How can I make sure my rabbit stays warm tonight?

IMO, I don't think that is enough to keep him warm. 10ºF is 22º below freezing, at that temperature your rabbit may die from hypothermia. I would keep him inside for the winter. there are some rabbits made to live outside. but this one is your pet. and If I were you I would keep him indoors for the time being.

Line the floor with layers of newspaper and add lots of extra hay and straw for your rabbit to bury itself into.Blankets and fleeces are also useful for them to snuggle into or to line the floor with. Buy some cheap carpet samples for them to sit on (make sure the edges aren't fraying). Get a cardboard box, close all 4 sides and cut a hole big enough for your rabbits to get through, and fill the box with hay. This will give them somewhere a bit more insulated to sit. Buy them a 'Snugglesafe Heatpad'. You warm it up in the microwave and it releases heat for a few hours, so you'll need to reheat it a couple of times a day. This is actually a good idea, but obviously it doesn't continue releasing heat for a long amount of time.

If you put a tarp or blanket on the outside, kept the light bulb on, added some newspaper/ blankets to the inside along with some extra hay, then your rabbit should be good on really cold nights. If possible, you could also move the hutch to a garage or shed. Now what about water? If you have a normal water bowl in the hutch, the water is going to freeze. You probably need a heated water bowl, if you don't already have one.

Hope this helps!

What I do is put a cloth over the cage, that really keeps them warm . Trust me I have been raising rabbits for 7 years and they never dye in the winter. and yes that will keep em warm :)

I would keep the rabbit indoors during the winter. Just to be safe. :)