It seems like there are always fireworks going off in Perth*. This blog answers the question: 'Why tonight?'.
*Perth, Western Australia.
Answer:
Around 7.30 in Swanbourne it's the Westside Wolves' Club Day, while in Claremont (at the park on Stirling Road) it's a private function (how mysterious).
Around 8.45 near the Kiosk Floreat Beach, it's another private function (how mysterious).