Multiple Geelong V/Line services have been stopped as a large fire burns at Little River, with firefighters battling to control the fast-moving blaze.
The grass fire is travelling in a south-easterly direction towards Manor Road, Emergency Victoria said in a statement.
A Watch and Act message has replaced an evacuation notice for Mambourin and Manor.
Firefighters have been able to stop the spread of the fire, but the fire remains active within fire boundaries.
Residents have been told that leaving now is the safest option, and that conditions can worsen rapidly.
Motorists have been told to avoid travelling on the Princes Freeway unless necessary as a result of the smoke, VicRoads has said.
Train services on the Geelong line have been suspended between Geelong and Wyndham Vale, with road coaches ordered.
Major delays are expected, V/Line has said.
Advice warnings have also been issued for Werribee, Avalon, Cocoroc, Point Wilson, Werribee South, Brophys Crossing, Tarneit, and Wyndham Vale.
There is currently no threat to you, but you should stay informed and monitor conditions the Advice warnings read.
Video captured by the chopper camera shows a shed being engulfed in fire, as black smoke pours from the structure.
Two relief centres for people affected by the fire have been set up. One is located at Centenary Hall, on the corner of Cox and Melbourne roads, Norlane, while the other is at Wyndham Encore Events Centre on Derrimut Road in Hoppers Crossing.
Large amounts of flames and smoke are issuing from the blaze, which can be seen from Avalon Airport, located about 25 kilometres away.
Firefighters, along with several helicopters and fixed-wing aircraft, are working to control the grass fire.
The fire comes as a Watch and Act alert remains for a bushfire in Buninyong, near Ballarat in Victoria’s west.
A Total Fire Ban is in place today amid sweltering temperatures and strong winds
Some relief from the heat will arrive in Melbourne overnight as a weak change moves through, but temperatures won’t drop into the low-20s until late tomorrow morning.
A maximum of 26 degrees is forecast, ahead of a much cooler top of 22 degrees on Sunday.
Not all parts of Victoria will welcome the cooler temperatures, with northern parts of the state expected to remain hot right through the weekend.