July 2003
Friday, 1 August 2003
Sunshine: More than normal sunshine across the country, except for Auckland
Rainfall: Below average in most regions, especially Bay of Plenty, Marlborough and Nelson; wet along the Southland coast
Temperatures: Below average in most places and frostier than normal in many areas
July was colder, sunnier, and more settled and frosty than average, with well below average rainfall in most areas, especially parts of Marlborough and Nelson where July was the driest in more than 60 years of measurement. A severe snowstorm swept the country over 4–5 July. The July climate patterns were associated with more anticyclones (‘highs’) than average over New Zealand and in the Tasman Sea. These produced frequent days of light winds and clear settled conditions with cold nights.
Highlights:
- July 2003 temperatures ranged from a low of –14.8°C, recorded at Tekapo on the 13th, to a high of 18.3°C, recorded at Hanmer Forest on the 16th. This was Tekapo’s 2nd equal lowest July air temperature on record (measurements commenced in 1925).
- A very cold southerly outbreak brought significant snowfall to sea level in the eastern South Island on 4–5 July, with heavy snowfall settling down to 300–500 m in the central and eastern North Island on the 5th. Severe overnight ground frosts followed, especially in the South Island.
- The third week of July was very calm and anticyclonic with five to seven consecutive days of severe frosts in many inland areas.
- Rainfall and days with strong winds were below average in all the four main centres. Temperatures were below average in Christchurch, and near average in Auckland, Wellington and Dunedin. Sunshine hours were above average in Wellington, Christchurch and Dunedin. Totals were much lower than usual in Auckland.
Rainfall
It was rather settled, with rainfall less than 50 percent (half) of average in parts of Bay of Plenty, King Country, Taupo, the central North Island Plateau, Hawke’s Bay, Wellington, the South Island West Coast, Marlborough, Nelson, and coastal areas of both south Canterbury and Otago. Rainfall was also below average in most other regions. Totals were above average along the Southland coast.
Temperatures
Mean and minimum temperatures were below average over much of New Zealand. However, mean temperatures were above average in inland and Central Otago. The July national average temperature of 7.3°C was 0.4°C below normal. There were more ground and air frosts than normal in many areas, especially in the south and west of the North Island, including the Central Plateau, and parts of the north and east of the South Island. The frostiest periods, often with severe ground frost, occurred on July 6, 7, 12–14 and 20–26. Severe ground frost (–6.0°C or lower) occurred somewhere in New Zealand on most days of the month. High winds were largely absent.
Sunshine
Sunshine hours were above average in most regions, especially from Wairarapa to Otago, and in central regions from Wanganui to Westland, including Nelson and Wellington. Totals were well below average in Auckland.
Below average rainfall in most regions
Rainfall was less than 50 percent (half) of average in Bay of Plenty, King Country, Taupo, the central North Island Plateau, Hawke’s Bay, Wellington, the South Island West Coast, Marlborough, Nelson, and coastal areas of both south Canterbury and Otago. Totals were less than 75 percent (three-quarters) of average in most other regions.
Near or record low July rainfall was recorded at:
| Location | July rainfall (mm) | Percentage of normal | Records began | Comments |
|---|---|---|---|---|
| Kawerau | 30 | 19 | 1954 | Lowest |
| Rotorua Airport | 23 | 18 | 1964 | Lowest |
| Taupo Airport | 23 | 27 | 1976 | Lowest |
| Turangi | 33 | 22 | 1968 | 2nd lowest |
| Whakatu | 33 | 33 | 1983 | 3rd lowest |
| Hokitika Airport | 87 | 38 | 1964 | 3rd lowest |
| Motueka, Riwaka | 21 | 13 | 1943 | 3rd lowest |
| Nelson Airport | 9 | 10 | 1941 | 2nd lowest |
| Nelson, Appleby | 9 | 9 | 1932 | 3rd equal lowest |
| Blenheim Airport | 11 | 15 | 1941 | Lowest |
| Cape Campbell | 20 | 26 | 1988 | 2nd lowest |
| Timaru Airport | 8 | 17 | 1957 | 2nd equal lowest |
Rainfall was at least 120 percent of average along the Southland coast, and near average in much of Northalnd, Manawatu, Horowhenua, Southern Lakes, Central Otago, and inland Southland.
Below average temperatures in most places
Mean temperatures were at least 0.5°C below average throughout much of the North Island and northern half of the South Island, scattered areas being 1.0 to 1.5°C below average. They were about 0.5°C above average in inland and Central Otago.
Mean daily maximum temperatures were about 2.0°C above average in western and Central Otago. Mean daily minimum temperatures were 1.0 to 2.0°C below average throughout much of New Zealand.
Near or record low mean July temperatures were recorded at:
| Location | Mean temperature | Departure from average (°C) | Records began | Comments |
|---|---|---|---|---|
| Whakatu | 6.6 | –1.8 | 1983 | Lowest |
| East Taratahi | 6.1 | –1.3 | 1972 | 3rd lowest |
Near or record low mean daily minimum July temperatures were recorded at:
| Location | Mean temperature | Departure (°C) | Records began | Comments |
|---|---|---|---|---|
| East Taratahi | 0.0 | –2.7 | 1972 | 2nd lowest |
| Whakatu | 0.9 | –2.2 | 1983 | Lowest |
| Westport Airport | 3.0 | –1.5 | 1937 | 3rd equal lowest |
| Blenheim Airport | –0.3 | –1.7 | 1941 | 3rd equal lowest |
| Christchurch Airport | –0.9 | –1.7 | 1954 | 3rd equal lowest |
The frequent anticyclonic conditions produced clear nights with more days of frost, especially in the south and west of the North Island, including the Central Plateau, Nelson, and Canterbury. Some locations in these regions experienced air and ground frost on least 5 to 10 days more than average, with some severe occurrences. Some statistics on days of frost follow:
Well above average numbers of days with ground frost were recorded at:
| Location | Days with ground frost | Departure from normal | Records began | Comments |
|---|---|---|---|---|
| Waiouru | 25 | +8 | 1960 | Highest |
| Levin | 22 | +10 | 1921 | 2nd equal highest, most since July 1971 |
| Paraparaumu Airport | 19 | +8 | 1953 | Highest |
| Rangiora | 25 | +8 | 1965 | Highest |
| Christchurch Airport | 25 | +6 | 1954 | 2nd equal highest |
| Christchurch Gardens | 27 | +8 | 1864 | 2nd equal highest. Highest since 1952 |
| Balclutha, Finegand | 25 | +8 | 1964 | Highest |
Sunny in most regions
Sunshine totals were well above average (at least 120 percent of normal) in many eastern regions from Wairarapa to Otago, and in central regions from Wanganui to Westland, including Nelson and Wellington, and at least 110 percent of normal in most other regions. Well below normal sunshine occurred in Auckland.
