Warm; extremely cloudy and wet in the far north, extremely dry in the Waikato and record sunshine in the south

• Temperature:Warm, especially in the west, and inland South Island areas
• Rainfall:Below normal in many North Island areas, and the south of the South Island, above normal in Northland
• Soil moisture: Severe in many North Island areas and the east of the South Island in January, persisting in the North Island during February
• Sunshine: Record low values in Northland; record high values in the south

The summer produced some new records. It was a warm summer, with mean summer temperatures were well above average. The national average temperature of 17.3°C was 0.8°C above normal and the highest for summer since 1998/99. January was particularly warm. Summer temperatures were over 1°C above average in Nelson and inland areas of the South Island. Rainfall was below normal over much of the North Island, and in Southland and Otago, with less than 50 percent (half) of normal in the Waikato. By mid summer severe soil moisture deficits had developed in many North Island areas, and the east of the South Island, which persisted in the North Island in February. Above average summer rainfall occurred in Northland, with 200 percent (double) normal around the Bay of Islands. Record high sunshine hours were observed in the southern South Island, whilst record low sunshine hours occurred in the Far North. The overall summer climate pattern was dominated by the strong La Niña conditions, which produced more anticyclones (‘highs’) south east of the South Island, and more frequent mild north easterly winds over New Zealand.

Major Highlights

• The highest temperature was recorded in January 2008 with 34.8 ºC recorded at both Timaru Airport on the 12^th and Waione on the 22^nd. The lowest air temperature recorded was -1.7 ºC recorded at Hanmer Forest in December on the 8^th.
• From the 30^th December to 22^nd of January, apart from two days, heat wave conditions occurred in inland and eastern areas of the South Island. Wallaceville (Upper Hutt) recorded its highest January temperature on record of 30.9°C (records commenced in 1940) on the 21^st and Palmerston North 31.8°C on the 22^nd (records commenced in 1918).
• Wind speeds of 158 km/hr occurred at Castlepoint and 143 km/hr at Mt Kaukau (Wellington) from the westerly quarter. The former was the highest gust for the month. These were all caused by ex-tropical cyclone Funa on 22 January.
• Persistent rainfall occurred in Northland, with almost 200 mm in the Bay of Islands between 1-10 December. Periods of persistent heavy rainfall occurred on the West Coast of the South Island, with as much as 560 mm at Franz Josef between 9-17 December and 258 mm at Milford Sound between 23-30 December.
• In January, heavy rain localised to the Kapiti District produced widespread flooding in Horowhenua. Over 200 mm of rain fell at Muhunoa, with 320 mm at Oriwa, 140 mm at Waikanae and 120 mm at Levin in 30 hours.
• A subtropical low brought between 200 and 240 mm to the hills between Kaeo and Kaikohe on February 22 and 23^rd, which caused minor flooding in Kaeo.
• Of the five main centres, Auckland was warmest, Christchurch the wettest and sunniest, and Hamilton the driest. Summer temperatures were above average in all five main centres, especially in Hamilton. Rainfall was well above normal in Christchurch, but below normal in the other four, especially in Hamilton. Summer sunshine was well above normal in Dunedin, with the highest total there on record. It was near or below normal in the four other centres.

Temperature

Seasonal mean temperatures were above average throughout much of New Zealand. These were at least 1.0 °C above average in some western North Island areas, Nelson and inland South Island areas. In the east of the North Island and coastal Canterbury these were near average to 0.5°C above average.

Rainfall

Summer rainfall was less than 50 percent (half) of normal in parts of Waikato and less than 75 percent of normal in many other North Island areas, and southern New Zealand. Rainfall was above normal in parts of Northland and Canterbury, with 200 percent (double) normal around the Bay of Islands.

Sunshine

Summer sunshine hours and/or solar radiation were above normal in parts of Northland and Westland, and below normal in South Taranaki, and North Canterbury. Sunshine hours were near normal elsewhere.

