Prices for trade lambs in major selling centres in NSW and Victoria consistently made $100-$130 last week on the back of widespread rain.
Trade and heavy mutton was also a big mover selling from $52-$78 in Victoria, while heavy cross bred wethers sold to a top of $86.60.
According to Meat and Livestock Australia's National Livestock Reporting Service, rain across the eastern states is also expected to further tighten supply in the coming week.
Competition for lambs has steadily crept upwards, as the season starts showing signs of winding down.
Processors have been cautious, and in many cases have taken a wait and see approach with regards to supply in the physical markets before adjusting their rates.
The greatest gains received this week were for the slaughter grades, with processor demand being very solid for these categories due to their limited availability.
The central west of NSW reported the trade lamb indicator between 380¢/kg and 393¢/kg with the northern NSW trade lamb indicator ranging between 343¢/kg and 364¢/kg.
Trade lambs in Victoria mostly sold just below the 400¢/kg mark, with the indicator ranging from 386¢ and 397¢/kg cwt.
Very few lambs were offered in the south east of SA, while supplies still remain steady at the SA Livestock Exchange, where trade weights averaged 349¢/kg cwt.
In WA there is a very different scenario.
Heavyweight lambs sold to a top of $88 at Katanning last week, while in Midland they hit $84. Trade and heavy mutton is averaging $46.
Quality, heavy weight lambs are in very short supply though with higher numbers of store sheep on offer as producers are forced to destock because of seasonal conditions.
Landmark Katanning agent Mark Warren said there were 20,000 sheep yarded at Katanning last week.
"That will increase further if we don't get rain in the next couple of weeks," he said.
"Farmers are now considering weaning lambs early and selling off ewes if the rain doesn't come.
"Prices are really reflecting the quality of the sheep coming in.
"Mutton firmed but the grazier type sheep are struggling simply due to their condition."
Mr Warren said there had been some interest from eastern states processors but no grazier enquiry as yet.
"There has been enquiry from the east regarding the coming June special sheep sale and we expect them to be operating in that market," he said.
Tony Douglass, Elders Katanning, said farmers in his area were becoming increasingly concerned with the lack of rain.
"They are trying to hold onto sheep as long as possible, but if there isn't any rain in the next week then many will be forced to off load," he said.
"We would expect to have another big yarding at Katanning this week with predictions of 30,000 to be on offer."
Mr Douglass said there had been some enquiry from the east mostly in regard to next week's June special sheep sale.
"We are getting a couple of calls a day from the east, but they are very price conscious due to freight costs and so forth," he said.
Landmark commercial livestock manager Damian Halls said farmers in the north of the state are busy offloading sheep.
"They have been trying to hang on for as long as possible, but just haven't got the feed," he said.
"Many are now in the position where they have ewes in lamb and they are too far advanced to truck.
"Anything that is within a month of lambing can not go on trucks and so many of them are holding on until the ewes have lambed and will try to sell them with lambs at foot."
Mr Halls said prices were holding up reasonably well despite an oversupply of older ewes.
"The mutton market is still firm and demand for finished crossbred lamb is keeping the price up," he said.
"The shipping market is also very strong, but they are having difficulty finding sheep in the right weight range."
Mr Halls said rising sheep prices in the east had driven enquiry from across the border.
"They are buying to a price as they have to take freight into account," he said.
"Most of the activity is from restockers who are opportunity buying and I would expect to see more eastern states activity at next week's June special sale."
Phil Barber, Elders Corrigin, said it was the first time since 1976 that he had seen prices for sheep not paying the freight bill.
"Prices for poorer quality old ewes have dropped significantly because the market is currently saturated," he said.
"Some I sent away recently only made between $2 and $5.
"It is lucky the trade lamb and shipping markets are pretty buoyant at the moment.
"Anything that is in shipping condition is making good money and prices for lambs in good trade condition are also strong."