Almost 20,000 South Australian homes without power

Thousands of people are without power in South Australia due to a massive blackout across the state.

Almost 20,000 properties including homes and schools are being affected by 75 power outages in the state's south.

Extreme weather conditions are being blamed for the blackouts, and earlier today the Bureau of Meteorology issued a severe thunderstorm warning for Adelaide.

Damagings winds are expected through Adelaide, Port Lincoln, Whyalla, Maitland, Renmark and Murray Bridge.

More to come.