September's climate

New Zealand climate in September 2005

Temperature (click to enlarge).

Rainfall (click to enlarge).

September temperatures were above average – the third consecutive month of warmer than normal conditions – in spite of a cold outbreak in the third week of the month. Rainfall was low in most places, but especially around Nelson, where the lowest rainfall for 70 years was recorded.

The warm, dry conditions were the result of frequent anticyclones to the east of the country which gave periods of northerlies over the North Island.

For more information on the climate in September, visit the climate summaries page at www.niwa.co.nz/ncc/cs/mclimsum_05_09

Low soil moisture in the east of the south

 

Soil moisture (click to enlarge).

Although less than normal, September rainfalls kept topsoils wet in most places. However, total moisture storage in east coast South Island soils was below average at the end of the month, particularly in coastal and south Canterbury, Otago, and parts of Marlborough.

 

Low river and stream flows

 

River flows (click to enlarge).

River flows were below average nearly everywhere.

July 2005 to September 2005: the climate we predicted and what happened

 

(click to enlarge).

Rainfall

Lower than normal rainfall in the north and east of the North Island was in line with predictions. The South Island was drier than expected.


 

(click to enlarge).

Air temperature

Air temperatures were above average in the North Island and north of the South Island as expected, but higher than predicted in the south of the country.


 

(click to enlarge).

River flows

Streamflows were lower than normal in the east of the country, as was signalled in the forecast, but lower than expected elsewhere.


The three outcome maps give the tercile rankings of the rainfall totals, mean air temperatures, and mean river flows that eventuated from July to September, in comparison with the forecast conditions.

As an approximate guide, middle tercile rainfalls typically range from 80 to 115% of the historical normal, and middle tercile temperatures range about the average by plus or minus 0.5 °C.