NIWA - National Climate Summary July 2008

NATIONAL CLIMATE CENTRE

Friday 1 August 2008

National Climate Summary – July 2008: Very wet and dull for most of country especially Marlborough, Canterbury and eastern Otago; Temperatures generally near or slightly above average

- Temperature: Near or slightly above average for most of the country;

- Rainfall: Well above normal rainfall (more than 200% of normal) in Marlborough, Canterbury, and eastern Otago; above normal (around 150% or more of normal) in Westland, Tasman, and the majority of the North Island;

- Sunshine: Below normal hours of bright sunshine recorded for most of country.

July was slightly warmer than average overall, and only slightly cooler than June, despite the cold spell which saw frosts as far north as Auckland and -9.1°C in Waiouru (a record low July minimum temperature for this location) in the second week of the month. The national average temperature of 8.3°C was 0.6°C above average. Kaikoura experienced a maximum temperature of 22.0°C on the 11th, its second highest temperature ever for the month of July.

Rainfall was well above normal (more than 200%) in Marlborough, Canterbury, and eastern Otago, with near record high July totals in many locations. Much of the rest of the country, with the exception of Southland and Gisborne, received above normal rainfall for July. In terms of other extremes, there were several storms during the month bringing a mixture snow, high winds, heavy rainfall and high seas to much of the country (see Highlights and Extremes section below). In the last week of the month New Zealand was hit by two intense storms which caused significant damage to property, resulted in several evacuations, and led to the deaths of four people (and one person still missing).

Further Highlights:

 The highest temperature during July 2008 was 22.0°C recorded at Kaikoura on the 11th. Waiouru, Motu (inland from Gisborne), and Culverden received record or near record low temperatures on the 7th (Waiouru and Motu) and the 15th (Culverden).

 The highest 1-day rainfall was 165.8 mm recorded at Paeroa on the 26th (the highest 1-day total at this location since records began in 1914).

 The highest wind gust for the month was 174 km/hr at Cape Reinga on the 26th.

 Of the five main centres, Auckland was the warmest and sunniest, Wellington was the wettest, Christchurch the coldest, and Dunedin the driest (or the least wet!).

Temperature: Mean temperatures were near or slightly above average for most of the country.

Rainfall: Rainfall was more than twice (200 percent) normal in Marlborough, Canterbury, and eastern Otago, and about one and a half (150%) times normal in Westland, Tasman, and the majority of the North Island (with the exception of Gisborne).

Sunshine: July totals of bright sunshine were below average (less than 90 percent of normal) throughout much of the country. Sunshine totals were well below average (less than 75 of normal) in parts of Northland, Taranaki, Wairarapa, Marlborough, and inland Canterbury.

For further information, please contact:

Dr Andrew Tait – Climate Scientist – NIWA National Climate Centre, Wellington,

Tel. (04) 386 0562 (work) or (027) 327 7948 (mobile); or

Dr James Renwick – Climate Scientist– NIWA National Climate Centre, Wellington,

Tel. (04) 386 0343 (work) or (021) 178 5550 (mobile)

TEMPERATURE: NEAR TO SLIGHTLY ABOVE AVERAGE IN MOST AREAS

The national average temperature of 8.3°C was 0.6 °C above average. Most locations around the country received near or slightly above average temperatures for the month, with Milford Sound’s mean temperature of 6.8°C being 1.6°C above normal for this location (the largest temperature departure from normal for the country). Fairlie, in South Canterbury, had an average July temperature of only 1.7°C which was 1.9°C cooler than normal.

RAINFALL: WELL ABOVE NORMAL FOR MOST OF COUNTRY

July rainfall totals were above normal over most of New Zealand. The only areas to escape the high rainfall totals were coastal Gisborne and Southland. Marlborough, Canterbury, and eastern Otago received more than twice (200%) their normal July totals, while Westland, Tasman, and the majority of the North Island received about 150% of normal rainfall.

Near or record high July rainfall totals were recorded at:

Location July

rainfall total (mm) Percentage

of normal Year

records began Comments

Stratford 442 208 1938 Third highest

Paeroa 416 275 1914 Highest

Wallaceville (Upper Hutt) 326 232 1924 Highest

Hanmer Forest 284 248 1905 Third highest

Auckland (Owairaka) 249 170 1949 Second highest

Pukekohe 248 186 1963 Third highest

Auckland Airport 215 157 1962 Third highest

Paraparaumu Airport 210 207 1945 Fourth highest

Winchmore 182 281 1947 Highest

Nelson Airport 166 198 1941 Second highest

Christchurch Airport 165 230 1944 Third highest

Blenheim 153 210 1927 Third equal highest

Darfield 148 196 1920 Fourth highest

Culverden 132 216 1915 Second highest

Dunedin Airport 123 249 1963 Second highest

Timaru Airport 116 262 1957 Third highest

SUNSHINE: BELOW AVERAGE HOURS OF BRIGHT SUNSHINE FOR ALL OF COUNTRY

July totals of bright sunshine were below average (75 to 90 percent of normal) throughout much of the country. The only location to receive normal sunshine hours for July was Southland. Sunshine totals were well below average (less than 75 percent of normal) in parts of Northland, Taranaki, Wairarapa, Marlborough, and inland Canterbury.

