"We're looking at a season tonnage of around 20,000 tonnes and we should be finished harvest by about mid-June.
"Currently, weather conditions are ideal for both grain dry-down and harvest."
Glencore Grain regional manager Dave Corrin said they were about 40 per cent of the way through their pick.
"Our yields are above average and the quality is very good.
"So far it has been a perfect season harvest-wise with the good weather conditions, and that's also allowed croppers to do spring ground work now, discing and harrowing harvested paddocks.
"It brings the whole season forward for spring, which is really good."
Glencore Grain will harvest 8000 to 9000 tonnes of maize this season.
The company has been harvesting around Gisborne and Wairoa.