Haynes believes a perfect blend of young stars and experienced recruits like English duo Heather Knight and Tammy Beaumont, and star quick Sammy-Jo Johnson have meshed into a side capable of winning this season's WBBL title.

The Thunder clash with Johnson's old team, the reigning champion Brisbane Heat, in a blockbuster semi-final in Sydney on Thursday. For so many of the Thunder's young stars, it'll be their first taste of finals cricket.

"They've done really well across the whole tournament so this game is no different, it's just about trusting your skills and executing those, not getting too far ahead of yourself in the match," Haynes said.

"It's pretty exciting, we saw glimpses of what they were capable of last year, players like Hannah Darling, Phoebe Litchfield, Anika Learoyd. They've just continued to grow, continued to develop and we've seen their performance under pressure too.

"Sometimes it's a little bit challenging leading a younger team, sometimes they can do things that are amazing, and then other times things happen and I wonder why that happened.

"That's probably been the big difference this year we're closing that gap between our very best, and perhaps the other point of the spectrum where things don't go quite as well.

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"It's been really nice to see our team develop, see different people stand up in different moments."

Wins over Adelaide and Hobart over the weekend earned the Thunder a shot against Brisbane, which is eyeing a third straight title.

"They've been a really successful club the last couple of years, they've dominated this competition," Haynes said.