Near or record low July sunshine hours were recorded at:

Location July

sunshine (hours) Percentage

of normal Year

records began Comments

Mt Cook, The Hermitage 41 55 1930 Lowest

Stratford 79 66 1963 2nd lowest

Martinborough 75 73 1968 3rd lowest

Kaitaia 85 57 1951 2nd lowest

Motueka 89 60 1965 Lowest

JULY’S CLIMATE IN THE FIVE MAIN CENTRES

All the main centres received near to slightly above average temperatures for July, with Auckland the warmest. Rainfall was well above normal for Auckland, Wellington (the wettest of the main centres), Christchurch, and Dunedin (the driest – or least wet! – of the main centres) and above normal for Hamilton. All of the main centres received below normal sunshine hours for July, with the sun peeping through the cloud most often in Auckland and least often in Dunedin.

July 2008 main centre climate statistics:

Location July

mean

temp.

(°C) Dep.

from normal

(°C) July

rainfall

(mm) % of

normal July

Sunshine

(hours) % of

normal

Auckland 11.1a 0.3 Average 249a 170 Well above normal 113c 87 Below normal

Hamilton 9.2 0.7 Above average 173 126 Above normal 101d 83 Below normal

Wellington 9.2 0.4 Average 252 184 Well above normal 94 80 Below normal

Christchurch b 6.5 0.7 Above average 165 230 Well above normal 97 79 Below normal

Dunedin 7.0 0.4 Average 144 215 Well above normal 80 79 Below normal

a Owairaka b Christchurch Airport c Mangere d Ruakura

HIGHLIGHTS AND EXTREME EVENTS

 Temperature

The highest temperature during July 2008 was 22.0ºC recorded at Kaikoura on the 11th, the second equal highest July temperature on record (since 1964) at this location. The North Shore recorded 20.2°C on the 19th, which was the third highest July temperature at this location.

There were freezing temperatures across the country on the 9th, with negative numbers recorded from Auckland (-1°C) to Queenstown (-4°C). The unusual sight of frost in Auckland was seen for two days in a row on the 8th and 9th.

Near record low extreme minimum daily air temperatures were recorded at:

Location Extreme minimum

temperature

(ºC) Date of extreme temperature Year

Records

began Comments

Waiouru -9.1 7th 1962 Lowest

Motu (west of Gisborne) -7.1 7th 1991 Lowest

Culverden -6.0 15th 1983 Second lowest

 High winds and tornadoes

Gale force winds in the Cook Strait led to the cancellation of interisland ferry services on the 6th and strong winds in Christchurch also blew down several power poles.

Wind gusts along the east coasts of the North and South Islands reached 120km/hr overnight on the 8th.

High winds on the 22nd damaged property in the Taranaki region. There were also reports of a small tornado in coastal Taranaki. Along Auckland's west coast gusts reached 105km/hr.

Wind gusts of between 100km/hr and 110km/hr buffeted both the Hauraki Gulf and Manukau Heads on the 23rd. Further south, at Golden Valley west of Tauranga, gusts of up to 100km/hr were recorded.

Northland experienced wind gusts of up to 174km/hr on the 26th bringing down trees and power lines as the storm made landfall. Thousands of homes were without power in the region. Power was also cut to 53,000 homes in Rodney, Waitakere and the North Shore. There were another 7000 without power in Auckland in Howick, Otara, Clevedon, Mangere and parts of Waiheke Island. Gusts in Auckland Harbour reached 125km/hr on the 26th. Hundreds of trees were brought down and several roofs were blown off by high winds in Te Aroha, in the eastern Waikato.

Winds of around 80km/hr hit Tauranga between 4am and 5am on the 30th and a tornado struck Tauranga and Mt Maunganui around 9am lifting roof tiles and smashing windows.

Near record high extreme wind gusts were recorded at:

Location Extreme wind gust speed

(km/hr) Date of extreme gust Year

Records

began Comments

Cape Reinga 174 26th 1974 Fourth highest

Awakino (Taranaki) 147 26th 2005 Highest

Baring Head (Wellington) 143 29th 1991 Highest

Brothers Island (Cook Strait) 143 29th 1997 Highest

Mokohinau Island (Northland) 124 27th 1994 Second highest

Nelson 119 30th 1972 Highest

Warkworth 115 26th 1973 Fourth equal highest

Paeroa 115 26th 1993 Highest

Awakino (Taranaki) 115 31st 2005 Third highest

Dargaville 108 26th 1998 Second highest

Auckland Airport 107 27th 1971 Fourth highest

Lincoln 100 5th 1999 Highest

- Heavy rain and flooding

The area around Mt Taranaki received 100mm of rain in the 24 hours to 6am on the 9th, and 60mm also fell in Milford Sound. Lower Hutt received 26mm of rain between 4am and 6am on the 9th.

