Pastures are underwater, crops have been destroyed and culverts and valuable feed have been washed away due to heavy rainfall since Friday.
Auckland Federated Farmers president Alan Cole said farms were completely smashed because of the sheer volume of water.
30 January - Red level weather warnings (the most severe warnings) are currently in place for Auckland and the Coromandel Peninsula. Because of this the National Emergency Management Agency has issued a safety warning that the forecast heavy rain could cause flooding, slips and damage. Scroll down to find the full list of their advice for keeping safe.
"Some farms have lost all of their culverts, there's a lot of fencing down and one dairy farm is under water so those cows had to be moved pretty quickly, Cole said.
"It doesn't matter how big your infrastructure is; nothing was prepared for that amount of water."
Cole who farms beef near Clarks Beach, south west of the city, said he had over 300mm of rain during Friday and Saturday.
"The damage is widespread across the south here in Franklin, right through parts of Karaka, Patumāhoe and Pukekohe.
"Farmers are facing a huge cleanup job but many are just cautiously watching the weather forecast - as a lot more rain is expected to fall this week.
"The main thing is that everyone is okay and there have been no reports of stock loss."
- Are you an affected grower? If you'd like to talk to RNZ about what's happening on your field, you can contact the rural news team at email@example.com.
North west of Auckland city Helensville dairy farmer Scott Narbey said one third of his farm was underwater.
Narbey said the floodwater was a metre and a half deep in some places, the worst he had ever seen.
"The water from the Waitākere [Ranges] and Kumeu all came down past us and has gone over the top of our stopbanks."
With more rain forecast, Narbey said there was not much they could do until the water started to recede, but he was anticipating a fair amount of pasture damage.
Nearby, sheep and beef farmer Richard Kidd said his farm seemed to have missed the worst of the heavy rain, but the damage in the surrounding area was very evident.
"We've farmed up here for 45 years and I've never seen the water so high... the highway has been shut, there's rubbish on fences right to the top wire."
Out the back for a decent look today. No quad access for the foreseeable future. Electrics and boundary fences smashed, so lacking any secure paddocks on this block. Hope everyone else doing ok @MorrisonFarming @farmingwomennz @Infideliter2022 pic.twitter.com/Jmbzcj1rEQ— Nicky Berger GrassFedInTheCity (@berger_nicky) January 28, 2023
Further south in the Coromandel, the region's Federated Farmers president, Robert Craw, said there was surface flooding and slips but farmers were holding up.
"It looks like we've come out okay compared to other areas, there's a bit to clean up but we've had worse."
Fonterra said there was some disruption to milk collection, mainly in the Coromandel, where flooding and road slips have made getting tankers onto farms more difficult.
Growers face 'one hell of a mess'
Fruit growers in the Bay of Plenty say orchards have also been left under water.
Te Puke is a key kiwifruit growing region - growers there were busy assessing damage when RNZ contacted them.
Many were concerned about the Number 4 bridge being washed out as it was a vital access route for many orchards and the harvest is set to start in March.
The region's Federated Farmers president Brent Mountfort said the heavy rain had come on top of consistent rain over the past two months.
"There's a lot of accumulative issues, for example, around the maize crops. A lot had already failed due to wet weather and now some are fully underwater so moving forward there's going to be a winter feed issue for some of our dairy farmers, so that's a real concern.
"I've heard of a few farmers who have put their maize in twice and it's just not growing. When you drive around the region you can get a good look at the crops and yeah, they're not looking too flash."
Mountfort said farmers were keeping in touch with each other so those who were hardest hit have been getting a hand to clean things up.
Farmers needed to remember if they wanted a hand with anything they should contact Federated Farmers or the Rural Support Trust, he said.
Onions have been washed off paddocks and onto roads and potato paddocks have been left underwater following Auckland's downpour.
Growers in the key growing region of Pukekohe were today pumping water off their farms and unblocking drains in preparation for more rain this afternoon.
Pukekohe Vegetable Growers Association head Kirit Makan said the heavy rain had left "one hell of a mess".
"There's water and soil everywhere it shouldn't be and yeah some crops have moved down the road.
"The impact on crops is variable depending on the land; in the flatter areas crops will drown in water but if the land is more free draining the crops should be okay."
Makan said onions had been particularly hard hit as it was the time of the season where they were lifted out of the ground and left sitting on the soil to dry out.
"So they've simply washed away, if the public finds vegetables on the roads they shouldn't eat them because they could be contaminated.
"It's too early to tell what the overall impact to supply will be at the moment, but this will hit some growers' businesses hard."
Another Pukekohe vegetable grower, Bharat Bhana, said he was too nervous to go out and survey the damage to his crops.
"I'm waiting for a break in the weather to head out but at the same time I don't really want to. I know some of our potatoes are underwater, they only need to be like that for a couple hours and they will rot."
Industry group Vegetables New Zealand said it had done initial welfare calls to growers across affected regions to check on the welfare of growers and their families.
Chairman John Murphy said they would conduct more detailed assessments of the damage to crops in the coming days.
Because of the red level weather warnings issued for Auckland and the Coromandel Peninsula, the National Emergency Management Agency has posted advice on how to keep safe:
- Red weather warnings are the most severe warnings. The forecast weather could cause further flooding, slips and damage
- People should stay up to date with the forecasts from MetService and continue to follow the advice of civil defence and emergency services
- If you have evacuated, please stay where you are until you are given the all-clear to go home.
- Stay away from floodwater. Always assume that all flood water is potentially contaminated and ensure hands, clothes and property are thoroughly cleaned after contact with flood waters
- It is important to clean and dry your house and everything in it. Do not eat garden produce if the soil has been flooded
- Throw away all food and drinking water that has come in contact with floodwater, including things stored in containers
- Information about where to get help can be found on the Civil Defence website and from Auckland Emergency Management