A couple years ago, we had a hellaciously cold day, and school was cancelled statewide. The actual air temp was something like 31 below, and the windchill pushed it to 52 below. I brewed a batch in my garage - an AG Munich Helles. I called it "Helles Frozen Over". Indoor mash, water bath for propane, indoor chill by the utility sink. It was great!
Final tip - You GOTTA hit up some grilled cheese sammies with tomato soup for lunch!