Cafes will close early, sporting events have been called off and extra measures put in place to protect vulnerable people today as Perth prepares for one of its hottest ever spells.
With the mercury tipped to hit a scorching 44C by 3pm, water and electricity utilities are also getting ready for demand to soar as householders desperately look to escape the heat.
The Water Corporation acknowledged yesterday that Perth's long-standing record for water use in one day - 1.35 billion litres on January 31, 1991 - could even be broken.
Cinemas and shopping centres, meanwhile, are also expecting a surge in demand as people flock to air-conditioned refuges.
It came as WA's top firefighting agency said it would have extra crews on stand-by today amid catastrophic fire conditions and the Health Department said it would also put on more staff.
All over Perth sporting events have been cancelled or modified in anticipation of the heat.
Cricket Australia said the second day's play of the women's Ashes Test at the WACA Ground was due to go ahead as planned but extra drinks breaks were likely to be granted to the players.
Some events, such as junior athletics meets in Karrinyup and Joondalup, have been cancelled, while preparations have been made to call off others.
In Perth's south-east, about 1100 competitors had been expected to take part the City of Armadale's triathlon but the council warned it could be stopped if temperatures became a problem for competitors.
The Weather Bureau said the severe temperatures were being caused by a high pressure system south-east of the State and a trough to its west, the combination of which was funnelling hot, dry winds over WA's South West.
The last time the temperature in Perth reached more than 43C was on Boxing Day 2007.
Department of Fire and Emergency Service deputy commissioner Lloyd Bailey said the forecast conditions would be particularly challenging.
As he noted a total fire ban would be in place across parts of the State, Mr Bailey said preparations centred on the highest risk areas including the Pilbara, the Perth Hills and the South West.
Health Department State health co-ordinator Revle Bangor-Jones said emergency departments were "well aware" of the need for extra staff and would prepare for a surge in heat- related presentations.
The Water Corporation said demand would be highest in the morning as people "back washed" their pools and put their washing on, while it would also surge in the evening as they watered their gardens.
Western Power said electricity use was expected to be higher than normal but it would be "business as usual" for the network operator.
At Perth Zoo and the Dogs' Refuge Home in Shenton Park, ice blocks, regular showers, extra shade and air-conditioning will be provided to animals to give them relief.
The WA Maritime Museum said submarine tours today and tomorrow had been cancelled.