A flood watch has been issued for the Mount Lofty Ranges as the weather continues to deteriorate and winds strengthen.

A wind gust of 109km/h was recorded at Strathalbyn at 12.29pm. Hindmarsh Island recorded 93 km/h just after 1.30pm.

Emergency services are being kept busy, with reports a motorhome has been blown over at Woodchester.

There have been multiple calls for help to assist residents with fallen trees in Strathalbyn and at Hindmarsh Valley, Port Elliot, Milang, Belvidere and Goolwa.

There have also been calls from residents around Strathalbyn who have had water tanks blown away.

The Bureau of Meteorology says significant rainfall is expected from Thursday afternoon into Friday with flooding possible from late Thursday evening.

Widespread rainfall totals of 50-80 mm are likely with local heavier falls up to 100 mm possible.

Main areas of the rainfall are expected be the Fleurieu Peninsula, Onkaparinga Catchment, Torrens Catchment and Adelaide metropolitan rivers and creeks.

The most intense rainfall is expected during Thursday evening into Friday morning.

The forecast rainfall is expected to cause rises in water levels in rivers and creeks across the Flood Watch area.

Riverine flooding is possible from Thursday late evening, particularly in upper Onkaparinga and Upper Torrens river catchments which may lead to some road closures and disruption to travel and transport.

Catchments likely to be affected include the Fleurieu Peninsula, Onkaparinga River and Torrens and metropolitan rivers and creeks.

Sandbags are available from the SES at these locations.

The latest severe weather warning issued by the Bureau says the most recent front associated with a deep and complex low pressure system will result in a broadly strong to damaging northwesterly airstream with squally showers and thunderstorms, extending east.

Northwesterly winds will continue to strengthen on Thursday with southern and central parts of the state forecast to be impacted by potentially damaging winds.

DAMAGING WINDS will average 50-70 km/h at times with gusts in excess 90 km/h.

Winds will peak Thursday afternoon and evening.

Conditions are easing over western districts before contracting to elevated terrain Thursday evening and early Friday.

Squally showers and thunderstorms are forecast to extend across much of the agricultural area during Thursday.

Locations which may be affected include Adelaide, Victor Harbor, Port Lincoln, Whyalla, Mount Gambier, Port Pirie, Maitland, Murray Bridge, and Kingscote.

The State Emergency Service advises that people should:

* Move vehicles under cover or away from trees;

* Secure or put away loose items around your property.

* Don't drive, ride or walk through flood water;

* Keep clear of creeks and storm drains;

* Stay indoors, away from windows, while conditions are severe.

The next Severe Weather Warning will be issued by 5:00 pm ACST Thursday.

For flood emergency assistance contact the State Emergency Service on 132 500.

For life threatening emergencies call Triple Zero (000) immediately.

Check road conditions before travelling.

Sealink Ferry operations have been suspended.