Tighter bunches can mean the grapes are more prone to fungal infections.
"This stinking hot weather has been very positive," he said, before comparing the season with 2013 which was dry but not as hot, and was also recorded as the driest season in 70 years.
A specific measurement called "growing degree days" is used to assess the season, both throughout and afterwards.
When the season began temperatures were on the cooler side, he said, but they were now "sky-rocketing".
The warm, dry conditions were expected to continue for a while longer, boosting hopes that the season would be sealed without any hiccups before harvest.
Mr Henley said it was difficult to assess the season for sauvignon blanc because it was grown throughout Hawke's Bay, stretching from Porangahau to areas further north.
He said chardonnay was still very popular and was having a good season.
The "flagship" white wine was a full-bodied variety with balanced acidity and richness.
There was also a strong focus on the full-bodied red varieties like syrah - which is usually an elegant and lightly-perfumed drop - and merlot.
Mr Henley said the grape-growing characteristics of Hawke's Bay could not be compared with anywhere else in the world because the climate was unique.