The storm was fast, hard and furious and left a blanket of ice across residential properties in Metford, Thornton, Ashtonfield and East Maitland.

The Bureau of Meteorology had barely extended the reach of its severe weather warning to the Hunter Region when the first hailstones hit.

"I was at Maitland at the doctors and I walked outside and said 'have a look at that'," Ashtonfield resident Michael Edmunds said.

"When I got home I heard a loud bang and then the hail came down.

"It was just a little at first, but then they were the size of golf-balls."

Mr Edmunds was one of many residents in the area who experienced damage to their house roofs and cars as the hailstorm swept through the city in the space of about 30 minutes.

The State Emergency Service received more than 20 calls in an hour, with reports of leaking and broken roofs and skylights.

While the hailstorm smothered many suburbs others, including Maitland CBD, south Maitland and further afield at Dungog, missed the onslaught.

"There is an intense region of cold air from the upper level atmosphere," Weatherwatch's Anthony Cornelius said.

"When this cools rapidly, 10 or 12 degrees in 24 hours, we get this upper low and the weather you have experienced.

"That's why yesterday it was picture perfect and today [Thursday], not so much."

According to the latest data from the Bureau of Meteorology, the storm was the start of a week of showers across the Hunter, with temperatures expected to reach maximums of 17 to 24 degrees.

The team at Weatherwatch agreed with the forecast.

"There is a broad upper trough and south east winds coming in the next week," Mr Cornelius said.

"There will be showers on the coast, but for the Maitland area there will be a few showers mixed with fine weather."

For emergency help in floods and storms, ring the SES on 132 500.

Warnings are also available on the Bureau of Meteorology's website at www.bom.gov.au or call 1300 659 218.