Thursday 1 August 2002
Well below average rainfall over much of the South Island Average or above average rainfall over the North Island
Rather mild in the North Island and northern South Island
Rather sunny in the far south
Above average to average rainfall in the North Island was accompanied by very dry conditions in much of the South Island in July. The driest regions in the South Island were Nelson, Marlborough, Canterbury and Central Otago, with totals less than 25 percent (quarter) of average. Rainfall at Lauder, Central Otago, totalled just 1 mm.
Most North Island regions experienced average or above average rainfall. Totals were 200 percent (double) or more of average in parts of central Hawke’s Bay. It was also wet in parts of eastern Northland, Coromandel, Taupo and much of the eastern North Island from Gisborne to Wairarapa. On the 12 the Waikato River overflowed at Mercer, flooding many nearby farms already saturated by weeks of wet weather.
The month was rather mild (with less frost than usual) throughout much of the North Island and northern South Island, overnight temperatures being much higher than usual. Temperatures were near average in most other areas. The national average mean temperature of 8.0°C was 0.3°C above normal.
Sunshine totals were near average in many areas. Southland, Otago, Buller and Westland were sunnier than normal. Cloudier than usual skies prevailed in the south and west of the North Island and eastern South Island from Kaikoura to Central Otago.
Over the North Island, July’s climate pattern was dominated by the passage of three depressions (‘lows’) that tracked east from the mid Tasman Sea. Over the South Island, anticyclones were a little more frequent than average in the south. This pattern produced more frequent onshore easterly winds from Gisborne to Canterbury.
Below average rainfall over much of the South Island
Rainfall was well below average over much of the South Island, with totals less than 25 percent of average throughout much of Nelson, Marlborough, Canterbury and Central Otago, and less than 50 percent of average in most other northern and eastern regions. Rainfall was less than 75 percent of average in Westland and western Southland, but near normal in Fiordland.
Near or record low July rainfall was recorded at:
| Location | July rainfall (mm) | Percentage of normal | Year records began | Comments |
|---|---|---|---|---|
| Reefton | 41 | 22 | 1961 | 3rd lowest |
| Motueka, Riwaka | 16 | 10 | 1943 | Equal lowest |
| Nelson Airport | 17 | 19 | 1941 | 3rd lowest |
| Appleby | 16 | 17 | 1932 | 3rd lowest |
| Blenheim Airport | 18 | 25 | 1941 | 3rd lowest |
| Winchmore | 19 | 28 | 1947 | 3rd equal lowest |
| Lauder | 1 | 5 | 1943 | Equal lowest |
| Clyde | 6 | 22 | 1983 | 2nd lowest |
| Ettrick | 6 | 15 | 1985 | Lowest |
| Tiwai Point | 36 | 38 | 1970 | 3rd lowest |
Average or above average rainfall totals over the North Island
Rainfall totals were 200 percent (double) or more of average in parts of central Hawke’s Bay, and at least 125 percent of average in parts of eastern Northland, Coromandel, Taupo and much of the eastern North Island from Gisborne to Wairarapa. Other North Island regions experienced near average rainfall.
High July rainfall was recorded at:
| Location | July rainfall (mm) | Percentage of normal | Year records began | Comments |
|---|---|---|---|---|
| Hicks Bay | 259 | 191 | 1991 | Highest |
| Napier Airport | 187 | 236 | 1951 | Well above normal |
Rather mild in the North Island and Northern South Island
Mean temperatures were 1.0 to 1.5°C above normal throughout much of the North Island, Marlborough and Nelson. However, they were near average elsewhere. North Island overnight minima were 2°C above normal in many areas, due to frequent cloudy nights.
Near record high mean July temperatures were recorded at:
| Location | Mean temperature | Departure (°C) | Records began | Comments |
|---|---|---|---|---|
| Tauranga Airport | 11.1 | +1.5 | 1913 | 3rd highest |
| Whakatane Airport | 10.0 | +1.5 | 1976 | 3rd highest |
| Turangi | 8.1 | +1.9 | 1968 | 3rd highest |
| Farewell Spit | 10.5 | +1.6 | 1971 | 3rd highest |
| Nelson Airport | 8.2 | +1.5 | 1943 | 3rd highest |
Rather sunny in the far south
Sunshine and solar radiation totals were near average in many areas. However, they were at least 130 percent of average in coastal Southland and at least 110 percent of average in Otago, Buller and Westland. Totals were less than 90 percent of average in the south and west of the North Island and eastern South Island from Kaikoura to Central Otago.
Near record high July sunshine hours were recorded at:
| Location | July sunshine (hrs) | Percentage of normal | Records began | Comments |
|---|---|---|---|---|
| Invercargill Airport | 122 | 145 | 1932 | 3rd equal highest |
Near or record low July solar radiation was recorded at:
| Location | July solar radiation (MJ/m2/day) | Percentage of normal | Year records began | Comments |
|---|---|---|---|---|
| Wanganui, Spriggens Pk | 5.4 | 80 | 1996 | Lowest |
| Timaru Airport | 4.0 | 73 | 1984 | Lowest |
Highlights
Extreme temperatures
- The highest air temperature for the month was 22.0°C recorded at Kaikoura on the 21st. The highest July air temperature on record at Kaikoura is 22.3°C.
- The lowest air temperature for the month was –9.8°C, recorded at Mt. Cook on the 18th. The lowest July air temperature on record there is -12.8°C.
Large hail
- On 3 July a 30-minute hail-storm struck Massey, west Auckland, from about 9.30 am, with some hail stones as large as golf balls.
High rainfall
- Surface flooding closed SH30 between Te Kuiti and Mangakino on the 8th. Three houses near Te Awamutu were evacuated due to flooding a few days earlier on the 5th.
- High rainfall totals, up to 100 mm, were recorded at sites in eastern Northland and Auckland on the 11th. Serious flooding occurred around Kaukapakapa north of Auckland. Farther south, the Waikato River overflowed at Mercer on the 12th, flooding 50% of 20 nearby farms, already saturated by weeks of wet weather.
Snowfall
- Snowfall on the 15th resulted in the closure of the North Island’s Desert Road, where 30 motorists had to be rescued by the army, as well as parts of SH47 through National Park and SH5 between Taupo and Napier (where 3 cm of snow lay). Snow lay 14 cm deep at Waiouru and 30 cm deep elsewhere.
High winds
- Gale-force south-southeasterlies with high seas and gusts to 160 km/h occurred through Cook Strait on the 14th, resulting in delays for over 1500 ferry passengers.
- Storm-force northeasterlies battered Cape Reinga on the 22nd, with gusts to 183 km/h, the highest gust there for any month since records began in 1974.
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.