'Respect the heat': Extreme weather in Victoria's north keeps the fire risk high

Emergency authorities have urged Victorians to stay alert to the risk of fires over coming days and to the health risks from extreme heat, as temperatures remain at dangerous levels in northern Victoria but ease in Melbourne.

CFA chief officer Steve Warrington said that with extreme temperatures over coming days, fire authorities would be on "high alert", with a major focus on high risk areas.

At a briefing on Thursday afternoon, Mr Warrington said there had been 40 fires across Victoria on Thursday, mostly grassfires.

All had been "aggressively" attacked by fire crews and kept small, he said.