Climate Update 36 - June 2002

June

Climate

River flows

Soil moisture

Three-month outlook

Checkpoint

Backgrounder

Backgrounder

Backgrounder

2002 rainfall to date
Rainfall so far this year has been lower than average in much of the north of the North Island and in parts of the north and west of the South Island. Some eastern and southeastern areas of the South Island have been wetter than average.

Total rainfalls for 1 January to 30 June 2002, shown according to decile rankings of all rainfalls for this period from 1972.
Update on the SOI
The mean Southern Oscillation Index (SOI) for May was -1.5, with the three month average now at about -0.9.

Checkpoint

Outlook and outcome – March to May 2002
Rainfall was below average as forecast in the east of the North Island. Southland and the northwest of the South Island had normal or above normal rain as expected. Rainfall was lower than expected in Waikato and Bay of Plenty, and in central South Island areas, including west Otago and south Westland.
Air temperatures were near normal in many districts, as predicted.

June

Climate Update is a summary each month of New Zealand's climate, including soil moisture and river flows.
June 2002 – Number 36
May’s climate: Drier than normal in many areas.
May’s river flows: Mostly below normal streamflows in May.
Soil moisture levels: Soil moisture levels rising.
Three month outlook: Drier than normal on eastern coasts; winter temperatures warmer than average overall.
Checkpoint: How well are we doing with our predictions?
Backgrounder: Past El Niños: spring temperature at Invercargill.

This issue of the Climate Update is available as a PDF.

Climate

New Zealand Climate in May 2002
Summer to winter in one month
May air temperatures were above average for the first three weeks, even summer-like at times. Then on 23 May a deep depression tracked across the South Island bringing thunderstorms to many western areas. This was followed by wintry southwesterlies which battered coastal Otago and Southland between 25 and 28 May, with freezing conditions and snow to low levels. Despite this, mean temperatures for the month were 1.5 °C or more above the historical average in parts of Central Otago and in many northern North Island areas.

Three-month outlook

The outlook for June to August 2002
An El Niño event which would influence New Zealand’s climate during spring and the 2002-03 summer is looking more likely now than it did a month ago.
For the immediate outlook period, June-August 2002 (winter), New Zealand temperatures are expected to be normal or above normal in all regions.
Rainfall is expected to be below average in all eastern regions, and near average elsewhere, except for normal or above normal rain in the west of the South Island.
Normal soil moisture levels and river flows are predicted for all regions of the country, exce

River flows

New Zealand River Flows in May 2002
Mostly below normal streamflows in May
May flows were very high in the far north and at record high levels in coastal Southland. Flows were below normal in most other places, with record lows in Hawkes Bay.

Soil moisture

Soil moisture on 31 May
Soil moisture levels rising
Although rainfall during May was lower than normal over much of the country, soil moisture levels in many areas improved during the month.