Three-month outlook

The outlook for March to May 2003

The El Niño event in the tropical Pacific is nearing its end, but its influence should be felt on New Zealand into April. Autumn 2003 is expected to be influenced by higher than normal pressures over the Tasman Sea with stronger than normal southwesterly winds across New Zealand in March and April.

Temperatures are expected to be near average over the north and east of the North Island and northern South Island, and average or below average elsewhere.

Below normal rainfall is expected in the east of the South Island with normal or below normal rainfall in the eastern North Island. Near normal rainfall is expected elsewhere in New Zealand.

Normal or below normal soil moisture levels and river flows are expected in most regions.

There is a near-average risk of a tropical cyclone affecting New Zealand during the remainder of the cyclone season. On average, one ex-tropical cyclone affects the country during the cyclone season.

A. Climate models give no strong signals about how the climate will evolve, so we assume that there is an equal chance (33%) of the climate occurring in the range of the upper, middle or lower third (tercile) of all previously observed conditions.

B. There is a relatively strong indication by the models (60% chance of occurrence) that conditions will be below average, but, given the variable nature of climate, the chance of average or above-average conditions is also shown (30% and 10% respectively).