Heatwave warning for Victorians

Victoria's unseasonably hot March has continued with record temperatures reached on Tuesday.

Melbourne city hit 38.9C, its hottest March day since 2008, says Bureau of Meteorology duty forecaster Rod Dickson.

And Moorabbin hit 40.8C, its hottest March day on record, he said.

There is not expected to be much relief through the night, with a minimum of 26C forecast for Melbourne.

Mr Dickson said temperatures in the 30s were forecast again across most of the state on Wednesday, with showers and thunderstorms developing.

Victoria's Department of Health issued a heat health alert on Tuesday evening after the boiling temperatures led to three people being admitted to hospital after fainting at Port Melbourne.

All three were in a stable condition.

The health department warned people to drink plenty of water, not to leave people or animals in cars, seek air-conditioning and plan ahead to keep out of the heat.

Ambulance Victoria's state health commander, Paul Holman, also warned people to adjust their activities to "respect the heat".

"It's the overnight temperatures that are going to cause us grief, as people don't recover from the heat and that's when they start to get into trouble," he told reporters.

Wednesday is a very high fire danger for all regions apart from the South West.

Cooler conditions are forecast over the weekend but Victorians should not expect a large drop in temperature - it is still anticipated to reach the high 20s next week.