Full report

For further information, please contact:

Dr Jim Salinger – Principal Scientist, Climate NIWA National Climate Centre –Auckland Phone +64 9 375 2053j.salinger@...

Geoff Baird –Communications Manager Phone +64 4 386 0543g.baird@...

Acknowledgement of NIWA as the source is required.

 

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NOTABLE WEATHER IN NZ - SUMMER 2007-08

By Ben Tichborne with help from Bob McDavitt

 

The summer of 2007-08 was notable for prolonged warm, dry conditions over large parts of the country, resulting in drought conditions in many places. However, as the summer progressed, there were several spells of wet, unsettled weather which relieved the dryness in some areas. But by the end of the season, a number of regions were still suffering from drought.

 

DECEMBER 2007

 

* 5th - Heavy rain (with some embedded thunderstorms) in Northland.

 

* 6th - Warm 27C maximum in Reefton. Heavy rain in northern and central North Island, e.g. 54mm at Pongakawa (Bay of Plenty), 46mm at Pukeorapa. (Hawke’s Bay) Tornado-like gusts reported near Picton.

 

* 7th - Another 27C maximum in Reefton. A few thunderstorms in Northland.

 

* 8th - 32C maximum in Alexandra. Some heavy rain in northern Hawke’s Bay, eg 50mm in 10 hours at Mahia.

 

* 9th - Very warm in inland North Canterbury, eg 32C maximum in Hanmer, and 31C in Culverden. Some heavy afternoon thunder showers in southwest of North Island, following 26-27C maximums.

 

* 10th-13th - Prolonged heavy rain in Fiordland and Westland. Four day totals include 702mm at Cropp and 766mm at Waiho. Rivers there high, but no significant reports of flooding.

 

* 11th - 32C maximum in Christchurch (33C at Airport), especially unusual due to accompanying high level of humidity. (hot days in Christchurch normally have low humidity levels) 30C maximums in many other places in Canterbury. Heat also helps trigger a thunderstorm near Timaru late afternoon.

 

* 15th - 31C maximum in Culverden; 30C in Hanmer.

 

* 16th/17th - Heavy rain in Westland and Fiordland. (48 hour total of 443mm at Cropp; 62mm at Arthurs Pass on 17th)

 

* 17th - 32C maximum in Kaikoura; 31C at Christchurch Airport before cool southerly change late afternoon. 

* 19th - Heavy rain about central NZ, central North Island, and eastern North Island ranges. (102mm at North Egmont) Only 12C maximum in Culverden and 13C in Masterton.

 

* 23rd/24th - Heavy rain in Fiordland and Westland, eg 110mm at Collier on 22nd.

 

* 25th - Trough and fronts move onto South Island, with some thunderstorms in the south of the South Island as colder air arrives.

 

* 26th - Cold south to southwest flow spreads over NZ, with fresh snow on the mountains, eg Mt Ruapehu. Temperature drops to 7C in Waiouru at 1pm and 8C at Takapau Plains at 4pm. Thunder and hail in parts of northern and central NZ, including Taupo and Mahia. (where hail coats the ground for a while)

 

* 27th - Heavy rain in Fiordland and Westland, eg 163mm at Cropp.

 

* 28th - Only 14C maximums in Masterton and Kaikoura in a cool onshore flow.

 

* 30th - 30C maximum in Ashburton.

 

JANUARY 2008

 

* 1st - Hot 33C maximum in Alexandra. Some heavy rain in Fiordland, eg 99mm in 15 hours at Milford Sound

 

* 2nd - 33C maximum in Ashburton.

 

* 5th - 32C maximum in Alexandra.

 

* 7th-9th - Heavy rain, especially in southwest of North Island. (see details below)

 

* 10th - Very warm in Bay of Plenty and Waikato with 30C maximum in Kawerau and 27C+ maximums elsewhere. However, a cooler southerly flow affects areas further south.

 

* 11th - A chilly 1C minimum in Waiouru in wake of cool southerlies. By contrast, a 33C maximum in Alexandra.

