Would this jacket keep me warm in sub-zero temperatures? Could I survive a Vermont winter in this?

The higher the fill power the more insulating air pockets the down has and the better insulating ability. 800 downfill is very typical to be used in sub zero sleeping bags as well as non sub zero sleeping bags. The material on the outside also helps up the warmth of the coat.

Since this is just rip-stop nylon with water repellent. If it gets wet then the down insulation will not work as well.

I wore my 800 fill down coat in sub freezing levels this winter and it kept me warm. On those windy or wet cold days, I used a shell over it to help block any wind or water from getting in the down. The length on the jacket hits on the upper hips. So if you need something to keep your hips and butt warm, this won't do it.

Make sure when you wash this to get a down wash detergent, like "nikwax". Use a front loading washer and fluff it dry in the dryer and make sure it is dry all the way through so the feathers to do not stick together and destroy those pockets for insulation.
View Details: The North Face Catalyst Summit Series Down Jacket - Women's >