Perth sweltered through near record-breaking heat overnight, with the minimum only dipping to 27.3C.
The mercury reached 37.3C at 2.35pm yesterday and only dropped below 30C about 7pm.
Last night’s minimum overnight temperature was just .5C below the 27.8C record for January, which was recorded in 1989.
Weather Bureau duty forecaster Peter Clegg said it had been particularly humid in Perth over the past few days because of ex-tropical cyclone Narelle coming down the coast.
“Tonight could still be a little but muggy because we are not really expecting that cool change to come through until the early hours of tomorrow morning,” he said.
“It could still be quite warm for the early parts of tonight and then easing off a bit tomorrow.”
A partly cloudy and humid day is expected today, with a maximum temperature of 36C.
At 5am, the mercury had already reached 30.1C.
On Wednesday and Thursday the temperature is only expected to reach a maximum of 26C before it creeps back up to 29C and over for the rest of the week.
The bureau is warning of severe thunderstorms south of a line from Augusta to Manjimup to Albany.
The thunderstorms could bring destructive winds, large hail and heavy rainfall which may lead to flash flooding,
Storms may cause significant damage to homes and property.
Manjimup recorded 19mm of rain in 30 minutes to 7am and there have been reports of localised tree damage from wind gusts near Capel.