too hot for infant ?!

Shirley • Love*life*family*goals
So we don't have an AC & are staying temporarily at a family's home and they don't want an ac in the house.. I'm worried that when the baby comes home it'll be to hot for him. We're on the second floor and it's an old house.. it's uncomfortably hot for myself. Are infants okay with 80-90 degree weather ? I guess back in the day they were okay so maybe I shouldn't over think it ?