New Zealand heatwave: Worst yet to come, expert warns

The heatwave isn't over yet. In fact, it's going to get worse, an expert says.

As the country rolls into Wednesday and Thursday, there's a chance we'll see the hottest temperatures of the heatwave, says NIWA meteorologist Ben Noll.

"Thursday is probably going to be the warmest day so that 36degC to 37degC range seems possible," he told Newshub.

"The hottest temperature we've seen so far during this heatwave is 35.3degC in Blenheim, so it is quite possible that we see temperatures exceeding that mark as we head into tomorrow."

A video posted to Twitter by NIWA shows how temperatures across New Zealand will be in the "above average" category.

Mr Noll said it's unlikely that even the hottest part of New Zealand could reach 40deg, the likes of which have been seen in Australia, which is grappling with its hottest January on record.

In New Zealand, the hottest areas on Wednesday and Thursday will be in north Canterbury and central Otago, according to Mr Noll.

"Areas north of Christchurch could be candidates for the warmest temperatures - places like Hamner Springs and then further south in interior parts of Otago like Cromwell or Alexandra," he said.

"These places could exceed 35degC in the coming days."

The heatwave will wrap up in the South Island by Friday night, he said, and those temperatures will then decline as we go into Saturday.