MetService says winter rainfall to date has been around 70% higher than usual in the upper North Island.
Auckland usually gets around 130mm of rain in July, but saw 215mm this time.
NIWA says Auckland's July rainfall was the second-highest on record.
Parts of the North Island received about 50% of their normal rain earlier in the year - now they have received around 170%.
Horticulture New Zealand says the weather is having a big impact on vegetable growers, cutting production for some by about 35%.
The chief executive, Peter Silcock, says cloud cover has also hampered growers and a reduction in supply is driving up prices.
Mr Silcock says the weather has had a particularly big impact on vegetable growers, with plants dying from hail damage or because the soil is water logged.
He says it could take up to four months before growers can return production levels to normal.
Meanwhile, New Zealand's largest mall operator, Westfield, say it has noticed an increase in foot traffic during the wetter periods.
The House of Travel says it has experienced a big increase in people booking holidays to warmer places like the Pacific islands and Australia.