As large parts of South Australia swelter through yet another day of above 30-degree heat, it is hard to believe that temperatures are expected to plummet into Easter Sunday by as much as 15 degrees.

On Good Friday, hot air from the interior ahead of a slow moving cold front brought the hottest day this late in the season to Adelaide in 133 years of records.

Although cloud cover ahead of the approaching cold front is inhibiting heating somewhat, Saturday's 32.2 degree temperature measured at 12:45pm in Adelaide has already exceeded the previous 98-year record for late-season heat, and could still be as warm as Good Friday.

Apart from forcing hot air from the interior further south to bring unseasonable heat, fire danger is also being elevated ahead of the system by strong and dry northwesterly winds. A Fire Weather Warning is currently in place for the West Coast, Eastern Eyre Peninsula, Lower Eyre Peninsula, Mid North, Mount Lofty Ranges and Yorke Peninsula forecast districts, where total fire bans are also in place.

The cold front is expected to arrive over Greater Adelaide during the late evening or overnight into early Sunday, likely translating to temperatures still exceeding 25 degrees well into the evening.

Daytime maximum temperatures are expected to be significantly lower in the wake of the front, reaching only about 20-22 degrees across southern parts of the state on Sunday. To give a sense of how strong this system actually is, Nullarbor was about 20 degrees cooler at 2:30pm on Saturday than for the same time yesterday, after the front had crossed.

Apart from bringing significant cooling in its wake, the system should also bring widespread falls of 5-10mm across the southern parts of the state into midday on Sunday.

Given the high fire danger across the state at the moment, any thunderstorms and associated lightning could only enhance fire ignition potential. Visit http://www.weatherzone.com.au/warnings.jsp for the latest severe weather warnings associated with this event.