Before air conditioning became accessible, large window fans (like the Homart Cooler - which I own) were very popular in the middle of the country with hot days

Before air conditioning became accessible, large window fans (like the Homart Cooler - which I own) were very popular in the middle of the country with hot days and cool night (e.g. St Louis). Not as good as placing one in the attic, but a really effective alternative that can be carried from property to property.