Well above average July sunshine hours were recorded at:
| Location | July sunshine (hours) | Percentage of normal | Records began | Comments |
|---|---|---|---|---|
| Paraparaumu Airport | 162* | 133 | 1953 | 4th highest |
| Wellington, Kelburn | 153 | 139 | 1928 | 4th highest |
| Hokitika Airport | 148 | 123 | 1964 | Well above average |
| Nelson Airport | 195 | 126 | 1949 | 3rd highest |
| Dunedin, Musselburgh | 134 | 141 | 1948 | 4th highest |
* missing 28 July
Fewer windy days
There were fewer days with strong winds than average in July over much of New Zealand. This was particularly noticeable during the last few weeks.
Some wind gust statistics are:
| Location | July days with wind gusts ≥ 60 km/h | Departure from average |
|---|---|---|
| Auckland Airport | 2 | –5 |
| Hamilton Airport | 0 | –2 |
| Wellington, Kelburn | 12 | –4 |
| Nelson Airport | 0 | –2 |
| Christchurch Airport | 2 | –1 |
| Dunedin Airport | 5 | +1 |
July climate in the four main centres
July rainfall was below average in all the main centres. Dunedin was the driest centre, receiving only 27 mm of rain. Mean temperatures were below average in Christchurch, and near average in the other three centres. Wellington was the sunniest. Sunshine hours were also above average in Christchurch and Dunedin. Auckland received much less sunshine than normal.
| Auckland* | Wellington | Christchurch | Dunedin | |
|---|---|---|---|---|
| July mean temp. (°C) |
10.3 | 8.4 | 5.9 | 6.4 |
| Dep. from normal (°C) |
–0.2 | –0.1 | –0.4 | –0.1 |
| Near average | Near average | Below average | Near average | |
|
|
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| July rainfall (mm) | 113 | 64 | 47 | 27 |
| % of normal | 81 | 45 | 61 | 39 |
| Below average | Below average | Below average | Well below average | |
|
|
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| July sunshine (hours) | 86 | 153 | 140 | 134 |
| % of normal | 66 | 139 | 115 | 141 |
| Well below average | Well above average | Above average | Well above average | |
*Mt Albert
Highlights and extreme events
- July 2003 temperatures ranged from a high of 18.3°C, recorded at Hanmer Forest on the 16th, to a low of –14.8°C, recorded at Tekapo on the 13th. This was Tekapo’s 2nd equal lowest July air temperature on record (measurements commenced in 1925).
- A very cold southerly outbreak brought significant snowfall to sea level in the eastern South Island over the 4th and 5th of July, with heavy snowfall settling down to 300–500 m in the central and eastern North Island on the 5th. Snow flurries occurred to sea level in parts of the western north Island, and also in the east as far north as Napier. Snow settled to depths to 50 cm in the western Hawke’s Bay high-country, 30 cm in the Gisborne high-country, 30 cm in the Manawatu about and east of the Gorge, 35 cm on the Rimutaka Summit Road north of Wellington, 20–35 cm in inland Canterbury, and 10 cm in some inland areas of south Taranaki and Southland, with a few centimetres to sea level in many eastern South Island districts. Snow covered roads were treacherous, leaving most high-country roads closed. Numerous motorists and travellers were stranded, especially on the Desert Road (where some truck drivers stayed overnight in their cabs) and at Norsewood. Power was cut to more than 10,000 homes in the central and eastern North Island at the height of the storm, and many rural schools in both islands were closed. Dunedin, Invercargill and Queenstown airports were all closed for a period during the event, due to icy runways. South Island maximum temperatures ranged from just 1 to 5°C in many eastern areas south of Kaikoura on the 4th and 5th.
- Severe overnight ground frosts occurred in the fine weather that followed, especially in the South Island.
- Severe frosts resulted in near or record low minimum July air temperatures at:
| Location | Min. (°C) | Date | Records began | Comments |
|---|---|---|---|---|
| East Taratahi | –5.9 | 7 | 1972 | Lowest |
| Ranfurly | –11.6 | 5 | 1975* | Lowest |
| Dunedin Airport | –8.6 | 13 | 1963 | Lowest |
| Lauder | –9.4 | 5 | 1982 | 2nd equal lowest |
*Incomplete record
- Near or record low grass minimum July temperatures were recorded at:
| Location | Grass min. (°C) | Date | Records began | Comments |
|---|---|---|---|---|
| East Taratahi | –9.3 | 14 | 1972 | Lowest |
| Whakatu | –9.0 | 7 | 1983 | Lowest |
| Rangiora | –10.8 | 13 | 1965 | 2nd lowest |
| Christchurch Airport | –10.3/–11.5 | 7/13 | 1954 | Lowest |
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.