Christmas Day is set to be a scorcher in Perth, with temperatures expected to reach 37 degrees Celsius.
Less than a week ago, the Bureau of Meteorology predicted Christmas Day would rise to a maximum of 31 degrees Celsius, but the changing position of the surface trough along the west coast has caused the forecast temperature to jump by six degrees.
The city today recorded its second straight day of 40C, surpassing the mark at midday, as residents prepared to celebrate Christmas.
Bureau of Meteorology Duty Forecaster Darryl Vink said a moderate afternoon sea breeze — the "Fremantle Doctor" — should still help to cool Perth down a little.
"[After] a top of 40C today, it will be slightly cooler tomorrow as the surface trough moves inland, going into late morning and into the afternoon," Mr Vink said.
Today’s hot weather is expected to continue through the night, with the minimum projected to be around 22C, before the temperature heats up again for Christmas Day.
"It could be another night for the air conditioner," Mr Vink said.
Train delays expected
WA's Public Transport Authority (PTA) has warned of possible delays on train services today due to high temperatures, with a forecast of 40C expected.
PTA spokesman David Hynes said trains were slowed by 10 kilometres an hour when temperatures reached 39C and another 10 when it got to 41C.
Mr Hynes said while the train tracks were well-preserved, extra measures needed to be taken when the temperatures rose.
"We peel a bit of speed off the train, simply because the track being metal can distort slightly in the heat," he said.
"So, to give it a smoother ride, we take 10 kilometres off it."
Perth forecast
The Bureau of Meteorology said temperatures across Perth would be cooling down slightly for the weekend.
Boxing Day this Saturday is expected to reach a top of 35C with a strong, fresh sea breeze and Sunday is set with a top of 33C.
- Thursday: Min 24C, max 40C
- Friday: 22C-37C
- Saturday: 21C-35C
- Sunday: 15C-33C
- Monday: 14C-34C
- Tuesday: 21C-35C
- Wednesday: 20C-35C
Mr Vink said the hot temperatures meant people should be careful when they were outside.
"Slip, slop, slap and stay out of the sun as best you can," he said.
