But a freak gust of wind nearly turned it into an unthinkable tragedy for one Bowral family.

Farther-of-two Stuart Bollom will never forget the image of an inflatable jumping castle being ripped from the ground and carried 150 metres with his two children inside.

Seven-year-old Daniel and baby sister Emma were spat out of the cartwheeling castle and driven into the ground.

Daniel is still nursing a broken left arm and broken nose while little Emma has snapped her collarbone.

And the horror scene which followed is one the family is still reliving.

"In that half a second I realised it was my kids, my heart just dropped," Mr Bollom said.

"But you don't really have time to think, I just started running after it, I was on auto pilot.

"It was horrible when I saw the kids because blood was pouring out everywhere and Daniel was saying 'I'm dying, I'm dying'."

Bowral Police and WorkCover are investigating how the Police and Citizens Youth Club castle came to topple over so easily.

And young Daniel and Emma have already told their parents that they won't be frolicking on a jumping castle ever again.

"Daniel's already told me that he won't be going on one again," Mr Bollom said. "But really we're all fairly relieved now because it could have been a lot worse.

"We're not angry at anyone, we just want to warn others to take extra care when they're setting up these types of activities.

"The kids are obviously pretty shaken up by it but the bones will heal."

The family also wanted to thank emergency crews and all the other guests that helped them in the wake of the accident.

"We really want to extend our thanks to all the people that were there at the time," Mr Bollom said.

Council general manager David McGowan said he had reviewed the situation to prevent a similar accident happening in future and had also spoken to the family.