Hard to see in pic but many inches of ice in bottom of creek. Waders filled up, had to strip to my long underwear top and fished all day. Funny, didn’t notice cold while GL’ers where grumbling and looking like Marshmallows. I’ve had my oil gel up in basement tank and spent too many -10 to -30 degree nights trying to get furnace relit every few hours.
Then I fish the Glen in May, temps drop after a bit of rain and my hands almost didn’t function to unlock the car. Had pain I’ve rarely felt from cold before. Sometimes it just hits you. Others you can hike out in snow with a rifle in 20-30 mph winds and -30 temps and it just feels a bit brisk.
I’d be leery of using a heater suit. Sweat kills and so does cotton. Tricks like loosening or half lacing boots to let air circulate and blood flow are helpful. Merino sock liners to pull away sweat. Have to regulate or you sweat then freeze.