Climate Update 67 - January 2005

January

Climate

River flows

Soil moisture

Three-month outlook

Checkpoint

Backgrounder

Backgrounder

Backgrounder
Bleak December ends a turbulent year

Difference from mean sea level pressure (hectopascals) in December – the month was dominated by some of the strongest westerly and southwesterly wind flows on record. Map: Jim Renwick

The year 2004 will not be forgotten quickly. Extreme weather conditions, on many occasions unprecedented in the climate record, made it a hazardous year for weather and climate sensitive industries, and may have prompted revised assessments of natural hazard risk.

Checkpoint

Outlook and outcome – October 2004 to December 2004
Rainfall was normal or above in the southwest North Island and the east of both Islands, which was higher than predicted. The west of the South Island was drier than forecast. Rainfall was near normal elsewhere.
Air temperatures were average (as predicted) in the south west of the North Island, but lower than expected elsewhere in the country.
North Island river flows were normal or above normal, which was generally higher than predicted.

January

Climate Update is a summary each month of New Zealand’s climate, including soil moisture and river flows.
January 2005 – Number 67
December’s climate: Coldest December since 1945.
December’s river flows: River flows were higher than expected in many catchments.
Soil moisture levels: Wet conditions in the east from Hawke’s Bay to Southland.
Three-month outlook: Generally cool conditions except for average temperatures in the east of the North Island.

Climate

New Zealand Climate
Cold and wet December
New Zealand experienced the coldest December since 1945, with previously unrecorded low temperatures in many places.
Rainfall was well above average in the east from Hawke’s Bay to Southland, while conditions in Westland and Fiordland were drier than normal.
For more information on the climate in December, visit the climate summaries page at www.niwa.co.nz/ncc/cs/mclimsum_04_12
 
Percentage of average rainfall for December 2004 (recording sites shown with dots).

Three-month outlook

The outlook for January 2005 to March 2005
Lower than normal mean sea-level pressures to the south of New Zealand are expected, with stronger than normal west to southwest wind flow over the country. Sea surface temperatures around New Zealand are expected to be below average in January, but tending to average by March.
The average air temperature for the next three months is expected to be below the historical average everywhere except in the east of the North Island, where it is expected to be average.
Below normal or normal rainfall is expected in the north and east of the North Island.

River flows

River flows
Higher flows than expected in eastern regions
Streamflows were well above normal in the south and east of the South Island, below normal in the west, and normal or below normal in the north of the South Island. Normal to above normal flows in the North Island.

Percentage of average December streamflows for rivers monitored in national and regional networks. The contributing catchment area above each monitoring location is shaded. NIWA field teams, regional and district councils, and hydro-power companies are thanked for providing this information.

Soil moisture

High soil moisture levels in most areas
At the end of December, soil moisture levels were generally above average across the country, apart from near average conditions in Gisborne, Marlborough, and Kaikoura. Soils were very wet in the central and western North Island, and in Westland and Southland.
 
Soil moisture deficit in the pasture root zone at the end of December (right) compared with the deficit at the same time last year (centre) and the long-term end of December average (left).