While eastern Australia focuses on an impending outbreak of rain and thunderstorms, parts of the nation's north and west are busy trying to beat the heat.

The temperature in Darwin only dropped to a low of 30.0 degrees during Tuesday night and Wednesday morning, which is the city's highest minimum temperature on record. This high low temperature beats the previous record of 29.7 degrees, which has occurred six times since 1941.

Meanwhile, daytime temperatures are set to climb in Perth over the next 48 hours, with the city a chance to register its highest temperature in nine months on Friday.

Warm air will flow from central WA towards Perth as a high pressure system passes to the south of the state on Thursday and Friday. The mercury is forecast to exceed 30 degrees each day between Thursday and Saturday, reaching a peak of 38 degrees on Friday.

The mercury hasn't reached 38 degrees in Perth since March and if it gets there, it will be nine degrees above average for this time of year.

Darwin is forecast to be a few degrees cooler from tonight and Perth's maximum temperatures will drop following a wind change on Saturday.