The map below says it all, cold overnight temperatures can be expected for all regions in the North Island tonight as a ridge of high pressure settles in. Lows of -2 to -3 can be expected for inland sheltered spots south of the Waikato. Still quite cold towards some coastal spots but not as bad. Rural parts of southern Auckland may even get a light frost.
Frosty conditions can also be expected for the north and northeast of the South Island, lows dipping down to 0 or -1. A developing northwest airflow can be seen about the lower South Island due to the areas of red and orange showing up.
A northwest airflow brings warmer than average temperatures to many regions tomorrow, especially in the east and south of the South Island.
By Weather Analyst Aaron Wilkinson – WeatherWatch.co.nz