Answer:

It's Australia Day. There are fireworks all over the place:

Perth Skyworks, on the river between the CBD and South Perth (8 pm). (Simulcast on MIX 94.5 FM)

Indian Ocean Skyshow, at Bathers Beach Fremantle (8 pm). (Simulcast on 6IX, 1080 AM or 405.7 FM)

Town of Bassendean Australia Day Celebrations, at Ashfield Reserve (8 pm). (Simulcast on 98.5 Sonshine FM)

City of Armadale Australia Day Fireworks at the Armadale Council Carpark (8.30 pm). (No simulcast love for Armadale.)