Breakdown of Okkur var kalt úti en það hlýnar núna.
vera
to be
en
but
það
it / there (existential) / the one (n)
úti
outside
Questions & Answers about Okkur var kalt úti en það hlýnar núna.
Why is the sentence "Okkur var kalt" instead of "Við vorum köld"?
In Icelandic, feelings of temperature use an impersonal structure. Instead of saying "We were cold" (Við vorum köld, which would mean your personalities are cold or your bodies are literally cold to the touch), you say "To us was cold." The person experiencing the temperature is put in the dative case, which is why we use okkur (to us) instead of við (we).
Since "okkur" means "we", why is the verb "var" (was) singular instead of plural?
Because okkur is in the dative case, it isn't the grammatical subject of the sentence. In impersonal constructions like this, the verb always defaults to the 3rd-person singular form, which is var in the past tense.
Why is "kalt" in the neuter singular form here?
Just like the verb, the adjective in an impersonal sentence doesn't have a normal subject to agree with. When there is no nominative subject, adjectives always default to their neuter singular form. So even though okkur refers to multiple people, we use the neuter singular kalt.
Why does the second half use "það hlýnar" instead of "okkur er heitt"?
Okkur er heitt means "We are feeling hot." However, the sentence means the weather or environment is warming up. Það hlýnar uses the dummy subject það (it) and the verb hlýna (to get warmer), similar to how English says "It is raining."