Outlook and outcome – May 2004 to July 2004

As expected rainfall was normal over much of New Zealand, except for above normal rainfall in Bay of Plenty and Gisborne. Higher than normal rainfall occurred in the west of the northern South Island with drier than normal conditions in the east.

Many districts recorded higher temperatures than forecast, due to a higher than normal frequency of northwesterlies, particularly in June. Temperatures were average as expected in some eastern regions.

River-flow conditions were forecast to be below normal in the east of the South Island, and near normal elsewhere. Flows were below normal in Northland and the South Island east coast, and normal to above normal elsewhere.


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 May to July 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.