Residents have been warned to brace themselves for severe weather on Thursday, particularly on the West Coast.
The State Emergency Service issued the alert on Wednesday afternoon.
The Bureau of Meteorology predicts damaging winds and gusty showers on Thursday over the West Coast, Flinders and south of the Pastoral districts associated with a deep low-pressure system.
Broadly across the south of the state, including Adelaide and the Mount Lofty Ranges, showers and thunderstorms may produce heavy bursts of rain and small hail.
The emergency service's chief of staff, Darryl Wright, reminded people to prepare for the conditions to keep themselves and their properties safe.
"Securing loose items and keeping your gutters and downpipes free of leaves and other rubbish will reduce the risk of damage to your home and business," he said.
"If roads become flooded, don't risk it. Never drive through floodwaters and make sure children don't play in or near fast-flowing water."
He reminded people, particularly those in the western and northern parts of the state, to be prepared for wet and windy conditions on Thursday.
"We ask people to be mindful about where they park vehicles or set up camps. It is never a good idea to park or camp under big trees as they can become unstable and fall during strong wind events," he said.
"This also includes not parking vehicles and setting up camps in or around creek beds."
The service encourages people to listen to local radio stations and monitor the SES website and social-media channels for information, updates and advice.
Information and steps on how home and business owners can prepare for the conditions can be found on the website at www.ses.sa.gov.au
For emergency help in storms and floods, call the SES on 132 500. If the matter is life-threatening, call Triple Zero (000).
More South Australian weather information can be found at www.bom.gov.au