Autumn 2002

Wednesday 5 June 2002

Sunny with below average rainfall in many areas, especially in the east
Above average rainfall in parts of Buller and Southland
Warm in Auckland, Waikato, Buller, Nelson and Central Otago

Autumn was sunny with below average rainfall in many regions. It was very dry, with less than 50 percent (half) of normal autumn rainfall in Gisborne, central Hawke’s Bay, central Marlborough, the Kaikoura coast and parts of Central Otago. Many areas in these eastern regions experienced one of their driest autumns on record. This was in contrast to the very wet unsettled summer earlier in the year. Autumn rainfall was above average in parts of Buller and Southland. Mean temperatures were above normal in Auckland, Waikato, Buller, Nelson and Central Otago, but near average elsewhere. The national average temperature of 13.5°C was 0.3°C above normal. Sunshine was above average in most eastern regions from Gisborne to north Canterbury, including Wellington and Nelson. It was cloudier than usual in parts of Northland, Auckland and south Canterbury.

Other features of the autumn were significant snowfall events in early April (on Mt Taranaki and Banks Peninsula) and late May (to low levels in Southland and Otago) and major southerly gales at the start and end of April and also late in May with high seas resulting in damage along some eastern coastlines and cancellation of ferry-crossings through Cook Strait. Extremes of temperature also occurred.

The autumn climate pattern was dominated by more depressions (‘lows’) than usual southeast of the South Island, with above average pressures over the southern ocean south of Australia. These features resulted in more frequent westerly winds over the North Island and more frequent southerlies over southern New Zealand.

Below average rainfall in many areas, especially in the east

Rainfall was less than 75 percent (three quarters) of normal in eastern areas from Gisborne to Central Otago, and Coromandel, Waikato, western Bay of Plenty, the west of the North Island from Manawatu to Wellington, Nelson, and parts of eastern Northland and Auckland. Rainfall was less than 50 percent (half) of normal in Gisborne, central Hawke’s Bay, central Marlborough, the Kaikoura coast and parts of Central Otago. Rainfall was at least 125 percent (one and a quarter) of normal in parts of Buller and Southland, and near average elsewhere.

Near or record low autumn rainfall was recorded at:

Location	Autumn rainfall (mm)	Percentage of normal	Year Records began	Comments
Pukekohe	199	60	1970	Lowest
Gisborne Airport	77	29	1905	Lowest
Napier Airport	69	30	1951	2nd lowest
Wellington Airport	129	49	1960	2nd lowest
Hanmer Forest	102	34	1905	2nd lowest
Kaikoura	104	41	1949	3rd lowest

Near record high autumn rainfall was recorded at:

Location	Autumn rainfall (mm)	Percentage of normal	Year Records began	Comments
Arapito, North Westland	811	142	1978	2nd highest

Warm in Auckland, Waikato, Buller, Nelson and Central Otago

Mean temperatures were 0.5 to 0.9°C above normal in Auckland, Waikato, Buller, Nelson and Central Otago, and near average elsewhere.

Sunny in many eastern regions

Sunshine and solar radiation totals were above average in most eastern regions from Gisborne to north Canterbury, including Wellington and Nelson. Totals were below normal in parts of Northland, Auckland and south Canterbury and near average elsewhere.

Near or record low autumn solar radiation was recorded at:

Location	Autumn Solar radiation (MJ/m2 / day)	Percentage of average	Year Records began	Comments
Timaru Airport	8.3	81	1991	Lowest

Highlights

Extreme temperatures

• The highest air temperature for the autumn was 31.9°C, recorded at Whakatu on 21 March. This was the highest autumn air temperature at Whakatu since measurements began in 1983.
• The lowest air temperature for the autumn was –7.0°C, recorded at Fairlie on 27 March.

High rainfall

• A ferocious rainstorm on 1 March produced rainfall totalling 98 mm in an hour at Egmont Village. There was also some serious flooding in parts of North Taranaki.

Thunderstorms

• Thunderstorms were frequent on the West Coast in March, occurring on 10 days.

Snowfall

• Cold southerlies on 2 April produced snowfall on Mt Taranaki, to its lowest level on record for the time of year. Snow also lay on the Desert Road, and in hill country areas on Banks Peninsula.
• Bitterly cold southwesterlies brought snowfall to near sea level in Otago and Southland from the 25–28 May. On the 26 May dozens of motorists were left stranded on SH1 north of Dunedin, which was closed for some hours due to snow and ice. Some inland Southland and West Otago roads were also closed because of snow, 30–40cm deep in places. Some schools closed. Power failures affected some areas. Snow lay a few centimetres deep in Dunedin, where day-time maximum temperatures reached only 3°C. Snow was still lying in the Mainiototo Valley on 31 May, where thousands of cattle and sheep where suffering from exhaustion due to the cold and lack of feed. Snow also lay on the North Island’s Desert Road on 28 May, but it remained open.

Strong winds and high seas

• Huge seas, generated by strong southeasterlies, battered eastern coastlines of both islands on the 3 and 4 April. Powerful waves smashed through walls of beachfront batches in Hawke’s Bay between Haumoana and Te Awanga south of Napier. Wellington’s southern coast road was closed by debris. Most Cook Strait ferry sailings were cancelled, affecting more than 2000 travellers. A 12-km stretch of SH1 south of Kaikoura was badly damaged and closed for 12 hours.
• Further high seas (with 5.5 to 9-metre waves) occurred with gale force southerlies through Cook Strait on the 29 April, resulting in the 8am fast-ferry from Wellington having to turn back and cancellations of other fast-ferry sailings for the day. The Inter-island ferry took 6 hours to cross.
• A maximum wind gust of 139 km/h from the southwest was recorded at Taiaroa Head during the morning of 3 May.
• Gale force westerlies affected Taranaki (where a roof was blown off a house) on 27 May and high winds in Waipukurau contributed to power cuts there. High winds occurred through Cook Strait on 28 May resulting in fast-ferry cancellations. Winds in Waikato (where there were thunderstorms) gusted to 100 km/h on the same day.

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.