Export lamb production in 2010-11 was expected to finish at about 19 million head, down 11% on the previous season, according to the ANZ Agri-Focus report for July.
Snow, rain and wind hit the South last September, claiming the lives of a million lambs, while the North Island was also affected by wet, cold weather during lambing.
Lamb weights were hitting record levels, which was providing an offset to the lower number of lambs, the report said.
Higher store prices for lambs and ewes and wet weather had seen a drop-off in the kill figures over the last month.
Mutton production was down 5% in June and had dropped off even more this month. Overall mutton production was still likely to finish about 20% up on last season, meaning opening ewe numbers were likely to be back 1%-2% at June 30.
North Island scanning results have been reported to be poor. Conception rates were affected in February when feed was only just starting to come away and ewe condition was only just starting to lift.
Sub-clinical facial eczema and worm burdens might have also had a bigger influence than first expected. Recent South Island scanning results have been better, providing an offset.
The good autumn and low lamb production was creating an unusual season kill pattern for prime lambs.
The national average lamb weight was likely to be finished about 18.2kg this season - above 18kg for the first time and 3% up on last year.
Weights were running 2.2% ahead for the year-to-date but nearly 10% ahead for this time of the season.
Year-to-date wool exports for 2010-11 were down about 7.5% on last year to 114,000 tonnes. As farmers "took the money and ran earlier" in the season, export volumes had dropped off 25% to 30% in recent months as lower sheep numbers "come home to roost", the report said.
A Silver Fern Farms market update reported yesterday that European lamb markets remained under price pressure as the UK domestic season reached its peak production period. UK lamb sales were down 13% in June, compared with last year.
"With this reduction in sales activity coming during the height of their lamb production, it creates the need for the UK to export greater volumes in the EU continental trade, which is impacting upon general lamb prices in these markets," the update said.
While New Zealand was exporting very low volumes to the area at this time of year, it did affect future lamb prices.