 

* 12th - Northwesterly flow over South Island results in a hot day in Canterbury with 33-36C maximums.

 

* 13th - 31C maximum in Blenheim.

 

* 14th - 31C maximum in Timaru. Heavy rain in Fiordland and Westland. (118mm at Cropp)

 

* 16th - Very warm over most of North Island, with 25C+ maximums in many places. 31C maximums in Tokoroa and Hamilton, and 30C in Kaitaia. 31C maximum also in Alexandra.

 

* 17th - A period of heavy rain in Fiordland, eg 107mm at east Homer.

 

* 18th - Very warm in northern parts of North Island. 33C maximum in Kawerau; 31C in Hamilton; 26-29C maximums in many other places.

 

* 19th - 31C maximum in Alexandra.

 

* 20th-22nd - Ex cyclone Funa. (see details below)

 

* 23rd - Some afternoon thunderstorms around Oamaru.

 

* 24th - 29C maximums in Hamilton and Wanganui.

 

* 25th - 29C maximums in Tokoroa and again in Hamilton.

 

* 30th - Very warm day in north of North Island, eg 31C maximums in Thames and Paeroa; 30C in Hamilton, Tokoroa and Kaitaia.

 

* 31st - 32C maximum in Culverden in a northerly flow.

 

FEBRUARY 2008

 

* 1st - Very warm 33C maximum in Christchurch.

 

* 4th  - 31C maximums in Thames, Paeroa and Hamilton; 30C in Tokoroa.

 

* 6th - Chilly -1C minimum at Hanmer under clear skies and light winds in wake of a cool southeasterly flow.

 

* 7th-8th - Ex Tropical Cyclone Gene passes well offshore to the east - too far away to have any direct impact on NZ weather, but delivering heavy swells to the east coast of the North Island.

 

* 10th-16th - Unsettled period over NZ (see details below)

 

* 20th - Early morning fog in some inland areas of South Island, clearing to give a fine, warm day. 30C maximums in Alexandra and Hanmer.

 

* 21st - Morning fog in some South Island valleys and basins, including Dunedin Airport. Fog clearing to result in another warm, sunny day. (30C maximum again in Alexandra; also in Blenheim and Masterton)

 

* 22nd-24th - Heavy rain and gales in northern areas. (see details below)

 

* 25th - Warm 31C maximum in Hastings.

 

* 28th - Sea-breeze convergence in Whakatane results in a heavy afternoon shower, with 11mm falling in one hour.

 

MAJOR EVENTS

 

* 7th-9th January - Heavy rain, especially in southwest of North Island.

 

Following a week of settled, summery weather during the New Year holiday period, a complex trough slowly crossed NZ during this period. Heavy rain first fell on the South Island West Coast on the 7th. By the 8th, the rain had spread to Central NZ. It was heaviest about the Tararuas and adjacent areas to the west, with totals of 140mm in Waikanae, 120mm in Levin and 320mm at Oriwa (Wellington area). The heavy rain resulted in major flooding in the Kapiti and Horowhenua. Roads were closed, and some homes and the Waikanae camping ground were evacuated.

 

Meanwhile, a shallow low had formed west of the Northland by later that day. Combined with the trough coming from the south, it resulted in rain spreading to remaining northern and western parts of the North Island. Heavy falls were recorded in Northland, but totals elsewhere were much lower and didn't help areas increasingly drying out due to the previous warm, dry weather.

 

Conditions eased on the 9th, as the rain producing system moved away, replaced by a light south to southwest flow over the North Island.

 

Mean sea-level analyses for midday NZDT 7th January to midday NZDT 9th January in 12 hour steps are shown here.

(copyright from http://www.bom.gov.au/nmoc/MSL/index.shtml)

 

* 20th-22nd January - Ex cyclone Funa.

 

The cyclone began to affect the far north on the 20th, as an easterly flow increased over the North Island. Rain became heavy in Northland along with gales in exposed places. Foehn east to northeast winds saw Wanganui reaching a very warm 30C, while a continuing warm spell in inland areas of the South Island resulted in a 32C maximum in Alexandra.

