Thank you.
Yes, it's vital. The only functional way to deal with an emergency response related to fire is to have the equipment ready. A fire truck has water in it and you can't leave it outside, especially in Arctic temperatures. Without water, it's not going to serve you. Fundamentally, it needs to be indoors and heated, and it needs to be plugged in. That's typical of all fire apparatus across this country.
I hope that helps you.