Full sun all day long. Last August my pool temperature low was 95 and the high was 101. So far this year I've been up to 95 but the last week it's been in the high 80's/low 90's. Sometimes I use an umbrella for some shade, and I have two fountains coming out of the wall that spray. I run my pump at night with fountains to cool. I put up with it though because I can swim from April to October, normally. Trade-offs. And 95 degrees still feels good after I mow the lawn!