July was a month of two halves as New Zealand was first hit with cold and dry weather followed by wet and warm conditions.

In Niwa's national climate summary released today, it said anticyclones prevailing over the country during the first half of the month brought clear skies, light winds and frost.

But during the last two weeks of July, lows dominated and brought unusually mild conditions, northeast winds and high rainfall to northern and eastern regions of the North Island, as well as Nelson and Marlborough.

For the whole of the month, higher than normal pressures produced more northeast winds than usual over the North Island.

Of the six main centres in July, Tauranga was the warmest, wettest, and sunniest, Christchurch the coolest, Dunedin the driest, and Wellington the cloudiest.

According to Niwa, temperatures for the month as a whole were near average for many regions, except for the south and west of the South Island and along the northeast coast.

The nationwide average temperature for July was 8.4 degrees Celsius.

The highest temperature was 22.6C in Rangiora on July 15, while the lowest temperature was -11.3C at Ranfurly on July 2.

It was "extremely sunny" for the western South Island and central-west North Island with sunshine totals exceeding 125 per cent of normal, though it was "very cloudy" in Gisborne, Wellington and Nelson with between 75 and 90 per cent of normal sunshine totals.

There was more than 150 per cent of July normal rainfall recorded in parts of Northland, Western Bay of Plenty, Waikato, Gisborne, southern Hawke's Bay, Wairarapa, Tasman, south Canterbury, and parts of Otago.

Other regions with above normal rainfall, between 120 and 149 per cent, were Taranaki and Westland.

On the other hand, it was unusually dry for Southland, with rainfall totals less than 50 per cent of normal, and it was the driest July on record for Invercargill and Tiwai Point.

It was also dry in north Canterbury, Fiordland and between Wanganui and Waiouru.

- © Fairfax NZ News