Most of Otago is drier than normal for this time of year, with the hardest-hit areas including North Otago, East Otago, Strath Taieri, Maniototo and Central Otago.
"It's certainly going to be a difficult winter for a lot of people," Hawea farmer Richard Burdon said.
North Otago Federated Farmers president Ross Ewing agreed, saying while farmers would welcome any rain, cool nights and wind meant it was getting late for vegetation growth to recover.
"It's getting serious. The trouble is, winter is coming and nothing is happening."
Oturehua farmer Ken Gillespie said just 190mm of rain had fallen on his farm since last May, making it one of the driest years he could remember.
The long-term annual average was 520mm.
Mr Gillespie said most farmers were down to basic breeding stock, and he had been feeding grain to his ewes for the last two weeks.
Most farmers had enough supplementary feed to get through winter, but it would be tight.
Mr Gillespie said 12mm to 15mm of rain in the next week or two would boost feed reserves, as long as there was no wind, which had negated any benefit from earlier falls.
Mr Ewing said most North Otago farmers would have adequate winter supplements, but the prolonged dry weather was starting to impact on next year's production.
The absence of the usual flush of autumn grass meant stock would not build up condition going in to winter, especially ewes, before rams going out in the next few weeks.
The middle of winter would be a testing time, he said, as winter crops were poor and stock would have to rely on a diet of silage, baleage and hay.
Most farmers had quit surplus stock at reasonable values, as store lamb prices remained high.
The Otago Regional Council said some Otago river flows in February were 20% of what was usual for the month
