Police were called twice on Monday evening about the large gathering of cars viewing the bioluminescence along Westshore.
A police spokesperson said police received a report of about a dozen vehicles gathered at the foreshore on Ferguson Ave about 7.30pm.
The police received a second report about 8.30pm of "a large number" of vehicles doing loops up and down The Esplanade at Westshore.
The spokesperson said there were no recorded offences by people driving in the area.
The Hawke's Bay Regional Council marine and coast senior scientist, Becky Shanahan, said in a post for the council on Facebook that the bioluminescence was caused by plankton in the water that lit up when disturbed by movement like waves or rain.
"It's a naturally occurring algae, which can look like a red or orange paint in the water during the day, and is generally not harmful to humans."
She said some varieties could irritate the skin, so the council had taken a sample from Westshore beach to check its toxicity.
"If calm and warm nights continue, it may be possible to see it again, so go check it out if you get a chance."
Napier Port has been unaffected by the heavy fog, according to a spokesperson.
The spokesperson said fog horns heard from the ships are sounded to comply with maritime law.
"At times when visibility is restricted, Maritime NZ rules require vessels to use their fog horns (whistles) when manoeuvring in to or out of port."
Hawke's Bay Airport was forced to ground its planes in the morning due to the fog, according to a social media post, but flights had been rescheduled from 12.15pm onwards to fly again.
MetService spokesman Peter Little said the fog that has been seen in the mornings across Hawke's Bay will likely be gone by Wednesday as a northwesterly wind comes in.
"That's going to make the air on the east coast of the North Island much drier and warmer. With that sort of dry air and increased cloud cover as the front approaches, the likelihood of fog is significantly reduced."
He said light winds across the country and longer nights with more cooling at night had led to the foggy weather.
He said the thickest fog was detected south of Mohaka.
"Otherwise, it looks like more of the central parts, Napier, Hastings and further south, looks like they've been quite foggy too."
He said Tuesday morning was when the fog was heaviest.
He said it would get warmer for Wednesday, with 18C predicted overnight and 27C during the day for Napier and Hastings.
He said a front coming through later on Wednesday would make for a cooler Thursday.
"We'll see the forecast maximum for Napier drop to 20C on Thursday and 19C for Hastings."
Early Friday morning will be the coldest part of the week, with 6C for Napier and 4C for Hastings forecast.
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