Hot tropical air from a cyclone forming off the coast of Darwin is expected to spread to south-eastern parts of the country this weekend, nudging temperatures into the 30s.

The warm weather has been triggered by the combination of a strong high pressure system moving east from WA, and a tropical low north-west of Darwin, which is likely to form into a tropical cyclone this weekend, Weatherzone reports.

Melbourne is forecast to reach 30 degrees tomorrow and could hit 32 degrees in some areas on Sunday.

The warm weather in Victoria will remain in the high 20s throughout the week.

The mercury will soar to 34 degrees in Adelaide on both tomorrow and Sunday, and will remain in the 30s until Thursday, sitting well above the maximum April average of 22.2 degrees.

Minimum temperatures are also expected to sit six to eight degrees above the average across the weekend in both cities.

The low pressure system is expected to develop into a Category 1 tropical cyclone tomorrow and could strengthen to Category 2 by Sunday evening as it tracks in a southwesterly direction, close to the Kimberley coastline, according to Weatherzone.

It could develop into a severe tropical cyclone next week, but early indications suggest it is unlikely to cross the WA coast.

Damaging winds and heavy rain could however lash the Kimberley coastline this weekend and early next week as a result of the system.