Outlook and outcome – July to September 2002

Rainfall was generally as expected over all the North Island as well as western, southern, and eastern South Island regions. In northern South Island regions rainfall was lower than predicted.

Air temperatures were much as predicted for all districts except the south of the South Island, which was warmer than predicted.

River flows were lower than predicted in northern and eastern South Island regions, and in northern North Island regions. Flows in East Cape and the central plateau were higher than predicted. Elsewhere, flows were as predicted.

The outcome maps shown here give the tercile rankings of the rainfall totals and mean temperatures that eventuated for these months. Terciles were obtained by dividing ranked July to September data from the past 30 years into three groups of equal frequency (lower, middle and upper one-third values) and assigning the data for the present year to the appropriate group. (Click to enlarge)

As an approximate guide, middle tercile rainfalls often range from 80 to 115% of the historical average. Middle tercile air temperatures typically occur in the range of the average plus or minus 0.5°C.