My cold weather PR is -29 degrees F. That's the coldest temperature where I was living at the time. I hit it twice, first in Madison, WI in 1/97 and again last winter here in Timmins. I check temperatures a lot when it gets in the extreme range, hot or cold.
This week the record may be shattered. Low temp predictions are for around -35 on Wed. and TH. There's not much you can do when it's that cold. Locals, here in Timmins, might moan a little but they take it in stride...no local sympathy. Obviously there's no running outdoors (it's always windy here as well), so the treadmill will be in full use. And a week ago I was running outdoors in the California sun.
Tomorrow I go to the doc's and get more feedback on what's up. Running on the treadmill seems so my easier on my legs, so the cold won't affect my running. I'm just going 3-5 easy miles/day right now, hoping to get a little stronger.