I cant think of a single reason tho close it all summer unless theres a big storm.
Old attic windows opening.
It gets stifling and stale up there if we don t.
The windows have screens.
When the attic becomes part of the home to be heated and cooled open wall gable vents and roof vents are no longer feasible but the underside of the roof the sheathing and rafters can still.
2 are ornamental and the other 4 are regular functioning windows.
During the summer and most of fall we keep 2 windows open for cross ventilation.
A broken window glass of the attic room of a house with the red shingles roof.
We do get bugs flies in the summer ladybugs in the fall.
The attic needs to be as close to the outside temp as you can get it year round.
6 windows in all.
Attic glass open window in an old wooden house with meander ornament.
We have a large full attic.
Thoughtful young woman looking at camera from the window of an attic at sunset.
If you leave the attic windows open be sure and staple some screens over them maybe even hardware cloth would be better to keep the critters out bats and raccoons etc will invade your space and give you fits.
If so you should keep the windows open both winter and summer.
And if necessary i d keep them open just a crack until you can get some roof vents in place or gable vents.
You should open the window in late spring and close it in early fall.