PEOPLE living on Melbourne's fringes need a reality check about fire danger, authorities say.

A 2400ha fire caused traffic gridlock and prompted evacuations across the city's northern suburbs yesterday.

Fire Services Commissioner Craig Lapsley said many residents did not have a fire plan.

He said it was a worrying sign, given that much of outer Melbourne is prone to such fires.

"Grassland fires are a reality and continues to be a reality in the landscape that we're living in," Mr Lapsley said.

"We're not trying to scare communities. We're just trying to give them a reality factor."

The fire was thought to have destroyed a home in Epping North but CFA crews assessing damage in the area found three sheds had burned.

One of the sheds may have been used as a dwelling but it wasn't a house, authorities said.

Several more sheds are thought to have been lost, but no homes.

Cooler conditions and light rain today reduced the threat posed by the grassfire.

The fire, which has now been contained, is burning near a number of outer northern suburbs including Donnybrook, Epping and Campbellfield.