76 Weather and Climate (1988) 8: 76-82

NEW ZEALAND WEATHER

BRIEF REVIEW OF THE WEATHER 0.5 to 1' C above normal over much of the North Island in reigions south of Auckland, and also in SUMMER 1987/88 (Fig. 1) South Canterbury. In most other regions they Rainfall for summer was well above normal in were near normal. Nelson, and North and Central Otago. Totals Cloudier than normal conditions were record- were also above normal in Western Bay of Plenty, ed in most western regions of the South Island East Cape, Gisborne, Manawatu, South West- and in Southland, where sunshine was less than land, Fiordland and in regions south of Canter- 90 percent of normal Sunnier conditions pre- bury. It was drier than usual in Hawkes Bay, vailed in eastern Bay of Plenty, where totals were Marlborough and Canterbury. about 110 percent of normal. The mean temperature for New Zealand, Conditions were generally windier than usual calculated from 7 indicator stations was 16.8' C in areas from Auckland north and in Southland (0.24" C above normal). mean temperatures were and Otago.

.0

150 +1.0

120 +0.5

80 —0.5

50 —1.0

TEMPERATURE RAINFALL Departure from Mormel (1951-80) Percentage of Mormel (1951-00) SUMMER 1987/88 SUMMER 1987/88 Nevi Zealand Meteorological Service Mew Zeeland Meteorological Service

Fig. 1: Summer 1987/88. Rainfall (a) maps based on observations from 46 stations; temperature (b) departure maps based on observations from 44 stations; sunshine (c) based on observations from 35 stations. New Zealand Weather 77

Otago. Totals of only 65 percent of normal at Dunedin Airport and 69 percent of normal at Invercargill Airport were the lowest for Decem- ber since records began at these stations in 1962 1 and 1935 respectively. Thirty houses were reported to have been 1 0 damaged and three people were injured when 90 strong winds occurred in the Auckland suburb of Howick on the afternoon of the 25th. 80 - Rainfall in January was substantially below ( normal over much of the North Island and in northern regions of the South Island (20 to 40% of normal in many places). Little or no rain was recorded in Northland, Auckland and Bay of Plenty after the 2nd, and in Manawatu and Hawkes Bay from the 10th. Some extremely low totals recorded were; 0.6 mm at Matahina (south of Te Teko), 1 3 mm at Kawerau, and 2 1 mm at Bunnythorpe. Rainfall totals of 5 mm or less were recorded in many other places in the north-west of Northland, Eastern Bay of Plenty and Man- SUNSHINE awatu. Percentage or Normal (1051-00) SUMMER 1987/88 New Zealand Meteorologic. Service Rainfall was 140 to 170 percent of normal in ,Y6 East Cape and in regions of the South Island to the south of Canterbury (including the West Coast). Almost twice normal rainfall was record- ed at both Alexandra and Oamaru. A total of 117 MONTHLY SUMMARIES mm (167% of normal) was recorded at Dunedin DECEMBER 1987-FEBRUARY 1988 Airport, and was the highest since 135 mm in 1966. Mean temperatures were about 0.5° C above Due to predominant westerly conditions, rain- normal in Bay of Plenty, Taupo, Rotorua, Wel- fall totals in December were above normal in lington, Wairarapa and Nelson. They werer 1°C Northland, Auckland, and western regions of above in eastern regions of the South Island, both Islands. Almost twice normal rainfall was including Southland. It was cooler in Westland recorded in some areas of Northland and Buller. and Fiordland, where temperatures were almost It was also wetter than normal throughout Bay of 1 C below normal. Maximum temperatures Plenty. In most other regions drier conditions reached 30 to 35° C in many east coast places of prevailed, especially in Hawkes Bay, where totals both islands on the afternoons of the 13th and were only 30 to 60 percent of normal. 14th, in fine north-west conditions. A maximum Mean temperatures were 0.5 to 1' C above of 34.9° C was recorded at Gisborne Airport on normal over much of the North Island and in the 14th. Marlborough, Canterbury and North Otago. In January was a sunny month, especially in Bay Westland, Fiordland and Central Otago they of Plenty, Taranaki, Horowhenua, Nelson and were 0.5 to 1' C below. They were nearly 2' C eastern regions of the South Island, where totals below normal at Alexandra. Elsewhere they were ranged from 120 to 135 percent of normal. only a little below normal. Record high totals, for January were recorded Sunnier than normal conditions predominated atNelson Airport (331 hours), Whakatane Air- in east coast regions of the North Island. In all port (310 hours), New Plymouth Airport (303 other regions (except Northland) rather cloudy hours) and Paraparaumu Airport (302 hours). conditions prevailed. Hours of bright sunshine The records for Nelson Airport began in 1930. were significantly below normal in Westland, This January's total was only 4 hours less than the Fiordland and coastal areas of Southland and highest ever recorded in any month throughout 78 New Zealand Weather