 

On the 21st, Funa moved southwest into the North Tasman Sea, resulting in a north to northeast flow spreading over NZ. Heavy rain and gales continued to lash the far north, and rain spread to other areas exposed to the north. Maximum temperatures were very warm in the lower North Island (30-31C) and inland South Island. (34C in Alexandra and 32C in Manapouri)

 

During the 22nd, the low moved onto the South Island and combined with a cold front moving onto the island. The focus moved onto central NZ, with heavy rain in some exposed areas and gale northerlies, while heavy rain also lashed areas about and west of the Southern Alps. Totals for these few days included 150mm at the Pinnacles (Coromandel), 160mm at Haparapara (Bay of Plenty), 160mm at Little Devil (northwest Nelson), and 227mm at Waiho. Wind gusts reached 41 knots in New Plymouth, 52 knots in Napier, 46 knots in Palmerston North, and 77 knots at Mt Kaukau.

 

Despite the storminess, it continued very warm in the south of the North Island, with 33C maximums in Hastings and Masterton, and 32C maximum in Palmerston North. These areas didn't receive much rain with the storm, and the gales (combined with the high temperatures) felled power-lines and trees, as well as fuelling scrub fires in several parts of the lower North Island.

 

As the low moved to the southeast by the evening of the 22nd, a cooler southerly flow replaced the warm northerly, and conditions eased.

 

Mean sea-level analyses for midday NZDT 20th January to midday NZDT 22nd January in 12 hour steps are shown here.

 

* 10th-16th February - Unsettled period over NZ

 

A few weeks of settled weather came to an end when troughs and lows brought unsettled and stormy weather to several parts of the country, relieving drought conditions in some areas, but also causing some disruption.

 

On the 10th, a low (which had formed in the central Tasman a few days earlier) moved southeast to lie west of Fiordland and to the southeast of the South Island on the 11th. A trough crossed NZ during this period, with thunderstorms in many areas, including early morning storms which caused flash flooding in the Hutt Valley. (23mm in one hour in Lower Hutt and on the 11th) There was also a report of a small tornado at Upper Moutere near Nelson. A cooler southerly change spread onto the South Island during the day, with late afternoon thunder and hailstorms about Canterbury foothills resulting in flash flooding which closed SH73 near Castle Hill for a while (hail blanketed the hill-sides, and a bridge is damaged) 64mm was recorded in Amberley, and 77mm in Rangiora.

 

On the 12th, a new shallow low develop over and to the east of the North Island, with a moist southerly on its western side. Further thunderstorms affected many parts of the North Island, while more rain fell in Mid and North Canterbury and the Kaikoura Coast; the precipitation being welcome after the lengthy dry spell..

 

The low had moved away to the east on the 13th, with a weak ridge giving a reprieve to most areas. However, another trough approached the south later in the day, with rain redeveloping in the southwest of the South Island. The trough crossed the island the next day, preceded by moist northwesterlies and heavy rain in Westland and Fiordland, and followed by colder southerlies.

 

These southerlies brought heavy rain to South and Mid Canterbury later on the 14th, (with some thunderstorms) and to the rest of Canterbury by the 15th, as a low had deepened to the east. Some 30-70mm fell in the area, with some surface flooding, but also more welcome moisture to the soils. Temperatures were unseasonable cold on the 15th, with a chilly 12C maximum in Darfield and 14C maximums in Ashburton and Christchurch. (it was only 9C in Christchurch at noon) Fresh snow fell on the mountains, including the Craigeburn Range, and flakes were reported as low as 900 metres in the Mackenzie Country.

 

The rain in Canterbury eased during the 15th, but the next day the low looped back, with disturbances bringing yet more heavy rain to the area, as well as eastern Otago, this time accompanied by south to southeast gales in exposed areas. A cruise ship was unable to leave Port Chalmers due to the stormy conditions, while a tramper was drowned while crossing a flooded river in the Silverpeaks Range near Dunedin. Wind gusts of 50 knots were recorded at Le Bons Bay and Dunedin, and Taiaroa Heads had gusts up to 61 knots.

