A repeat of the mass deaths caused by a heatwave in 1973 is unlikely to happen again, poultry farmers say.
Nearly 30,000 chooks died across Canterbury and Marlborough, as the mercury hit a record high of 42.4degC.
Poultry Industry Association executive director Michael Brooks says thankfully, technology's come a long way since then.
Every farm today is required to have ventilation, fans and computer generated cooling systems as well as back-up generators.
"It's a whole new system," Mr Brooks told Newshub.
"It does give that advantage that previously wasn't there, and enables that adaption against the influences of this extreme weather we're experiencing at the moment."
- How to get to sleep during sweltering summer temperatures
- Record-breaking weather: Why is it so hot?
- How to care for your pets in near 40degC heat
Mr Brooks says chickens struggle to regulate body temperatures in extreme temperatures.
"They'll be spreading out their wings, trying to cool down, and trying to release heat from their throats - that'll be through movement just behind the wattle."
He says owners should put ice in the water, and need to make sure the chickens have plenty of shelter from the sun and heat.
So far this year, the death of one person has been directly attributed to the scorching heat - a Christchurch woman in her early 60s .
NIWA is predicting temperatures could reach the low-40s by Tuesday.
"I'm not going to promise [40degC], but it's certainly a distinct possibility. I wouldn't say it's a likelihood, but it's in the conversation," meteorologist Chris Brandolino told The AM Show last week.