New Zealand. The highest was 335 hours, re- ing a persistent north-east airstream onto New corded at Taupo Airport and Blenheim in Zealand. Thunderstorms were frequent in west- January 1950 and January 1957 respectively. ern regions of the North Island from Taranaki southward in the warm unstable conditions South-west winds, associated with the passage associated with it. During this time there were of a depression, freshened at Christchurch Air- port from about 2.30pm on the 19th, and by seven consecutive days at Kairanga' when tem- 5.30pm had mean speeds of 44 knots, with gusts peratures of at least 27' C were recorded, and six consecutive days at Levin when maximum tem- up to 61 knots (113km/h). A yacht lost its peratures reached 28' C. A maximum of 29' C mooring in the high winds, and was blown onto was recorded at Kelburn (Wellington) on the rocks in Lyttleton Harbour. Some roofs were 12th. It was only the 7th occasion when tem- damaged, as well as trees and fences. At least sixty isolated electric power cuts were attended to peratures of at least 29' C have been recorded throughout the Christchurch area, as trees were there in the last 100 years. A maximum of 28°C was recorded at Hokitika Airport on the 1 lth. blown onto power lines. Later the strong winds This was the highest there for any month since reached Kaikoura, where mean speeds averaged 60 to 62 knots for a short time, with gusts up to 81 records began in 1964. Temperatures of 30 to knots (150km/h). 31' C were recorded on 5 days at Alexandra from the 7th to the 1 lth. Mean temperatures ranged The frequency of strong winds however, was from 0.5 to l' C above normal in most places, but below average over much of New Zealand, due they were 2' C above in Taranaki. They were mainly to the predominance of anticyclonic con- 0.5° C above normal in Canterbury, and 0.5° C ditions. It was windier than normal over South- below normal in Otago. The mean daily min- land, where northwesterlies occurred with their imum of 15.8° C at New Plymouth Airport was second equal highest frequency in January since the highest there in February since records began records began in 1956 (equal to 1983 and 1987). in 1944. February was cloudier and wetter than normal February was cloudier than usual throughout in many regions. New Zealand. In some places hours of bright Rainfall was above normal over much of New sunshine were over 100 hours lower. The cloud- Zealand, especially in Bay of Plenty and Gis- iest regions were Taranaki, Manawatu, the Kai- borne, the central North Island high country, koura Coast and Nelson, where hours ranged Wairarapa, much of Manawatu, coastal Otago from 65 to 75 percent of normal. In many places and Southland. In these regions totals ranged record, or near record low hours of sunshine were from about 200 to 260 percent of normal. A recorded. For example, only 135 hours was substantial portion of the month's rainfall in recorded at Palmerston North D SIR, which was Auckland and Bay of Plenty was recorded on the the lowest since records began in 1953. Only 148 13th and 14th, being associated with a very warm hours were recorded at Nelson Airport, which was the second lowest since records began in moist northerly airstream which affected the 1930. regions. A total of 148 mm was recorded at Whenuapai in the 24 hours to 9am on the 15th; 177 mm at Te Puke in the 48 hours to 9am on the AUTUMN 1988 (Fig. 2) 15th; and 168 mm and 156 mm in the same period Rainfall in Autumn was below normal over at Rotorua Airport and Whakatane Airport res- much of the country, especially, in eastern pectively. Record high totals were recorded at regions of the South Island (except for Southr Rotorua Airport (303 mm) and Palmerston North land), where totals ranged from only 40 to 60 Airport (165 mm). Records began at these places percent of normal. This was due to an above in 1964 and 1944 respectively. A total of 153 mm average frequency of southwesterly airstreams, was recorded at Waingawa, which was the highest and also persistent anticyclonic conditions which since records began in 1926. The total of 156 mm affected the South Island in April. Only 82 mm recorded at Invercargill Airport was the highest was recorded for the season at Christchurch since 1940. Airport, which was the lowest since records Rather warm conditions predominated in began in 1944. More frequent easterly conditions many western regions of the North Island for the over northern regions of the North Island helped week from the 9th to the 1 oth, when a slow to contribute to above normal rainfall in North- moving depression lay in the Tasman Sea, bring- land, Auckland, East Cape and Gisborne. New Zealand Weather 79

°C

150 1.0

120 +0.5

80 —0.5

50 0

RAINFALL TEMPERATURE Percentage of Normal (1951-80) Departure from Normal (1951-80) AUTUMN 1988 AUTUMN 1988 New Zealand Meteorologic. Service New Zealand Meteorological Service

The mean temperature for New Zealand cal- culated from the 7 indicator stations was 12.3' C (1.0° C below normal). Mean temperatures over

120 much of the North Island were near normal, but they were 0.5 to I ° C below normal in Wairarapa, 110 Manawatu, Horowhenua and Wellington. They

