” I should have said “gear selection failure”
Don’t know the North Cascades (too far to drive), but if the weather is both cold and wet, or hypothermic, even the best gear can be a problem. But there is no reason to add to it by thrashing through heavy bushes, branches and other flora, as mentioned above. Plan to hike in an area with cleared and maintained trails below timberline.
After getting wet with jackets that were junk, waited for a sale and got a Patagonia pullover that was pretty good; but putting on and taking off a pullover in a downpour is not a dry exercise. So after hunting for a couple years, found a $350 M-10 jacket for under $200 on sale. It has never let me down, even in combo hike/paddle trips, sitting in a kayak in the pouring rain all day.
Also key is a good GTX bucket hat under the jacket hood, so you can see where you’re going. For my lower half, just wear ‘baggies,’ a form of short bathing suit. Then GTX gaiters were worn over the sox and mids to keep the water out.
When it gets colder, but still rainy, a grid fleece sweater goes under the jacket, and a fleece watchcap under the hat. With all that, I’ve never gotten hypothermic; but have seen many hikers who did, and it can be a killer. So it may be best to stop early and get into a tent, as was already suggested.
And that raises the need for a tent that pitches dry inside and stays that way with a dry entry and exit, and a double wall and good ventilation to avoid condensation, which can destroy heat retention. We now have silpoly, so there is no need to deal with a sodden tent. There are more and more silpoly tents coming on the market, so pick a good one. And no need to spend gazillions for a DCF tent whose durability is problematic. Like some of the above posters, the tent must also be spacious because much time may be spent in it, especially in the East, where it can rain for days on end.
Should mention that some folks overheat easily; but I take it easy and am lucky to remain dry. So there is hope, but a lot of care and preparation does have to go into it. Good luck!