The Bureau of Meteorology is forecasting a heat wave to hit Perth over the coming days.
The barometer reached 39.6 degrees at the Bureau's Mount Lawley recording station on Christmas Day, with other parts of Perth hitting 40 degrees.
Senior Forecaster Matt Boterhoven says it was the fifth hottest Christmas on record.
He says Perth temperatures are expected to stay in the very high 30s and early 40s until New Year's Day, with a maximum of 41 degrees expected both days this weekend.
"Over the next six days or so we're expecting temperatures in the Perth metropolitan area to be above 38 degrees as a maximum temperature," he said.
"When we have a maximum temperature of 35 degrees or more for three days in a row, we consider that a heatwave.
"It's quite unusual to see 40 degrees forecast for four days in a row."
Some respite is expected to arrive on New Year's Day with a forecast maximum temperature of around 34 degrees.
© ABC 2012
00:33 EDT Severe thunderstorms and damaging winds caused chaos across Sydney on Sunday, with the SES responding to more than 550 jobs, mainly roof damage from heavy rain and strong winds.