February 2002

Friday, 1 March 2002

Wet in the lower half of the North Island and North Canterbury Dry in the northern half of the North Island and parts of the South Island West Coast Warm and sunny on the West Coast of the South Island Cool and cloudy in the east

A contrasting mixture of weather conditions featured in the North and South Islands during February. Many districts on the lower half of the North Island, Taranaki and Hawke’s Bay received about twice their normal rainfall. Rainfall was also above average in north Canterbury and coastal Southland. At the same time, Waikato, western Bay of Plenty, Taupo, and parts of Northland and Central Otago all received less than half their than normal rainfall. Low rainfall in inland Southland over the past three months has produced significant soil moisture deficits in that region, with moderate deficits prevailing in Central Otago.

Overall it was much colder than normal with mean temperatures at least 1.0°C below normal in many areas, especially in the east from Gisborne to Otago. However, mean temperatures were about 1.0°C above normal on the West Coast. The national average temperature of 16.2°C was 0.8°C below the mean February temperature for the period 1961–1990, and the lowest for February since 15.1°C in 1993. There were relatively few very hot days. In the North Island the highest recorded maximum temperature was 29°C. In the South Island the highest recorded maximum temperature was 32°C.

The South Island West Coast and Southland continued to experience more sunshine than normal. Lower than normal sunshine hours persisted in the east, from Gisborne to Canterbury.

February’s climate pattern was dominated by more depressions (‘lows’) than usual in the Tasman Sea, and to the north and east of New Zealand, with above average pressures south of New Zealand. These features resulted in more frequent cold easterly and south-easterly winds in eastern New Zealand regions, especially over the South Island.

Wet in the lower half of the North Island and North Canterbury

Rainfall was about 200 percent (double) of normal in some districts in the lower half of the North Island, including Taranaki and Hawke’s Bay. Rainfall totalling more than 300 percent (three times) of normal on Great Barrier Island, Auckland was due to an isolated extreme rainfall event on 21 February. Above average rainfall, with totals at least 120 percent of normal, occurred in Coromandel, central Hawke’s Bay, the central North Island volcanic plateau, north Canterbury, and coastal Southland.

Near or record high February rainfall was recorded at:

Location	February rainfall (mm)	Percentage of normal	Year records began	Comments
Great Barrier Island	284	371	1977	2nd highest
Whakatu	130	266	1983	2nd equal highest
New Plymouth Airport	235	247	1944	2nd highest
Palmerston North Airport	119	199	1944	2nd highest

Dry in the northern half of the North Island and parts of the South Island West Coast and Central Otago

Rainfall was less than 50 percent of normal in Waikato, western Bay of Plenty, Taupo, and parts of Northland and Central Otago. And less than 75 percent of normal in Auckland, eastern Bay of Plenty, south Westland and Fiordland.

Extremely low February rainfall was recorded at:

Location	February rainfall (mm)	Percentage of normal	Year records began	Comments
Taupo Airport	7	9	1976	2nd equal lowest

Warmer on the West Coast of the South Island Cooler in most other regions, especially in the east

Mean temperatures were about 1.0°C above normal on the West Coast, but at least 1.0°C below normal in many other regions. They were at least 1.5°C below average in the east from Gisborne to Canterbury. Mean temperatures were near average in the Southern Lakes, and Southland.

Near record low mean February temperatures were recorded at:

Location	Mean temperature	Departure (°C)	Records began	Comments
Taupo Airport	15.4	–1.3	1976	3rd lowest
Castlepoint	16.0	–2.3	1972	3rd lowest
East Taratahi	15.6	–1.8	1973	3rd lowest
Whakatu	16.1	–2.0	1983	Equal lowest
Normanby	15.5	–1.2	1978	3rd lowest
Appleby	15.7	–1.9	1932	3rd lowest
Blenheim	15.9	–2.0	1933	2nd equal lowest
Blenheim Airport	16.1	–2.4	1941	2nd lowest
Kaikoura	14.5	–1.9	1964	2nd lowest
Christchurch Airport	14.9	–1.8	1954	2nd lowest

Mean daily maximum temperatures were well below average (by 2.0 to 3.5°C) in Hawke’s Bay, Wairarapa, Marlborough, and Canterbury.

Sunny in Westland and Southland, rather cloudy in the east

Sunshine and solar radiation totals were above 115 percent of average in Westland and about 110 percent of average in Southland. Lower than normal sunshine hours were recorded in eastern regions from Gisborne to Canterbury, including Wellington.

Near or record low February solar radiation was recorded at:

Location	January solar radiation (MJ m-2 / day)	Percentage of average	Year records began	Comments
Kaikoura	16.3	82	1969	2nd lowest
Winchmore	15.6	83	1960	2nd lowest
Timaru Airport	13.8	80	1992	Lowest

Highlights

Extreme temperatures

• The highest air temperature for the month was 31.7°C, recorded at Darfield on the 11th. The highest February air temperature on record in Darfield is 39.4°C.
• The lowest air temperature for the month was –1.6°C, recorded at Ettrick, Otago on the 16th. This was Ettrick’s lowest February air temperature since measurements began in 1985.

Huge swells and rough seas

• Feb. 6 – Huge 6 to 8-metre swells were generated in Cook Strait by a severe southerly storm off the coast east of the North Island. These resulted in ferry cancellations and forced a southern coast road to be closed in Wellington. Three people had to be rescued from the sea. Heavy 5-metre swells also affected Gisborne, where the Jody F Millenium, a log carrier, was grounded in rough conditions on a sand bar. Farther south, gales and 5-metre swells generated by the storm resulted in the sinking of five small boats in Lyttelton Harbour.
• Feb. 13–14 – Another depression resulted in gale force southerlies with huge 6 to 8-metre swells in Cook Strait. These resulted in fast-ferry cancellations.

Significant rainfall and flooding

• Feb 11–13 – High rainfall totalling 89 mm was recorded at New Plymouth Airport on the 11th, with thunderstorms during the afternoon. Further high rainfall totalling 85 mm was recorded for the 24 hours to 9 am on the 13th at Whakatu.
• Feb. 21 – Whitianga, on the Coromandel, and Great Barrier Island were flooded by torrential rainfall. Whitianga Airport recorded 71.8 mm in the three hours to 9 am. Rainfall on Great Barrier Island totalled a massive 233.5 mm in the six hours to 9 am that morning.

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.