Thunderstorm hits Adelaide after thousands of homes left without power by overnight lightning

Hours after thousands of homes were left without power overnight, Adelaide has again been lashed by rain, hail and storms, as intense downpours moved across the city and hills.

The Bureau of Meteorology (BOM) said "two main cells" developed suddenly this afternoon, dumping rain across parts of the metropolitan area.

A severe thunderstorm warning, for damaging winds and large hailstones, was earlier issued for the Adelaide region, but has since been cancelled.

But there were widespread reports of heavy rain and hail from north and south of the city, and in parts of the Adelaide Hills including Mount Barker.

"It's really amazing. I'm sitting in the car and there's about a centimetre of hail across the ground," one listener told ABC Radio Adelaide's Jules Schiller after driving through Hawthorndene.

"Some of it's easily three centimetres."

Another caller in Adelaide's west said there "lakes all over the place".

"It was bucketing and the sun was shining the whole time, got into Kilkenny and you could spin the gutters for redfin, there's that much water."

One person in Adelaide's south said she was in a shopping centre when water began "flooding out of their light fittings".

"[Water was coming out] their electrical air-conditioning units and drenching people up and down on the escalators so people were getting absolutely soaked," the caller said.

Senior forecaster Mark Anolak said a band of thunderstorms "from the northern parts of Adelaide right down to the southern suburbs" had developed "very quickly".

"We knew the atmosphere was conducive to thunderstorm development — we knew it was going to be quite explosive when it did happen," he said.

"Later this evening we could still hear a rumble of thunder but for the most part the worst of it will have past."

Early this morning, about 10,000 South Australian properties were without power following severe storms overnight.

The weather bureau said about 65,000 lightning strikes were recorded in the 24 hours to 5am.

The first band of bad weather hit the state about 9:30pm last night, followed by another between 3am and 4am.

The storm activity woke many South Australians, with people taking to social media to share their experiences of the "deafening" sounds.

Mr Anolak said rainfall varied from about 4 millimetres at Noarlunga, in Adelaide's south, to 25 millimetres at nearby Marion, while 20 millimetres were recorded over half an hour at the airport this morning.

Earlier today, the State Emergency Service (SES) said it had not yet received any reports of significant damage.

The SES said it had received more than 20 calls for help since midnight, including from Redwood Park, where a branch fell on parked cars.

However, it expected the number of calls to increase as people woke up to damage.

SA Power Networks also expects more reports of power outages.

Paul Roberts from the network said current outages were "widespread" and lightning strikes were likely to blame for many of the issues.

In two of the larger outages, about 2,700 properties were affected at Mannum and 1,000 at Andrews Farm — but power in both areas has since been restored.

"Most of the outages are smaller outages," Mr Roberts said.

Meanwhile, South Australian Human Services Minister Nat Cook has urged people sleeping rough to find shelter, with wet weather forecast for the remainder of the week.

Ms Cook said a code blue has been issued, which meant extra support services were available for people sleeping rough, including more options to find shelter.

"We would encourage people to reach out to get assistance rather than leave themselves subjected to the elements, which are going to be quite severe until Friday morning," she said.