Powercor is reporting about 100,000 customers are without power owing to unplanned outages caused by the storm. The areas with the most properties without power include Geelong and the Surf Coast, Ballarat, Maryborough and the western suburbs of Melbourne.

The energy provider said a combination of extreme temperatures, strong winds and thousands of lightning strikes caused damage to poles, wires and other electrical infrastructure.

Powercorp powerlines went down in Browns Road in Werribee on Tuesday afternoon, which was affecting homes in the area.

Metro Train advised people to defer travel in Melbourne due to reports of storm damage across the network. Passengers were advised to consider alternative transport options if possible on Tuesday afternoon.

Buses are replacing trains on several lines due to the storm damage. Metro services are impacted on sections of the Belgrave, Craigieburn, Cranbourne, Frankston, Glen Waverley, and Pakenham lines, as well as V/Line services on sections of the Gippsland, Seymour and Shepparton lines.

Replacement buses were expected to be delayed in their arrival on Tuesday afternoon, a spokesperson said.

The Bureau of Meteorology warned severe thunderstorms detected near Caulfield, Melbourne city and Cranbourne were forecast to affect Berwick, Clayton, Dandenong and Pakenham on Tuesday afternoon.

Meteorologist Kevin Parkyn said severe thunderstorms with the potential for damaging winds were expected to continue for several hours into Tuesday evening.

“The situation is very dynamic,” Parkyn said.

“Our colleagues from the State Emergency Service have been very busy responding to requests for assistance for trees and other damage associated with the strong winds.

“We got the situation as we predicted last night and this morning of fires burning in the western part of the state but also storms and storm damage affecting areas closer to Melbourne,” he said.

Emergency Management Commissioner Rick Nugent said lightning had started a number of fires across the state, particularly in the west, which were threatening homes.

“We have seen a very challenging day today, with very, very hot, windy and dry conditions across the state,” he said.

“We’re seeing significant hail in a number of areas, with very, very strong winds to such a degree that they’ve even brought down some powerlines.”

A catastrophic fire rating was issued for the Wimmera for Tuesday and Melbourne and the western half of the state are under a total fire ban.

A severe thunderstorm warning was issued for Ballarat, Geelong and Melbourne. Damaging winds are also forecast, with a 130km/h gust recorded at Mount Gellibrand, between Colac and Winchelsea, at 11.35am.

A road weather alert was issued for Melbourne on Tuesday afternoon and Avalon Airport recorded a wind gust of 122 km/h about 2.20pm.

CFA chief officer Jason Heffernan warned those in high-risk bushfire areas that the safest option was to evacuate before hot and windy conditions hit.

West Wimmera Mayor Tim Meyer told 3AW on Tuesday morning that schools and kindergartens had shut, which annoyed some residents.

Thunderstorms are forecast to move across the state in the afternoon, possibly exacerbating the dangerous fire weather with lightning strikes and gusty winds.

In the Mallee, the weather bureau predicts “raised dust” could hit Mildura, Kerang, Ouyen and Birchip in the afternoon, potentially causing blinding dust storms. All of these towns are expected to reach at least 39 degrees.

In the Wimmera, Horsham is expected to hit 37 degrees and Warracknabeal may reach 39 degrees. Northerly winds are forecast to become south-westerly and reach 55km/h in the early afternoon.

Emergency management commissioner Rick Nugent said aircraft had been deployed to high-risk areas.

A severe thunderstorm could hit Melbourne after a sunny morning. The predicted maximum is 37 degrees, after not dipping below 20 degrees overnight.

The heatwave that began on Saturday is expected to peter out on Wednesday, when the maximum temperature is predicted to fall to 19 degrees.

A catastrophic fire warning was last issued during the Black Summer bushfires in the summer of 2019-20, when 33 people died, 3000 homes were destroyed and more than 17 million hectares of land were burnt.

Heffernan, the CFA chief, told 3AW on Tuesday morning that Victoria had yet to experience any significant rainfall in February after wet weather hit the state earlier this summer.

With Hannah Kennelly