So am I right in thinking that adjectives require 'van' in impersonal constructions? So to say 'it's cold' you can't just say 'hideg', it has to be 'hideg van'?
Would it be appropriate to use definite articles here as it sounds like a general statement?
For which word?
Both. For "Decemberben" and "januárban". I was thinking "A decemberben és a januárban hideg van?".