Beaches along the coast have been closed due to lightning.
Quinns, Mullaloo and Sorrento beaches were closed about midday as a storm front rolled in.
Hillarys, Trigg, Floreat, City and North Cottesloe beaches were closed about 12.30pm.
Quinns, Mullaloo and Trigg beaches has now been re-opened
Temperatures reached 36C at about 11.40am today but dropped into the low twenties within an hour.
Thunderstorms and showers are expected to continue throughout the afternoon and into the evening.
This morning Surf Life Savings reported that a tagged white shark was detected at the Ocean Reef receiver at 6.49am.
A surfer reported a 2-2.5m shark about 300-400s south of the surf club at Secret Harbour.
The Westpac Rescue Helicopter sighted a 3m shark 200m north of Catherine Bay, Rottnest.
Tagged white shark was also detected at Garden Island North at 12.49pm.