Waves of smoke are pouring across the Tasman from the Australia bushfires, causing "unusually dark and foreboding" skies in the South Island.
MetService says smoke particles have been pushed over by an unbroken northwesterly that's flowing over the country like a river.
"A SnapitHD webcam captured the hazy sunrise over Wanaka this morning which many others across the country also experienced," MetService said on Twitter.
"This is due to smoke from the Australian bush fires being carried across the Tasman by an unbroken northwest flow."
In Christchurch, there has been a reddish blanket across the city for the entire day.
The haze was so thick in some areas people were driving with their headlights on. The fire service has fielded calls from across the lower South Island from people worried there were blazes nearby.
The ominous burnt orange skies have been captured in some stunning images posted to social media.
"The sky is unusually dark and foreboding over Dunedin, NZ, this morning," one person tweeted.
"Holding Australia in our thoughts. Wish we could send you some South Island rain."
But the smoky skies won't last for long. Wednesday will be the worst of it because a southwest change tomorrow will push it away.
What are the dangers?
Most of the smoke to reach to New Zealand will be very high and diluted, however people should still be cautious about their exposure.
"Particulate matter smaller than 2.5 micrometres can make it past our body's natural defences that filter out particles (ie the hairs in our nose) and go deep into our lung tissue and potentially into our bloodstream," said Tara Strand, rural fire research leader at Scion Rural Fire Research Group.
"Long exposure to smoke is not recommended for healthy individuals and sensitive individuals (ie asthmatics) need to monitor their exposure closely even in light smoke."
NIWA meteorologist Ben Noll said people sensitive to fine particulates will want to take extra care by closing windows and not running their air conditioner.