The Government is being urged to elevate veterinarians to critical worker status to help ease an acute shortage.
The NZ Veterinary Association (NZVA) says forecasters are predicting that the already strong El Nino conditions of spring 2015 will continue over summer and into autumn 2016 and it could rank amongst the four strongest El Nino events recorded along with 1972-73, 1982-83 and 1997-98.
"During El Nino NZ tends to experience stronger or more frequent winds from the west in summer, leading to drier conditions in the north and east, and more rain in the west," it warns.
"El Nino will increase the chances of more frequent and extreme weather events -- such as flooding and drought -- so you need to think about how you will manage your way through."
NZVA is advising farmers to "hope for the best, but plan for the worst".
"Look after your animals and regularly monitor their condition. The responsibility for ensuring the health and welfare of animals rests with the owner and person in charge. Animals need adequate feed and water and access to shade and shelter, important during adverse events."
The vets also urge farmers to check for seasonal problems such as facial eczema, footrot and flystrike and give thought to parasite control.
"Ask your vet if you're concerned about the health or welfare of your animals," it says. "If you are unsure where to go for advice or assistance visit the NZVA website or see your local vet.
"Feed is the key: know how much and what type of feed you will need. Organise the purchase and delivery of feed supplies before you absolutely need to."
Farmers are also advised to make decisions early and take action and to use water efficiently and plan for water restrictions.
"Monitor seasonal forecasts, extreme weather and fire warnings," NZVA concludes. "Ask for help if you need it."