An extreme holiday heatwave will hit Perth over Christmas, with the city a chance of setting a new national record for the hottest Christmas Day in an Australian capital city.

A mass of hot air will be drawn over southwestern Australia over the coming days as a high pressure system passing to the south of the state drives warm continental air towards a West Coast Trough.

This weather setup is notorious for generating heatwaves in Perth at this time of year, and this one will certainly live up to its reputation.

Image: A tongue of heat will extend across western districts of WA on Christmas Day.

Temperatures are forecast to reach around 38ºC today (Christmas Eve), before rocketing to 42 or 43ºC on Christmas Day and Boxing Day. Overnight minimums will only dip to the high-twenties on Saturday and Sunday nights, before another two days with maximums hitting the low-forties or high-thirties on Monday and Tuesday next week.

This run of heat will be intense enough to qualify as an Extreme heatwave on the Australian scale. These heatwaves are rare and can cause problems for anyone that doesn’t take precautions to keep cool, including people that are otherwise healthy.

The timing of this heatwave may also see Perth set a new record.

Australia has only ever seen 42ºC reached at one of its official capital city weather stations twice on Christmas Day. These were 42.0ºC at Perth Regional Office in 1968 and 42.1ºC at Adelaide’s West Terrace weather station in 1888.

There is a good chance that Perth will warm past these historic holiday figures and set a new record.

It should also be the first time an Australian capital city has exceeded 41ºC on both Christmas Day and Boxing Day.