Bureau of Meteorology senior forecaster Dean Stewart said Saturday will kick off with sunshine and the temperature climb to 28 degrees.

"[But] there is likely to be showers and thunderstorms developing this afternoon around the Melbourne area," Mr Stewart said.

"It is possible anytime after midday, but it is more likely from 3pm onwards."

He said the thunderstorm could bring shower, rain and hail.

"We have got very humid air across the state and a weak trough but with low pressure lying across the state which helps to trigger off the thunderstorm activity," he said.

"If the thunderstorm goes right on top of you, we could get intense rainfall, possibly hail and gusty winds,"

Mr Stewart said Sunday would be more of the same with a top of 25 degrees. 

Yesterday, thunderstorms hit north-west of Melbourne, showering Sunbury and Macedon with hailstones. But the severe weather warning did not bring much damage to the state.

State Emergency Service spokesman Stefan Delatovic said the emergency service received 20 call outs overnight from Friday 9pm to Saturday 7am.

"The callouts were from across the state, predominantly trees being blown down, and there were couple of minor building damage jobs," Mr Delatovic said.

"There was a reports of some sheets of iron coming lose in the wind in Swan Hill."

Mr Delatovic said there were 160 SES units across the state prepared for any possiblity.

"Our arrangements are based on the fact that the weather is unpredictable," he said.

"A lot of the time we will issue a warning and nothing will happen, but when it does happen, it happens very quickly."

Powercor is reporting four power outages across Victoria, two of them due to lightning strikes.

Banyena in the Wimmera region, and Kenley in Swan Hill were without power due to a lightning strike. Both were expected to be restored by 9.30am.

Powercor spokeswoman Avi Tan said there was also a power outage for more than one hour in Brunswick on Friday night due to a possum.

"There was a possum on one of our power lines . It caused a trip in the circuit breaker from 9.20pm for about an hour and 45 minutes," she said.

"Power was back by 11.05pm."

The SES has advised people in storm-affected areas to keep clear of fallen power lines, secure any loose objects and stay indoors.

Residents have also been advised to avoid using the phone during storms, and to switch off computers and electrical appliances.

Those caught outside should avoid sheltering under trees.

SES has urged people in affected areas to listen to the radio for storm updates.