NZ set to broil today as heatwave rolls on, with Auckland in for its hottest day of summer so far

The heatwave rolls on this week with temperatures increasing to as high as 38C in parts of the country.

Temperatures reached 35C yesterday, with similar weather continuing today.

"It is one of the warmest Januarys we've seen," NIWA's meteorologist Ben Noll told TVNZ1's Breakfast this morning.

Auckland has a predicted high of 30C today, which would make it the hottest day of summer for the region so far.

Hamilton, Wellington and the South Island will also feel the heatwave again today.

Taumarunui is the hottest in the North Island, reaching a high of 34C, and much of the South Island should expect highs of about 35C or 36C.

Thursday is expected to be the hottest day of the week, with temperatures in some places reaching between 36C and 38C in the afternoon.

The hot weather has left some areas very dry, including Nelson and the Tasman area.

"From about Westport on northward we are seeing extremely dry conditions for this time of year," Mr Noll said. "As we go into the next couple of weeks rainfall looks to be below normal, which is a continuing concern."