The Big Bash doesn't have a specific heat policy, but umpires have been told to offer extra drinks to the players if necessary.

Early predictions suggest temperatures at Penrith's Howell Oval could reach 36 degrees on Saturday afternoon. Similar conditions hovered over last season's WBBL final during which Sixers star Ashleigh Gardner was forced from the ground with heatstroke.

"To be honest I was trying not to check the temperature for the last couple of days because I was scared," the Thunder's New Zealand import Rachel Priest said.

"The heat's always been a little bit of a struggle for me, being from New Zealand, I'm not used to that sort of heat. We've had three fairly hot games so far, so I'm acclimatising pretty well and today's been pretty hot.

"It's just about looking after yourself well and recovering right after the game as well."

A win over the Stars will take the Thunder to the top of the WBBL table after four games, and the western Sydney outfit will be buoyed after their eight-wicket triumph against the same opponent in Albury on Tuesday.

Priest and fellow opener Rachael Haynes combined for an 86-wicket opening stand in that match, setting Sydney on the way to chasing down the 115 runs required for victory.

Haynes, who captained Australia as they retained the Ashes against England, is the third-highest run scorer already this season with 126, behind Gardner and Suzie Bates who have both blasted centuries.

"Hopefully she'll repeat what she did the other day as well," Priest said of her opening partner.

"She's a quality player and I think we work pretty well together. We're just looking to have good partnerships and set the team up.

"I was probably a little bit shaky at the start but I was happy to get some runs in Albury, albeit a little bit scratchy to begin with. I felt like I got a couple away pretty well. I'll be hoping to keep contributing at the top of the order."

The Stars have struggled so far this competition, losing both of their games in the post Meg Lanning-era. Their former captain, last year's leading WBBL run scorer, signed a three-year deal with the Perth Scorchers three months ago, but will miss the entire summer as she recovers from shoulder surgery.

"It's a home game for us and we'll be looking to replicate what we did that other day against them," Priest said.

"Hopefully we'll have a little bit of a mental edge. It's familiar territory, we've talked about our plans the other day and they obviously worked quite well, we'll have a little bit of a go over that.

"In this competition you can't take anyone lightly and they would've gone away and done a bit more research on us."