Overview
April 2017 was characterised by higher than normal atmospheric pressure to the south and southeast of the South Island,
along with lower than normal atmospheric pressure over and to the north of the North Island. This pressure pattern
resulted in more northeasterly wind flow than normal, bringing with it moist tropical air masses and record-high
rainfall for parts of the North Island. These tropical air masses also delivered very warm temperatures to much of the
North Island. This pattern also led to a very wet month for the northern and eastern South Island, but at the same time
sheltering the West Coast and far south with drier conditions and warm temperatures for the time of year.