If you’re planning to drive up to the intersection of Highway 89 and Highway 299, you’ve probably heard about the trout. Hat Creek is basically hallowed ground for fly fishermen. But honestly, the hat creek ca weather is the one thing that can turn a "dream trip" into a "why am I shivering in a tent" nightmare.
It’s a high-desert-meets-alpine-volcanic-valley situation. Most people assume Northern California means mild. They are wrong.
Right now, as of January 16, 2026, it is 29°F in Hat Creek. It's sunny, but don't let that fool you. The humidity is sitting at 58% and the wind is a lazy 2 mph coming from the south. The high for today is expected to hit 55°F, but tonight it's going right back down to 23°F. That's a 30-degree swing in a single day.
The Volcanic Reality of Temperature Swings
Hat Creek sits in the shadow of Mount Lassen. It’s a spring-fed system, which means the water temperature stays a chilly, consistent 50-ish degrees. But the air? The air does whatever it wants.
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In July, you’ll see highs hitting 90°F or even 91°F. You’re sweating through your waders by noon. Then the sun dips behind the Rim, and by 10 PM, you’re looking for a fleece because it’s dropped to 47°F.
Basically, the "dog days" here aren't just hot; they're bipolar. If you're hiking the Hat Creek Rim—a notorious stretch of the PCT—you’ve gotta carry more water than you think is reasonable. It's an arid, shadeless basalt landscape that radiates heat like an oven. In late summer, the ground temperature can be significantly higher than the air temperature reported on your phone.
Why Winter is Actually Kind of a Secret
Most folks pack it up by November. They shouldn't.
January weather here is actually quite manageable if you're prepared. Looking at the forecast for the next week:
- Saturday, Jan 17: Sunny with a high of 58°F and a low of 24°F.
- Sunday, Jan 18: Mostly cloudy, high of 56°F, low of 19°F.
- Monday, Jan 19: Sunny again, 57°F high, 21°F low.
There's a 10% chance of snow on Sunday and Monday, which is pretty typical for this time of year. Hat Creek gets about 20 to 24 inches of snow annually. It’s not a winter wonderland like Tahoe, but it gets enough to make the technical "Carbon Flats" section of the creek look like a postcard.
Fishing the Hat: The Weather-Hatch Connection
If you’re here for the fishing, the weather is the hatch.
The bugs are picky. May and June are prime because the temperatures are "comfortable"—meaning highs in the 69°F to 78°F range. This is when the Salmonflies and Green Drakes show up.
But here’s the pro tip: watch for the overcast days in October. While the average high is 67°F, a sudden storm front changes the barometric pressure and triggers the Blue-Winged Olive (BWO) hatches. The fish go nuts. Even when it starts to snow in late November, the BWOs keep coming. If you can handle a 26°F low, you can have the best fishing of your life with zero crowds.
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Survival Tips for the Hat Creek Microclimate
Don't trust a single-day forecast.
- Layer like an onion. You need a base layer for the 20-degree mornings, a sun shirt for the 60-degree afternoons, and a windbreaker for the breezy gusts that hit 11-13 mph in December and January.
- The "Rim" Warning. If you are hiking the Hat Creek Rim in May or June, it’s beautiful. Wildflowers everywhere. If you do it in August, it's a 40-mile dry stretch. The "strenuous" rating isn't about the climb; it's about the 91°F heat and the lack of shade.
- Check the UV. Even when it’s 29°F out, the sun at this elevation (around 3,400 feet) is intense. Today’s UV index is a 2, but in July, it’ll bake you.
The hat creek ca weather is defined by its extremes. It's a place where you can get a sunburn and frostbite in the same 24-hour window if you aren't paying attention.
To make the most of your trip, aim for the "shoulder" months. Late May or early October give you that sweet spot where the highs are in the 70s and the lows stay above freezing. But honestly, even a cold January day like today is worth it for the clarity of the water and the silence of the valley.
Before you head out, double-check the wind direction. A north wind in Hat Creek usually brings a chill that bites through even the best Gore-Tex. Today's south wind at 2 mph is a gift—take advantage of it.
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Pack a heavy sleeping bag, bring a wide-brimmed hat, and always keep a rain jacket in the truck. You'll thank me when that 10% chance of snow turns into a reality at 4 PM.