 

The low finally moved away by the end of the 16th, and by the next day a decreasing southwesterly flow covered NZ.

 

Mean sea-level analyses for midday NZDT 10th February to midday NZDT 17th February in 12 hour steps are shown here.

 

* 22nd-24th February - Heavy rain and gales in northern areas.

 

This storm mainly affected the north of the North Island, where disruption was caused by heavy rain and gale-force northeasterly winds.

 

A deep subtropical low moved into the North Tasman Sea on the 20th and 21st, and by the 22nd was close enough to give a moist northeasterly flow over NZ. In the north of the North Island, the flow became very strong, with severe gale winds from Auckland northwards. An occluded front accompanying the low also moved onto the far north and moved onto the rest of the country the next day.

 

The heavy rain caused flooding in parts of Northland (200-240mm in hill country between Kaeo and Kaikohe), along with the gales causing additional damage. Auckland was also lashed by the gales on the 23rd, with power outages on the North Shore, and the Symphony Under the Stars concert was postponed. The high gusts recorded included 145kph at Cape Reinga and 110kph on Tiritiri Island. (Hauraki Gulf) The Coromandel Peninsula received heavy rain as well.

 

On the 24th, the Tasman low had broken up, with one part having moved southward into the Southern Ocean, while the other part went well to the northeast of the North Island by the end of the day. Rain eased in northern areas, while winds became light.

 

Mean sea-level analyses for midday NZDT 21st February to midday NZDT 24th February in 12 hour steps are shown here.

 

 

MONTHLY NOTES FOR SUMMER 2007-08 IN CHRISTCHURCH

By Ben Tichborne

 

DECEMBER 2007

This was a much more summer-like month than December 2006, with north or northeasterly flows predominant over NZ. Troughs brought some rain and drizzle to the city at times, but alternated with dry, sunny periods as well. Daytime temperatures were often cooled by the prevailing northeasterlies, but there were a few very warm days as well. The 11th was one of the hottest December days ever recorded in Christchurch - the unusual thing about this day was that it was unusually humid as well, giving the city a tropical feel.. This was due to the airflow being moist north to northeasterly, rather than the dry northwesterly which usually brings the very warm days. By contrast, cold wet southerlies on Boxing Day brought fresh snow to the Alps.

 

JANUARY 2008

Anticyclones were a predominant feature of this month, with little rain falling in the city. There were some warm days in Christchurch but it was often much warmer inland, away from the frequent coastal northeasterly breezes. Daytime maximums reached the mid 30s in many places (both coastal and inland) on the 12th.

 

FEBRUARY 2008

The week from the 10th-16th provided all the noteworthy weather for Christchurch this February, making it one of the city's wettest Februaries on record, and relieving the dry conditions that had been affecting the region for some time. The rest of the month was relatively uneventful - just some brief rain falls of rain as troughs and fronts crossed over, and northeasterly winds predominating.

On the 10/11th, a complex trough crossed the South Island. Some rain fell at times in Christchurch, but heavy downpours with thunder and hail lashed the North Canterbury foothills and adjacent areas (eg Amberley and Rangiora) on the 11th, as a cooler southerly flow developed. By the 12th, a low had formed east of NZ, with decent rain falling in the city and elsewhere in Mid and North Canterbury. There was a temporary break in the weather on the 13th/14th, but an active trough moved onto the South Island on the 14th, with heavy rain later developing in Mid and South Canterbury.

By the 15th, a deep low had formed to the southeast, resulting in a southerly flow and heavy rain throughout much of Canterbury, along with cold temperatures (only 9C in Christchurch at noon) and fresh snow on the mountains. The rain eased during the day, but by early the following day the low had looped around to return yet more heavy rain to the region, now accompanied by southerly gales in exposed coastal places. (especially Banks Peninsula) However, this low finally moved away to the southeast later in the day, clearing the weather by evening.

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