About 10,000 customers in the city’s north have no electricity this afternoon, and about 8,000 in the city’s east.
Power companies say they have called in extra crews to speed up repairs.
Weeks of dry weather combined with dust and light rain sparked a series of power pole fires last night.
Up to 50,000 customers had been affected by the initial power outages.
Jemena supplies customers in Melbourne’s north and this morning they had more than 11,500 households or businesses without supply.
Essendon, Moonee Ponds and Pascoe Vale were among the suburbs affected.
United Energy said more than 12,000 customers in Melbourne’s east and south-east were without power, including in Cheltenham, Oakleigh and Doncaster.
“Our crews have been working right across the night and into the morning and they’ll continue to do so all day to try to get [power back] as soon as possible,” said the company’s Stuart Allott.
Powercor was also working to re-connect customers in Melbourne’s west, including in Sunshine and Werribee Laverton.
Trains on the Cranbourne and Pakenham lines faced delays of up to 20 minutes due to the problem, and some railway boom gates were affected.
Police also urged drivers to take care on the roads, with some traffic lights not working.
The Metropolitan Fire Board (MFB) says it received more than 50 calls about the fires overnight.