Outlook and outcome – October to December 2002

Rainfall was as predicted for the South Island, apart from Nelson-Marlborough which was drier than expected. Northland and Bay of Plenty were also drier than expected, and Hawke’s Bay and East Cape received more rain than predicted.

Air temperatures were generally lower than expected, apart from Marlborough where they were near average, and western South Island regions where below average temperatures were as predicted.

River flows were much as expected over most of the country. They were lower than predicted in the west and south of the South Island.

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 October to December 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.