One man is dead and another girl is in hospital after a severe thunderstorm and strong winds caused flooding and blackouts across Adelaide.

The 39-year-old man died after he was struck by lightning in Mount Barker about 2.30pm on Friday as the storm bore down on the city's southern suburbs.

A girl who was also at the scene was taken to the Royal Adelaide Hospital with serious leg injuries, where she remains.

The Adelaide Hills and parts of the Fleurieu Peninsula took the brunt of Friday's wild weather, including strong winds and heavy rain, which passed after about an hour.


The Bureau of Meteorology said 35mm of rain fell in about 30 minutes, with flooding reported on a number of major roads.

At its peak the storm left more than 20,000 properties without power.

The State Emergency Service received more than 200 calls for assistance, with many calls about flooded roads that risked running into nearby homes.

It has advised residents assessing storm damage on Saturday to check the surrounds of their house for any leaves brought down by the winds, which could clog gutters and cause water to leak inside properties.