Group A winners India will take on England in the first of the two semifinals at the Sydney Cricket Ground with match commencing at 09:30 GMT.
Rain is forecast for Sydney on Thursday and no reserve day is in place for the matches. If the semifinals are washed out due to rain, the group winners - India and South Africa - would progress to Sunday's final at the Melbourne Cricket Ground, meaning England and hosts Australia would be eliminated.
England's 2017 World Cup winner Alex Hartley told Test Match Special it is "mindblowing" there is no reserve day.
"Rain happens, even in Australia!" Hartley said.
"I'd rather have the chance of playing - it's an hour's flight to Melbourne from Sydney.
"It's not like they're asking players to fly halfway round the world.
"India and South Africa have played the most consistent cricket so they do deserve to be top of the group but it is mindblowing there's no reserve day,"
Organisers are hoping to set a new record for the highest attendance for a women's sporting event for the final and further tickets have gone on sale with more than than 50,000 already sold.
The current record is 90,185, set at the 1999 football World Cup final between USA and China at the Rose Bowl in California.