If you're battling to reach five plus a day in at the moment, this may be the reason.

Growers of green vegetables in the North Island have seen crops dying in the ground, as humid conditions make it easy for disease to spread.

A grower in Pukekohe, south of Auckland, Kiran Hari, says it's a 'sit and wait' situation until the weather improves for growers.

Hari says the issue has had the biggest impact of green leafy vegetables, which are particularly sensitive to high levels of moisture in the air.

Hari says the continued demand for high-quality product at a time when the supply is lower will "drive prices up".

Shoppers are already feeling the impact of this, with a retailer Kumeu Produce Market putting up a sign informing consumers that vegetable prices will be pushed up by the weather conditions.

Comparing the situation to a flood or drought, Hari says there isn't much growers can do when weather conditions aren't favourable to the crops being grown.

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He says the last couple of days the humidity has fallen, creating improved conditions for growing but it could be another couple of weeks before everything comes right.

Earlier this year, MetService meteorologist Brian Mercer attributed the high humidity to a strong northeasterly flow that is bringing warm air from the tropics.

"It is giving this relatively warm air, but it is also quite moist and what that means is even though the temperatures aren't super hot, because there's a lot of moisture in the air, the actual human body feels this high humidity feels much more uncomfortable."