Health authorities are warning people to take care and commuters can expect a longer commute as Victoria sweats through a late summer hot spell.
The Bureau of Meteorology says a heatwave will sweep across most of Victoria for the rest of the week with stuffy overnight temperatures on Friday and Saturday.
The Chief Health Officer has issued a heat health alert for the central district for Thursday to Saturday based on the forecast.
An alert has also been issued for the South West District on Friday and North Central is approaching the threshold for its own warning.
"Extreme heat can affect anyone. Pregnant women, people with a pre-existing medical condition, people aged over 65 and children and babies are most at risk," the warning reads.
Emergency Management Victoria has also warned about the increased fire risk across the state.
Fire danger ratings are mostly high and very high for Thursday and Friday and are likely to increase to severe in some areas on Saturday.
Emergency Management Commissioner Andrew Crisp warned while there had been mild temperatures this summer, there had not been a lot of rain and the state was extremely dry.
"With temperatures peaking to 40 degrees in parts of the state on Saturday, people should prepare and keep up to date with their local weather conditions and plan essential activities for the coolest part of the day," Mr Crisp said.
"Stay hydrated and check in on others - particularly those most at risk in the heat such as the elderly, the young, people with a medical condition and don't forget your pets."
Yarra Trams has also issued service changes for routes 12, 30, 78 and 82 due to the heat.
Australian Associated Press