Friday, 6 December 2002
Windy: warmer at first, then very cold Significant soil moisture deficits in parts of New Zealand by the end of November Sunny in many northern and eastern regions Rainfall well below average in Bay of Plenty Wet and unsettled in the southwest of the South Island Many extreme events
Spring commenced with a windier and warmer than normal September. However, along with the wind, very cold conditions for the time of year predominated for the rest of the season. This resulted in the coldest October–November period since 1978, with a mean temperature of 12.0°C, 1.0°C below normal. For the season overall, the national average temperature of 11.6°C was 0.5°C below normal. Mean temperatures were below normal in most places, especially King Country, the North Island’s central plateau, the Taupo–Rotorua area, and inland Southland.
Sunshine hours were above average in the north and east of both islands, especially Nelson, where it was the sunniest in over 50 years.
Rainfall was only 50 percent (half) of average in coastal areas of Bay of Plenty, and it was also drier than average in Northland, Gisborne, Marlborough, Nelson, and south Canterbury. Significant soil moisture deficits persist in central Marlborough (after five months with below normal rainfall), and have also developed in south Canterbury, northern and Central Otago, and parts of Northland and Bay of Plenty. Soil moisture, at the end of the season, was also well below average for the time of year in Gisborne, Hawke’s Bay and Nelson. In contrast, wet unsettled conditions prevailed in Fiordland, the Southern Lakes, and coastal Southland. Rainfall was also above normal in parts of north Canterbury.
Other features of the spring were:
- significant hailstorms in mid-September (Takaka and Wellington), late October (damaging strawberries and glass houses in Canterbury), and early November (ruining apple crops in Nelson),
- intense 2-day rainfall in mid-September (Milford Sound),
- severe northwesterly gales (Canterbury on 22 September, and the south and east of the North Island on 1 and 11 November),
- damaging frost in late September (Wairarapa, Hawke’s Bay and Gisborne), early October, and mid-November (Marlborough), and
- tornadoes in late October (Auckland and Canterbury).
The season began with persistent westerlies. However the October–November period was dominated by more depressions (‘lows’) than usual about and east of the Chatham Islands, with above average pressures in the north Tasman Sea, resulting in more frequent cold southwesterly winds over the country.
Below average temperatures in most regions
Mean temperatures were 1.0 to 1.5°C below average in some inland regions of the North Island, particularly King Country, the North Island’s central plateau, and the Taupo–Rotorua area, as well as inland Southland. Temperatures were 0.5 to 0.9°C below normal in most other North Island areas, as well as Buller and Westland, and slightly below average in most other regions. Mean temperatures were near average in coastal Marlborough.
Near or record low mean spring temperatures were recorded at:
| Location | Mean temperature (°C) | Departure from normal (°C) | Records began | Comments |
|---|---|---|---|---|
| Kaikohe | 12.7 | –0.8 | 1973 | 2nd equal lowest |
| Rotorua Airport | 11.1 | –1.1 | 1964 | Well below average |
| Taupo Airport | 10.1 | –1.0 | 1976 | 2nd equal lowest |
| Taumarunui | 11.3 | –1.5 | 1947 | 2nd lowest |
| Ettrick | 10.4 | –1.2 | 1985 | Well below average |
| Gore | 8.6 | –1.3 | 1971 | 2nd lowest |
Sunny in many northern and eastern regions
Sunshine and solar radiation totals were at least 110 percent of average in northern and eastern regions of both islands, and near average elsewhere.
Near or record high spring sunshine hours were recorded at:
| Location | Spring sunshine (hours) | Percentage of average | Year records began | Comments |
|---|---|---|---|---|
| Kaitaia Observatory | 629 | 113 | 1985 | Highest |
| Auckland | 630 | 115 | 1909 | Well above average |
| Gisborne Airport | 717 | 117 | 1905 | 2ndhighest |
| Nelson Airport | 716 | 115 | 1948 | 3rd highest |
| Christchurch Airport | 665 | 116 | 1949 | 3rd equal highest |
Record high spring solar radiation was recorded at:
| Location | Spring solar radiation (MJ/m2/day) | Percentage of average | Year records began | Comments |
|---|---|---|---|---|
| Kerikeri | 19.6 | 117 | 1988 | Highest |
| Whitianga Airport | 18.8 | 117 | 1990 | Highest |
| Te Puke | 17.8 | 118 | 1996 | Highest |
Well below average rainfall in Bay of Plenty
Rainfall was about 50 percent (half) of normal in coastal areas of Bay of Plenty. It was also drier than average in Northland, Gisborne, Marlborough, Nelson, and south Canterbury, all with rainfall less than 75 percent (three quarters) of normal.
