Upper Clutha sheep farmers are weaning lambs two to three weeks earlier than normal to take advantage of high store lamb prices, but also in response to an exceptionally dry spring and early summer.
Hawea farmer Richard Burdon said he emptied just 5mm of rain out of his gauge in November and 3mm so far for December, months he usually records 50mm for both.
The National Institute of Water and Atmospheric Research (Niwa) warned the South to expect a drier than normal summer, as a moderate to strong La Nina weather pattern took hold.
A Niwa senior climate scientist, Georgina Griffiths, said the La Nina weather pattern was already being felt in the South with a hot and dry November and December.
Waikato, Bay of Plenty, Auckland and Northland are bracing for a summer drought, but the South may not escape unscathed, with many areas likely to experience drier, warmer summer conditions than usual.
"Typical La Nina weather tends to be warmer and drier in southern parts," Ms Griffiths said.
Mr Burdon agreed, saying the real effects would be felt in autumn and winter when pasture cover and winter feed crops could be lower than normal because of a lack of rain.
But in the meantime, farmers were selling store lambs for $2.60 a kg net and taking advantage of strong early season demand, Mr Burdon said.
The Upper Clutha region appeared to be hit harder than other parts of Central Otago.
Normally, lifestyle blocks are a source of hay and silage for Upper Clutha farmers, but the dry weather has decimated yields.
Mr Burdon said he normally made 180 bales from one dryland block he has access to, but this year made just 51.
His silage crops were yielding less than 40% of normal.
Niwa warns that from December to February, the West Coast, inland Otago, Central Otago and Southland are expected to have below average summer rainfall and above average temperatures but, importantly for farmers, below normal soil moisture and river flows.
Eastern parts of Otago and coastal Canterbury are expected to have above average temperatures and near normal seasonal rainfall, with soil moisture levels and river flows expected to be normal to below normal.
The Otago climate and pasture update, published by the Otago Regional Council and Niwa, said looking ahead from November to January, it expected above normal air temperatures across the province and normal or below normal rainfall, soil moisture levels and river flows.
In what has become a year to forget, the BNZ weather wrap publication estimates the spring storms and now dry weather particularly in the north of the North Island could cost the economy $1 billion.