Temps will be the hottest of the week, 97 degrees forecast high - so on court it will probably be something insane like 115-120 with the sun beating down. Definitely something to consider for the matches played during the day. See the projected temp at 90 by 11am. These temps are 15-20 degrees higher than earlier this week.
Rod Laver matches should be played under the roof I would imagine. Would be ridiculous not to. Shari already posted how hot it felt yesterday when it was only about 80 I think ... so it's going to be a large factor for some of these players.