A couple of the coldest I remember were in the eighties:

Once we had sub-freezing temps for a week, but when the Artic blast finally started to break a friend decided he couldn’t wait any longer to take his new DB out for the first time. So off we go to drop in at Plum’s on the Sno. There's a bit of ice at the ramp but it's still very dark and to way too cold to sit around, so we shove off anyway. Right off the bat he's having trouble with his oars, so he drops anchor to check things out. Next thing we hear banging on the back end off the boat and as the light comes up we realize the river is chock full of patio-block sized icebergs moving downriver. I have never seen anything like it, before or since, on our rivers in the NW. We figured it must have been pool ice that was braking up coming over the falls. Man, I’d heard of ice fishing but this was ludicrous. Anyway there was no way to get a line through that stuff to fish, so we just floated out to Fall City, thankful it wasn't a more technical drift with all that ice.

Let this other time be a warning to all that like to hike in to fish on cold snowy days:

There was too much snow at Palmer Kanasket SP to drive down to the river so I hoofed in from the top. About 12” of snow or more as I recall. Beautiful, sunny, but very cold day with just enough mountain wind to keep everyone else away. First thing, I hook a nice fish in the deep pool and bank it. As I go to hang it in a tree, it kicks off and quickly slides back into the water. Good news is I grab the fish, bad news is I go into the pool after it and fill my boots with ice cold water. In total denial, I empty my boots and keep on fishing. But in minutes I’m getting really cold so I decide to call it quits and head back. Big problem. My wet felt soles turn the snow to ice and pack up quickly on the bottoms, making it very difficult to walk in the waders without stopping every 10 yards to chip the ice off my soles. But the worst part is that the water in my boots is quickly turning to ice and freezing my feet. So before I’m 100’ from the river I have to turn back to stand in the river just to unthaw my feet. So now I’m standing in the water, fish in hand, trying to figure out what my next move is going to be while the situation goes from bad to worse. Realizing the gravity of the situation, I suck it up and make the excruciating hike up the hill and back to the car over a 1/2 mile away. How I made it back I’m still not really sure but I do know I was one cold, wet, scared, hurting and lucky dude that day.

The things we’ll do and go through for a steelhead.