Earlier this week, we told you about a river in outback South Australia that was running for the first time in 18 months, and finally, a large chunk of the southern half of SA has cashed in on Australia's big wet.

Many South Australian towns recorded their best 24-hour rainfall in months or even several years up to 9 am on Friday morning.

Forecast districts that were the recipients of the heaviest falls overnight included:

• Yorke Peninsula and Kangaroo Island
• Adelaide and Mount Lofty Ranges
• The Flinders and Mid North
• West Coast, Lower Eyre Peninsula and Eastern Eyre Peninsula

And some of the 24-hour rainfall readings of note included:

• Kadina 31.8 mm (heaviest in almost five years)
• Nuriootpa 27 mm (heaviest in just over four years)
• Whyalla 46.4 mm (heaviest in almost two years)
• Mt Crawford 35.6 mm (wettest November day on record in 25 years of records)
• Adelaide 13 mm (not a huge amount but still the second-wettest day in almost four months which have seen relatively meagre rainfall)

This was actually quite an unusual rain system

Typically, rain moves fairly briskly across southern half of South Australia, usually from west to east.

What made this rain so persistent in many areas (and also meteorologically interesting) was that it was associated with a low pressure system which was sitting just to the north of Adelaide over the northern Flinders region.

This low (with associated front and trough) meant that a large blob of rain-bearing cloud parked itself over parts of SA for a longer duration than most systems tend to do in this part of the world.

Hence we saw continuous steady rain for around 24 hours at many locations.

Image: The synoptic chart at 7 pm Thursday night (AEDT) showing the low funnelling persistent rain into southern SA.

As for the rest of the week in SA, the low has now pushed its way eastwards, but showers and brisk winds will generally continue over Adelaide as a high pressure ridge builds from the west, and a new front pushes in from the south on Sunday.

Showers will be intermittent in southern SA, which is more typical of the region, with northern parts of the state returning to their usually dry self.