Coolest May since 1992

New Zealand moved from summer to winter abruptly in May, according to the National Institute of Water and Atmospheric Research's latest climate statistics.

The national average temperature for the month was 9.6C - 1.1C below average and almost 4C cooler than the balmy month of April. It was the coolest May since 1992.

Of the five main centres, Auckland was the warmest and wettest. Hamilton was by far the sunniest, and Christchurch the driest and coldest.