Flights in and out of Melbourne Airport were delayed as lightning struck across the city, with reports of hail in some areas.

State Emergency Service spokesman Lachlan Quick said there had been 130 calls for help between noon Thursday and 6am Friday, mostly concentrated in outer northern metropolitan areas of Mernda, South Morang and Sunbury.

Mr Quick said Sunbury was the hardest hit, with 30 calls including for hail damage. The rain and hail caused the roof of the Foodworks supermarket in Evans Street to collapse. In Melbourne, the Epping police station was closed because of damage from flash flooding.

Rain fell in two bands, Mr Quick said, and the second caused flash flooding in Mernda and South Morang. Much of the damage to homes occurred when gutters filled, forcing water onto roofs.

Trees also fell but there were no reports of power lines down.

Bureau of Meteorology senior forecaster Dean Stewart said 66 millimetres of rain fell in Mernda, with 38mm in Sunbury and 45mm at Christmas Hills, in the outer-east.

Melbourne can expect showers and the chance of thunderstorms on Friday, with a top of 31. Saturday may be the only dry day for the next week: the bureau has forecast a partly cloudy day, with a top of 33. On Sunday, showers are expected, and they are tipped to continue until at least Thursday.

Mr Stewart said while much of Melbourne had seen storm activity, there was no rain for the city and many suburbs.

He said that into next week, the humid atmosphere would continue, and conditions would be quite unstable into early next week.