Victoria is under a total fire ban on Thursday as temperatures top 40C in the state's north, while thunderstorm asthma could also put lives at risk.
Victorians facing Code Red bushfire conditions have been told their houses are not built to withstand the conditions and they should get to major cities if they can.
Temperatures are forecast to stay well over 40C in the state's north, and strong northerly winds have put the Mallee and the Northern Country districts on a Code Red alert.
Conditions will be milder in the rest of the state, but fire danger ratings are listed as severe or very high, while temperatures are close to all-time November highs, with Melbourne forecast at 39C on Thursday.
A total fire ban has been issued statewide, but the worst conditions are in the state's north.
Code Red signals the worst possible bushfire conditions and the safest place to be is away from high-risk fire areas within those districts, the CFA advised.