Thirty degrees of hot in Hawke's Bay - night-time swelter set to continue

Hastings had reached 28C and Napier 29.1C by lunchtime on Tuesday. Photo / Warren Buckland

The heatwave has hit Hawke's Bay.

The official thermometer for Napier was already at 29C by 11am on Tuesday, and between 1 and 2pm, it had hit 30.3C.

The region is one of many parts of the country experiencing hot temperatures in what is the second week of summer, with temperatures reaching 25.5C in Hastings by 9am then 30.5C at 1pm.

"The temperatures above 30 degrees are getting into that seven-degree range above what is average for December," MetService meteorologist Lewis Ferris said.

Wairoa was also hot at 27.5C and the MetService station at the Takapau plains had its hottest temperature between 8 and 9am at 23.5C.

And while the daytime temperatures are hot for this time of year, it's the warm overnight temperatures that are particularly unusual.

MetService meteorologist Stephen Glassey said Napier's minimum overnight temperature on Monday was 22.4C.

"That's quite a decent temperature for a maximum, but that was the minimum last night."

Ferris said these overnight temperatures "are definitely on the rarer end of the spectrum".

"Almost every December Napier would see a 30-degree day but not every year would you have a temperature stay up over 20 degrees overnight."

And this is expected to last the next couple of days, with overnight temperatures forecast at 21C in Napier tonight and similar on Wednesday night.

That's eight degrees above what is normal for this time of year, Ferris said.