WAIKATO and King Country temperatures for the next three months are most likely to be above average, with rainfall equally likely to be normal or above normal, according to NIWA’s climate projections.
NIWA correctly forecast a period of northerly winds in early May would deliver heavy rainfall and possible flooding to this region. Rainfall may then trend lower than normal from early winter as southerly winds become more common.
Soil moisture levels and river flows are equally likely to be near-normal or below normal. Weather patterns during May are expected to be variable with mixed air flows with a tendency toward more frequent southerly flows at the onset of winter, consistent with a developing El Niño.
A northerly-quarter airflow is expected to bring tropical moisture and very warm temperatures toward New Zealand via an atmospheric river from the beginning of the month, resulting in widespread, heavy rainfall and increased risk of flooding. More than a month’s worth of rain was expected for parts of the country.
For the coming three-month period, rainfall is about equally likely to be normal or above normal in the north and west of the North Island and the north and west of the South Island, while normal rainfall is the most likely in the east of the North Island, and below normal or near normal is about equally likely in the east of the South Island.
Seasonal temperatures are most likely to be above average for the north and west of the North Island and the north and west of the South Island, while above average or near average temperatures are about equally likely in the east of the North Island and the east of the South Island.
Coastal sea surface temperatures (SSTs) ranged from 0.20˚C to 1.08˚C above average during April. Coastal SSTs cooled during April, in some cases by as much as 0.95˚C when compared to March.
Soil moisture levels and river flows are most likely to be near normal in the east of the South Island and the east of the North Island, about equally likely to be near normal or below normal in the north and west of the North Island and west and north of the South Island.
ENSO-neutral conditions persisted in April, however, seas continued to warm across the equatorial Pacific consistent with a developing El Niño. El Niño conditions may arrive during winter.
