When it's about 30degrees here. We live in a top floor unit and we get full sun all day and we have big double glass doors on both sides of the house so it's full sun, from sun up to sun set, and it gets really hot up here. I can feel the heat increase as I come up the stairs! When the sun goes down I usually turn it off and open the big double glass doors to catch the breeze. Cuase we are up the top, we can catch even the slightest breezes.