Perth has recorded its earliest 40 degree December day on record.

Temperatures soared throughout the day, with Pearce topping 42.2 degrees Celsius at about 1:45pm.

The Perth weather station recorded 41.6 degrees at 12:10pm.

Temperatures remain in the high 30s this afternoon, with night time temperatures will bring little relief.

The hot weather is being caused by trough in the north of State is travelling south along the coast bringing with it very hot air.

Minimum temperatures are not expected to drop below 20 until Sunday.

Tomorrow is forecast to be 36 degrees and another 40 degree day is forecast for Friday.

It comes after the city melted through November, which broke monthly records for above average daytime temperatures across WA.

The bureau’s outlook between December to February nationally has predicted a drier and hotter than average summer, elevating the risks of bushfires and heatwaves.

Perth forecast:

Wednesday: 22C-36C, mostly sunny.

Thursday: 22C-38C, very hot and sunny.

Friday: 24C-40C, very hot and partly cloudy.

Saturday: 20C-28C, partly cloudy.

Sunday: 17C-30C, mostly sunny.

Monday: 18C-33C, sunny.