The heavens opened up on Sunday and Monday, with Myponga recording the State's top with 49 millimetres, while Robe enjoyed 45mm.

Widespread falls between 5mm and 20mm across most of the State's agricultural districts came just in time, with many farmers about to cut cropping programs because of poor rainfall since the Anzac Day weekend downpour.

Weatherzone meteorologist Matt Pearce said rainfall reached most of the State but failed to produce significant rainfall in the Murray-Mallee region with tops reaching 11mm at Peebinga.

"The bulk of rain has fallen from the north west corner of the State right down to the South East with most agricultural areas picking up at least 15mm," he said.

"But either side of that band in the far west, north and extreme coastal areas have not been able to pick up very much."

Mr Pearce said the rain was the result of a low pressure system and a cold front that tapped into a moisture plume coming down from the north west resulting in a large cloud band across the State.

Australian Crop Forecasters' managing director Ron Storey said farmers were "completely reliant" on these top-up rains to salvage the season.

"These rains were critical - SA had not received rain for a month and farmers were getting really concerned about earlier sown crops and crops they still had not planted," he said.

Although farmers were given a reasonable start, Mr Storey said they would be reliant on top-up rains throughout the season because of zero subsoil moisture levels after a dry summer and season last year.

"I think the rain has given them confidence, but farmers are still cautious - they need continuing rain for their crops to grow because there is such a lack subsoil moisture because of the last few dry years," he said.

"It has been a dry start but at least these rains have allowed farmers to get the crops planted."

* Extract from a full report in Stock Journal, May 28 issue.