Farm sales for the three months to August are down 20 percent compared to the same period last year, with 311 properties sold - 82 fewer than last year.
The Real Estate Institute's All Farm Price Index fell 1.9 percent in the three months to August compared to the three months to July.
Rural spokesperson Brian Peacocke said the wet weather had been extremely frustrating.
"It's been so wet it's causing huge management difficulties and with that scenario, up until now, people haven't wanted to see anybody on the properties ...
"It's so muddy and there's been a lot of pasture damage done. Feed supplies are quite tight so with that mix people are waiting until things are looking a bit better."
He said the same period last year was also wet, but this time around it's worse.
"Unprecedented rainfall for some months on end, it just hasn't given up.
"The added frustration is for those looking to get ground prepared for sowing crops, in some cases that involves spraying the annual or short term pasture ...
"The machinery just can't get on the ground, it's too wet."
Mr Peacocke said the market should start to pick up in the next month and and overall the rural sector is in good shape, particularly with horticultural properties in hot demand.