"Fueron unos días calurosos."
Translation:They were some hot days.
This translation makes no sense to me, sorry. 'They were hot days' or 'There were some hot days' we would say in English.
Sounds fine to me. Do you have a problem with the singular as well? It was a hot day.
with exactly the same construction previously the translation was 'They were cold days'.
A previous answer to a translation question was "They weren't cold days," so I would expect that "They were hot days," would also be correct.