Ours are out in their run at present but we're checking them every 30 minutes or so. We use an old polycotton shower curtain to cover the run, making sure that only about 1/3 of the run is not covered because Pineapple does like to sunbathe. We peg the shower curtain down with clothes pegs but otherwise leave it loose like a tent so the breeze can get under and into it.
The curtain doesn't cover all of the run but we make sure that the south facing side is well covered and the east or west side depending on the time of day.