It is still possible that a developing El Niño event may influence New Zealand climate by spring 2002, but it is not expected to affect New Zealand climate over the coming winter. Conditions in the tropical Pacific that indicate how El Niño is developing have changed little between March and April. Present indications are that this El Niño is likely to be a weak to moderate event.
Sea-surface temperatures around New Zealand are expected to be near normal for the May-July period.
New Zealand temperatures are expected to be above normal in the north and west of the North Island, normal in the west of the South Island, and normal or above elsewhere.
Rainfall is expected to be normal or above normal in the north and west of the North Island, normal or below normal in the east of the South Island, and near normal elsewhere.
Normal soil moisture levels and river flows are predicted for all regions of the country, except for normal or below normal river flows in the east of the South Island.
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).