Severe thunderstorms are expected to approach the Bay Thursday and Friday as well as high humidity.
A deep low that can generate flooding rains, strong winds and dangerous beach conditions is in the forecast for the end of the week.
The next three days will be dominated by strengthening northerly wind, which will supply heat and moisture (humidity) supporting the unstable current of air.
Afternoon thunderstorms are likely in interior regions in southern part of North Island today and tomorrow.
They will also spread in the South Island tomorrow and Thursday as a low-level northerly wind strengthens.
Some storms may be severe, producing locally heavy rainfall exceeding 30mm/h, gusty winds, and possibly hail.
Following the northerly wind, a rapidly developing low pressure will approach the North Island south-eastward from the northern Tasman Sea.
Northland and Auckland will be exposed by strong winds over gale force at times with wind gusts on Thursday and Friday.
Heavy rain is expected in those areas in Thursday daytime, and Bay of Plenty and Waikato in Thursday night, spilling over into Friday. Over the few days some areas may get over 100mm of rain.