Climate Update 99 - September 2007

September

August's climate

Global setting and climate outlook

Feature article

Feature article

Winter rainfall at Whangarei Airport

Exceptionally high rainfall in July 2007 that contributed most to the winter total, after a relatively dry period in the preceding months.

3–month rainfall totals for Whangarei Airport.

Winter temperatures were higher than normal as expected over much of the North Island, but unexpectedly low in the south of New Zealand.

August's climate

New Zealand climate in August

Rainfall (click to enlarge).

Temperature (click to enlarge).

August was windy at times with frequent disturbed southwesterlies, especially to the east, resulting in low rainfall in sheltered northern and eastern South Island regions, and normal or above normal rainfall in several other regions.
Temperatures were above normal over much of the North Island and near average over much of the South Island. The national average temperature of 9.1 ºC was 0.4 ºC above normal.

Global setting and climate outlook

Global setting and climate outlook
La Niña indicators strengthen

Difference from average global SST (click to enlarge).

Monthly SOI values (click to enlarge).

Conditions in the tropical Pacific are in a borderline La Niña state, with some strengthening of this phase of the El Niño-Southern Oscillation over the past month. There is a 60% chance of La Niña conditions developing in the equatorial Pacific during the spring (September–November) forecast period, with less than a 10% chance of El Niño conditions developing.

September

A monthly newsletter from the National Climate Centre.
September 2007 – Number 99
August – below normal rainfall in the north and east of the South Island; near or above normal rainfall in regions exposed to the west. Above average temperatures in the North Island; cold in the south. River and stream flows low in eastern regions and normal to above normal elsewhere.
Outlook for September to November – normal rainfall in the east of the North Island; normal or below normal rainfall elsewhere.