Adelaide has gone from setting summer heat records to having its wettest day for February in four decades and the rain is still falling.

The latest wave of extreme heat ended in the past day when rain swept in.

Flooding was reported across the city and many roads became chaotic as they turned into deep streams and became gridlocked with traffic.

Rail boom gates were stuck in several locations, including on busy South Road, leading to enormous traffic jams.

At Woodville in the north-west suburbs, the deep waters on Port Road caused major problems.

Emergency services have dealt with hundreds of calls about flooding, including at Findon and Hindmarsh.

Adelaide has had more than 70 millimetres of rain since the deluge began and plenty more is expected before it eases later on Friday.

Senior weather forecaster Mark Anolak says a big part of South Australia is getting the heavy rain.

“Northern Eyre Peninsula, the mid-north, northern parts of the Mount Lofty Ranges and the Adelaide area itself. Also into the Murraylands and Riverland districts,” he said.

“We’re expecting a band of very heavy rainfall through there and yeah wouldn’t be surprised to see 50 to 100 millimetres through that band.”