F. Sunny skies will give way to a cloudy night.
- Sunday: Staying relatively warm with a high of 57°F, though we’ll see more clouds.
- The Big Shift: By January 24, the "dirty" ridge finally breaks. Expect the high to drop to 50°F with a 20% chance of snow overnight.
The Interstate 5 Factor: Surviving the Summit
If you're a trucker or just someone trying to get home, the only weather that matters is at the Siskiyou Summit. At 4,310 feet, it’s the highest point on the entire I-5 from Mexico to Canada.
It’s not just the snow that gets you. It’s the fog.
The Oregon Department of Transportation (ODOT) frequently warns about "hazardous visibility" between October and April. This isn't just a light mist; it’s thick, "socked-in" soup that makes the 6% downgrade feel like you’re driving off the edge of the world.
Statistically, about half of the accidents on this stretch involve commercial trucks. That’s why the chain-up areas are so strictly enforced. If you hit the inspection site at Milepost 1 or 11 and you aren't carrying iron, you’re getting turned around. No exceptions.
The 2026 Snow Drought and the La Niña Flop
We need to talk about the "snow drought" everyone is whispering about at the local diners in Ashland and Yreka.
📖 Related: Wisconsin Dells Resorts Water Parks: What Most People Get Wrong
This winter was supposed to be a La Niña year. Usually, that means "cold and wet" for the Pacific Northwest. But 2026 has been stubborn. A persistent high-pressure ridge has been acting like a shield, pushing the storm track further north or south.
While Mt. Ashland usually boasts an average snowfall of more than 265 inches, this season has been sluggish. We’re seeing a transition to ENSO-neutral conditions—basically the "meh" of weather patterns—expected by March.
What does that mean for you?
It means the "natural reservoir" is at risk. Up to 75% of the region's water supply depends on that snowmelt. Without a big late-season dump in February, the summer fire season could be brutal.
Looking Ahead: The Late January Turn
The Old Farmer’s Almanac and the National Weather Service are actually in agreement for once: late January 2026 is going to turn "chilly."
The rainy periods are expected to return in earnest between January 19 and 23. We’re looking at a transition toward wetter-than-average conditions. If you’ve been waiting for the "real" winter to start, it’s finally knocking on the door.
💡 You might also like: The Church of St. John the Divine NYC: Why This Massive Unfinished Cathedral Still Matters
Practical Next Steps for Travelers and Locals:
- Check the Cams: Before you even put your shoes on, check TripCheck.com for the Oregon side and the Caltrans QuickMap for the California side. Cameras don't lie.
- Pack the Essentials: Even if it’s 59°F on Monday, keep the chains, a heavy blanket, and extra water in the car. The Siskiyous are famous for "surprise" squalls that the radar misses.
- Timing the Pass: Mid-day is statistically the safest time to cross the summit. Temperatures are at their peak, and the morning "slick" has usually burned off.
- Watch the Ridge: If you see "patchy valley fog" in the forecast for Redding or Medford, expect the mountains to be unseasonably warm due to the inversion. It’s a great time for a hike, but a terrible time for valley air quality.