I had a similar problem....

turns out the gas cap has a TINY hole in the top to allow air to enter
the gas tank so the gas can leave. With all that snow flying around it
is easy for some snow to fall in the hole, freeze and clog it shut.

I drilled 4 somewhat larger holes in the side of the cap and it seems
to have fixed it for me. (With the cap off and clean of gas, don't
bring your electric drill near a gas tank please....)

I don't think you can have a vapor lock problem when it is 25 deg F
out.