While southeastern Australia braces for a blast of wintry weather later this week, sothwestern Australia is getting an early taste of summer.

A high pressure system moving to the south of WA this week is directing a stream of warm inland air towards the state's South West Land Division.

Image: Forecast surface temperature and wind speed/direction according to the ECMWF model.

Perth reached 26 degrees on Wednesday, which is six above average for this time of year. On Thursday, the city is forecast to reach 30 degrees, which would be its warmest day in five months.

While this week's heat will be a noticeable change from the cooler weather of the last few months, it's not going to break records. Perth's warmest September day on record was 34.2 degrees in 2014.