32mm of rain fell within a few hours at Nelson airport on the morning of the 11th and even heavier rains may have come down in the surrounding hills. A large slip on Rocks Road, SH6 was cleared enough to allow cars through by the afternoon. The heavy rain and flooding in Nelson caused sewage to overflow into the harbour.

A river burst its banks on the 26th near the township of Panguru, on the northern side of Hokianga Harbour, and up to 35 people had been evacuated and roads throughout Northland were closed by flooding. The Kauaeranga River in the Coromandel also broke its banks and flooded the highway.

More than 160mm of rain fell in parts of the Coromandel overnight on the 29th resulting in parts of Hikuai and Pauanui on State Highway 25 being under more than a metre of water. The Karangahake Gorge SH2 between Paeroa and Waihi was flooded with water about 30cm deep, SH25 south of Whitianga was flooded with water 1m deep and unpassable, and Kaihikatea Road Dairy Flat was flooded. Slips and downed trees caused closures of several other roads. One North Shore home has been completely destroyed in a slip, with another 14 homes at risk.

Tauranga and the Western Bay of Plenty received approximately 45mm of rain from 9pm on the 29th to 5pm on the 30th. Whakatane received around 22mm of rain and Rotorua received approximately 14mm of rain in that time. A number of roads to the west of Gisborne were closed by surface flooding.

A state of emergency was declared by Marlborough District Council on the 30th due to extensive surface flooding. The storm knocked out an important water pipeline in Nelson. Picton police and volunteers sandbagged the waterfront in an effort to save the town from flooding. Severe flooding in the small South Island town of Sefton meant that 12 people had to be evacuated and spent the night in the local school hall.

The cost of the storm on the country is estimated to be more than $10 million.

One person drowned while attempting to cross a swollen stream near Kawakawa in Northland. Another person is missing, presumed dead.

Near record high extreme 1-day rainfall totals were recorded at:

Location Extreme 1-day rainfall

(mm) Date of extreme rainfall Year

Records

began Comments

Paeroa 165.8 26th 1914 Highest

Cheviot 146.8 30th 1983 Highest

Kaikoura 143.8 30th 1898 Highest

Ngawi (Cape Palliser) 128.2 30th 1930 Highest

Okuti (Banks Peninsula) 125.1 28th 1916 Highest

Hanmer Forest 121.2 30th 1906 Second highest

Paeroa 119.2 29th 1914 Fourth highest

Takaka 111.2 10th 1986 Fourth highest

Rangiora 107.6 30th 1891 Highest

Tauranga Airport 91.0 29th 1910 Third highest

Hicks Bay (East Cape) 88.4 29th 1955* Third highest

Tarapounamu (near Lake Waikaremoana) 79.8

30th 1969

Highest

Little Akaloa (Banks Peninsula) 79.4 28th 1912 Third highest

* includes Te Araroa rainfall data

 High seas

Huge waves on top of swells of more than 6m (up to 9m at Raglan) battered the North Island's west coast on the 23rd as a severe storm crossed the country. A man was plucked to safety from raging seas off the Kapiti Coast.

A canoeist drowned while paddling in stormy seas off Mt Maunganui on the 26th. Two other people died after the fishing boat they were on ran aground east of Opotiki.

Residents at Amberley Beach, about 50km north of Christchurch, were evacuated ahead of a high tide on the 31st but the high waters did not flood the settlement.

- Snowfall

Snow fell as far north as the Kaimai Ranges in the Waikato on the 5th while hail fell in Wanganui, Taranaki and Auckland on the same day. Sleet was reported in New Plymouth, Palmerston North and Wellington. Snow also fell in Queenstown (up to 18cm), Dunedin, Ashburton and Christchurch. Several roads were closed by snow or ice, including SH3 southeast of Hawera, the Napier-Taihape Rd, SH49 between Waiouru and Ohakune, SH1 between Rangipo and Waiouru, and several South Island roads including the main road to Akaroa.

Heavy snow on the 26th closed the Desert Rd and Napier to Taihape road in the central North Island.

Snow fell to depths of around 20cm in Temuka and elsewhere in inland Canterbury on the 31st.

- Thunder and lightning

More than 7500 lightning strikes were recorded on the South Island's West Coast on the 2nd, with 1100 in one hour alone, and power was knocked out for a short time. Around another 2200 strikes were recorded on the 5th, mostly along the west coast of both islands.

Northern and western parts of the North Island experienced a total of 25,000 lightning strikes from midnight on the 18th to 6pm on the 20th.

ENDS