Winter 2001

Wednesday 5 September 2001

Below average rainfall in many regions, especially western Bay Of Plenty
Mixed temperatures, extremes of warmth and cold
Very sunny in Taranaki, Nelson and Westland

Mixed climatic conditions in winter resulted in a variety of extremes and contrasts. The season featured:

• Unusually low rainfall in western Bay of Plenty
• Variable temperatures in many areas
• Freezing mid-winter conditions and occasional low level snowfalls
• Very sunny conditions in Taranaki, Nelson and Westland

Seasonal rainfall was below average in many regions, including Taupo and most South Island hydro-lake catchment areas. Totals were extremely low in western Bay of Plenty, being less than 50 percent of normal. Rainfall was above average only in parts of south Taranaki and south Westland. Soil moisture continues to be lower than normal in central Marlborough, north Canterbury, and north Otago and Central Otago.

Winter began with a much warmer than average June, followed by a very cold frosty July, ending with rather mild August conditions. This combination resulted in near average winter temperatures overall throughout much of New Zealand. However, the winter was warmer than average in Wellington, Blenheim, and in most coastal areas of Southland and Otago, and colder than average in parts of Bay of Plenty, southern Hawke’s Bay and Westland. The national average temperature was 8.2°C, which was 0.1°C above the 1961–1990 normal.

It was very much sunnier than average in Taranaki, Nelson and Westland.

The overall winter climate pattern was the result of variable pressure anomalies over New Zealand, with no particular type dominating.

Below average rainfall in many regions, especially western Bay Of Plenty

Extremely low winter rainfall was recorded in western Bay of Plenty, with totals less than 50 percent of normal. It was also drier than average in many other regions, including eastern Northland, Waikato, Coromandel, the central North Island volcanic plateau, central Hawke’s Bay, Wellington, Golden Bay, northern and inland south Canterbury, and north Otago, all with totals between 50 and 75 percent of normal.

Unusually low winter rainfall was recorded at:

Location	Rainfall (mm)	% normal	Year records began	Comments
Hamilton, Ruakura	188	52	1905	3rd lowest
Tauranga Airport	170	44	1889	5th lowest
Te Puke	201	41	1973	Lowest
Rotorua	152	37	1899	Lowest
Taupo	159	65	1950	3rd lowest

Rainfall ranged from 110 to 120 percent of average in parts of south Taranaki and south Westland and was near average in other regions.

Near average temperatures overall for most areas

Mean winter temperatures were near average throughout much of New Zealand. However, they were at least 0.5°C above average in Wellington, about Blenheim, and in most coastal areas of Southland and Otago. Mean temperatures were around 0.5°C below average in parts of Bay of Plenty, southern Hawke’s Bay and Westland.

Very sunny in Taranaki, Nelson and Westland

Sunshine and solar radiation totals were at least 105 percent of normal in northern and western regions of both islands, including Gisborne and Canterbury. However, it was very sunny in Taranaki, Nelson and Westland, with totals exceeding 120 percent of normal. Most other regions experienced near average sunshine hours.

Near record high winter sunshine hours were recorded at:

Location	Sunshine (hr)	% normal	Year records began	Comments
New Plymouth Airport	490	123	1973	2nd highest
Hokitika	455	125	1913	3rd highest
Nelson Airport	561	121	1949	2nd highest

Highlights

Extreme temperatures

• The highest air temperature for the winter was 23.2°C, recorded at Dargaville on 22 August. The highest winter air temperature on record for Dargaville is 24.4°C.
• The lowest air temperature for the winter was -12.2°C, recorded at Hanmer Forest on 5 July. The lowest winter air temperature on record for Hanmer Forest is -13.2°C.

Fog

• Many sheltered Central Otago locations suffered not only severe frost during the first two weeks of July, but also freezing fog; some sites not seeing the sun for 14 days.

Southerly gales and snowfall

• Bitterly cold southerlies brought snowfall (a few centimetres deep) to sea level in many eastern South Island regions on 10 June, especially in Southland and Otago, temporarily closing Dunedin’s northern motorway. Gales affected Cook Strait, disrupting ferry services, snow and ice lay at the Rimutaka Hill summit north of Wellington and closed the Desert Road in the central North Island.
• High winds and heavy seas buffeted southern and eastern coasts on 28 and 29 July, creating 11-metre swells in Cook Strait. The Cook Strait fast ferry was forced to turn back to Wellington, and many other ferry sailings were cancelled, disrupting travel for thousands of passengers. Heavy snowfalls were recorded in most mountainous regions, and snow and ice closed Arthur’s Pass. Ruapehu ski field reported its largest snowfall in 20 years.
• A depression developed on a southerly front on 14 August and later deepened just east of Gisborne. The associated weather system produced extensive snowfall throughout the central North Island volcanic plateau on the 14th and 15th. Snowfall 30 cm deep was reported in Ohakune, the town being isolated by snow-closed roads. The Taupo to Napier highway was also closed. Snowfall 20 cm deep at Waiouru was reported as being the "biggest and deepest since 1974". At the same time southerlies up to violent-storm force (mean wind speeds to 117 km/h, and gusts to 189 km/h) occurred in Cook Strait. Huge swells and 11-metre waves resulted in the cancellation of ferry crossings on 15th August.

High rainfall

• Heavy rainfall, totalling as much as 150 mm, was reported in the Coromandel over the night of 30/31 August with surface flooding in some areas.

For further information, please contact:

Dr Jim Salinger – Principal Scientist, Climate
NIWA National Climate Centre – Auckland
Phone +64 9 375 2053
[email protected]

Stuart Burgess – Climatologist
NIWA National Climate Centre – Wellington
Phone +64 4 386 0569
[email protected]

Geoff Baird – Communications Manager
Phone +64 4 386 0543
[email protected]

Acknowledgement of NIWA as the source is required.