Severe thunderstorm warnings have been issued for parts of the South Australian coast, adding to the risk of bushfires from lightning strikes as the state endures a day of catastrophic conditions.
The warnings are in place for the lower Eyre Peninsula, the southeast and, most importantly, parts of the Adelaide Hills where authorities continue to patrol a large smouldering fire ground.
The storms could bring winds of up to 60 km/h, but there's not much chance of significant rain, the Bureau of Meteorology says.
Catastrophic bushfire conditions have been declared in three SA districts on Monday, the Adelaide Hills, the mid-north and Yorke Peninsula.
The temperature is forecast to reach 40C in Adelaide on Monday, with some regional centres to get even hotter.
But it's a cool change in the afternoon that is causing the most concern, with strong and shifting winds set to heighten the risk of bushfires spreading.
The Country Fire Service is particularly worried about the potential for breakouts from the Adelaide Hills fire, and from others burning on the Coorong, southeast of Adelaide, and on Kangaroo Island.
Another fire on the western end of the island was reported early on Monday but was not considered an immediate threat to lives and property.
The Adelaide Hills fire has already burnt through 25,000 hectares and destroyed more than 80 homes since it was sparked amid similar catastrophic conditions 10 days ago.
CFS chief officer Mark Jones said it was regrettable that the same conditions had returned so soon.
"The potential for hot-spot breakouts tomorrow is incredible across the whole fire zone," he said.