Locals on social media said the thick, black clouds from all around Auckland, including across the harbour in Pakuranga.
Four fire trucks were initially sent to the scene but as of 4.30pm only two remained.
Earlier, smoke was seen billowing from a metal processing plant in Papakura this afternoon after a piece of machinery caught fire.
A Fire and Emergency spokesperson said they were first alerted to the blaze on Hunua Rd about 2.30pm.
It was discovered when crews arrived that a metal shredding machine had caught fire, the spokesperson said.
The blaze was quickly controlled by firefighters and, as of 4pm, only two trucks remained on the scene dampening hotspots.