When I took this photo it was -33c. So I kind of wonder how there was frost on anything. You see you need it to be moist in the air for that and frost tends to happen near the freezing point. Well it's way too cold to be that humid out there. But here is how it happens... It's the same as frost on the windows of the car in the morning when it's freaking cold out. The car heats up when you use it and when the sun shins on it all day and the snow melts from that. This causes a bit of moisture to hang onto the paint. So when it cools off after you park it the frost comes up from that moisture you did not even see when you parked it.
What I really hated in my older cars (mostly happened with Fords) is when the inside of the window frosted up. This was from the moisture in your breath mostly. See some of the newer cars have air filters that will actually take the moisture out of the air. This is a good thing and prevents the inside frost from happening. After all nothing sucks worse when it's -35c and you need to scrape the inside of the window then the dash gets wet when the car heats up...
It looks all kinds of trailer trash, but if you put a blanket over the windshield then close it in the doors, the window often does not frost up. There are also sprays you can get to prevent the window from frosting up - but most of them don't work well and you are spending good money there to save not so much work.
One time I read a FB post that said to put gliserin on the window. Well that would make it harder to see out the window proper like. Sigh. But there was also the recommendation from the same person to spray 1 part vinegar to 2 parts water on the windows to de-ice them. Well kiss your paint goodbye if you are stupid enough to do this. Sigh.
The thing is, the stuff that prevents icing tends to be a bit expensive and so on. But it's a good idea to keep a squirt bottle of deicer in the car in case the locks to your house freeze up (it happens). It might not help and you might still be stuck in the cold calling for a pro to help - but it may help and get you inside quicker.