Near or record low spring rainfall was recorded at:
| Location | Spring rainfall (mm) | Percentage of normal | Year records began | Comments |
|---|---|---|---|---|
| Rotorua Airport | 192 | 55 | 1964 | 2nd lowest |
| Taupo Airport | 155 | 65 | 1976 | 2nd lowest |
| Palliser | 89 | 41 | 1930 | Lowest |
| Waimate | 57 | 39 | 1898 | 2nd lowest |
Wet in the southwestern South Island
Rainfall was at least 125 percent (one and a quarter) of normal, with 10–15 more wet-days (rainfall totaling at least 1.0 mm) than average in Fiordland, the Southern Lakes, and coastal Southland. Rainfall was also at least 125 percent of normal in parts of north Canterbury. Totals were near average elsewhere.
Near record high spring rainfall was recorded at:
| Location | Spring rainfall (mm) | Percentage of normal | Year records began | Comments |
|---|---|---|---|---|
| Tiwai Point | 420 | 158 | 1970 | Highest |
Highlights
Extreme temperatures
- The lowest air temperature for the season was –7.4°C, recorded at The Chateau, Ruapheu, on 5 October. The only lower October air temperature on record there is -8.3°C in 1945.
- The highest air temperature for the season was 30.1°C, recorded at Murchison on 30 November. This was the highest spring air temperature on record at Murchison since measurements began in 1970.
Significant hailstorms and thunderstorms
- Heavy hail fell in central Takaka just before noon on 12 September, with hailstones reported as “pea-to-mothball size”, lying 10 cm deep in places.
- A localised, but rather heavy, hailstorm occurred over Wellington’s eastern suburbs (of Mirimar, Kilbirnie and Lyall Bay) at about 7 a.m. on 12 September, resulting in the temporary closure of the airport due to icy conditions on the runway. Pea-size hailstones lay a few centimetres deep in areas, some still present after 2 hours.
- Thunderstorms with large hail occurred in Canterbury on 27 October. Hailstones, some the size of golf balls and 50 cent pieces, occurred in the Hornby–Avonhead area, damaging numerous strawberry plants. Other damages reported were denting of vehicles and broken windows. Significant surface flooding occurred in the Hornby shopping area after the event. Up to 1,000 panes of glass were broken in seven glasshouses on one Christchurch tomato farm during the hailstorm.
- A spectacular display of lightning occurred over Northland, Auckland, and Coromandel during the night of 1–2 November, with almost 500 lighting flashes detected over Auckland and about 300 over both Whangarei and Whitianga.
- On 17 November hailstorms struck apple orchards in the Motueka area of Nelson province, some resulting in severe damage to crops. A few orchards lost 70–100 percent of their potential crop. Estimates of the losses in terms of export crops stood at $20 million.
Intense rainfall
- Heavy rainfall at Milford Sound totalled 459 mm for the 48 hours to 9 a.m. on 19 September, of which 315 mm occurred in 24 hours.
Severe gales
- Severe northwest gales buffeted parts of Canterbury on 22 September, resulting in damage to a number of properties. Wind gusts to 117 km/h were recorded at Rangiora and 115 km/h at Darfield.
- Gale force north-westerlies buffeted the lower North Island on 1 November, with a maximum gust of 130 km/h recorded at Kelburn, Wellington. Further high winds on the 11th resulted in a few lifted roofs in Wellington, Wairarapa, and Hawke’s Bay. Power was cut in some areas of Hawke’s Bay as tree branches damaged power lines.
Damaging frosts
- Damaging frosts occurred on three occasions: 15 September, 26 September and 5 October, affecting east coast areas of the North Island (Gisborne, Hawke’s Bay and Wairarapa) and Bay of Plenty. Frost-fighting equipment, such as water sprinklers, windmills and up to 40 helicopters, was used to counter potentially damaging frost in vineyards in parts of Hawke’s Bay during the night of 25/26 September. Some areas reported damage to 10–70 percent of Chardonnay, Pinot Noir and Merlot vines. Whakatu recorded a grass minimum of –7.3°C, the lowest there in September since records began in 1983, with a screen minimum of –2.0°C, the second lowest on record. The screen minimum at Whakatu near Hastings was –2.3°C on 5 October.
- Late spring frosts created potential for damage to grapevines throughout central Marlborough during the night of 17/18 November. An air minimum of –1.6°C was recorded at Blenheim Airport that night, the second lowest there in November since measurements began in 1941.
Tornadoes
- A tornado struck at Taitapu, near Lincoln, southeast of Christchurch on 27 October, damaging trees in the area, with another near Halswell on the same day. Tornado-like winds ripped roofing iron off a house, and toppled fences in Blockhouse Bay, Auckland, on the 25th. Another tornado was sighted in Auckland on 29 October.
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.