New Zealand climate in May 2005

Record rains lashed Bay of Plenty, with severe flooding. Tauranga recorded 634 mm (695 percent of normal), its wettest calendar month for any time of the year in more than a century, including its heaviest 1-day rainfall on record (347 mm on 18 May).

May was very much warmer than usual in the North Island, but temperatures were below average along the South Canterbury and Otago coasts. The national average temperature for May was 11.4 °C, which was 0.7 °C above the historical average.

For more information on the climate in May, visit the climate summaries page at


Percentage of average rainfall for May 2005 (recording sites shown with dots).

Difference from average air temperature in degrees Celsius for May 2005.

Difference from normal surface water temperatures (SSTs) in the seas around New Zealand. The New Zealand average SST was about +0.8 °C higher than normal in April, up slightly from March.

Global setting and climate outlook

Warming short lived

Difference from average global sea surface temperatures. Map courtesy of NOAA/Climate Diagnostics Centre.

Monthly values of the Southern Oscillation Index (SOI), a measure of the changes in atmospheric pressures across the Pacific, and the three month mean (black line).

While surface waters along the equator in the eastern Pacific warmed rapidly in late April and early May, hinting at a possible return to El Niño, these developments appear to have been a short-lived perturbation.

The Southern Oscillation Index (SOI) dropped slightly in May to –1.5, giving a three-month mean of –1.0. Despite the continuing negative SOI, the tropical Pacific is presently in a neutral state (no El Niño or La Niña). Conditions are likely to stay in the neutral range through winter and into early spring