90 were below normal over the South Island, especially in Fiordland, Inland Southland and 80 Central Otago, where they were as much as 2' C below normal. This was associated with a high frequency of southwesterlies, which prevailed 54 percent of the time over the south of the South Island (the highest frequency since records began in 1956). The mean daily temperature recorded at Dunedin Airport was 8.6' C (1.9' C) below normal) and 9.2' C at Milford Sound (1.9' C below normal) were the lowest since records began in 1963 and 1935 respectively. Hours of bright sunshine were below normal in Northland and Auckland and above normal in SUNSHINE Percentage I Normal (1051-80) Wairarapa and over much of the South Island. It AUTUMN 1988 N elf Zeeland Meteorological Service was particularly sunny in Canterbury and Otago, where hours were 120 to 135 percent of normal. Hours of bright sunshine were 127 percent of normal at The Hermitage, which was the most Kg. 2: Autumn 1988. Rainfall (a) departure maps based on since 1943 and 134 percent of normal at Queens- observations from 46 stations; temperature (b) departure maps based on observations from 44 stations; sunshine (c) based on town, which was the most since records began in observations from 27 stations. 1930. 80 New Zealand Weather

MONTHLY SUMMARIES ively. In some places rainfall for the 7th and/or MARCH-MAY 1988 8th had a return period exceeding 50 years. Rainfall was only 60 to 70 percent of normal in March was cooler than normal. Manawatu, and as low as 20 percent of normal in A major event in March was that of Tropical some areas of eastern regions of the South Island. cyclone 'Bola'. This was first noted as a tropical Only 13 mm (23% of normal) was recorded at cyclone, on satellite photographs, just to the Timaru Airport. north-east of New Caledonia on the 2nd. By the Mean daily temperatures were just above 5th it was situated about 800 km to the west of the normal in inland areas of Canterbury, but 0.5 to Kermadecs' and was travelling south southwest- 1°C below normal throughout much of the wards toward New Zealand, bringing with it gale remainder of New Zealand. It was much cooler in force east to south-east winds and heavy rain to Westland, Fiordland and Central Otago, where northern and eastern regions of the North Island. mean temperatures were 1.5 to 2' C below Some of the maximum wind gusts recorded normal. A maximum of 27.4' C was recorded at were; 91 knots (167km/h) at Mt Te Aroha on the Hokitika Airport on the 10th, which was the highest there in March since records began in evening of the 6th, 82 knots at Chateau Ruapehu 1964. on the 7th and 70 knots (130 km/h) at Auckland Airport on the 8th. The centre of the storm Hours of bright sunshine were about 110 moved over Northland on the 9th, after which the percent of normal in eastern Bay of Plenty and high winds and rain began to ease. Westland, and up to 120 percent of normal in Prolonged heavy rain in the East Cape and Canterbury and Otago. It was cloudier in North- Gisborne regions resulted in severe flooding land and in other North Island regions south of throughout many rural areas. A state of em- Hawkes Bay, where hours ranged from 80 to 90 ergency was declared and approximately 3000 percent of normal. people had to be evacuated. Three people lost their lives in a car which had stalled in flood April was cooler and much drier than normal. waters. A strong north-west airstream spread onto the High winds affected the North Taranaki region South Island, with gales about Wellington on the causing damage to nearly 500 houses. 9th. Wind gusts up to 71 knots (132 km/h) were Over 11,000 claims for damages were lodged recorded at Kelburn, and 74 knots (137 km/h) at with insurance companies after the storm. Dam- Wellington Airport. age due to the floods and high winds was Anticyclonic conditions were very persistent in estimated to have been in excess of $73 million April; most crossed over the South Island and Rainfall for the month was more than twice some were very intense. On the 29th, mean sea normal in Northland, Auckland, much of Coro- level pressures as high as 1040.5, 1040.4 and mandel, East Cape, Gisborne, Northern Hawkes 1040.2 hPa were recorded at Invercargill, Dun- Bay and in inland places of the Nelson region. A edin and Christchurch Airports respectively. total of 792 mm (671% of normal) was recorded at These were all higher than the previous record for Tutira (Hawkes Bay). This was the greatest New Zealand in April (since 1960), of 1038.0 hPa, amount recorded there in any month since recorded at Lake Coleridge on the same date in records began in 1895, and the most since a April 1985. similar amount (781 mm) was recorded in April As a result of persistent high pressures, north- 1938. A total of 776 mm (426% of normal) was easterly winds prevailed (for 43% of the time) recorded at Te Pua Spring (East Cape). Very over the north of the North Island, and there was large amounts of rain, associated with Tropical generally less wind than usual over the whole of Cyclone Bola, were recorded in these regions New Zealand. Average mean sea level pressures from the 6th to the 8th. Some extremely high were up to 10 hPa above normal over the south of totals were; 419 mm and 368 mm in the 24 hours the South Island. The average mean sea level to 9am on the 8th at Te Pua Springs and pressure at Invercargill at 9am was 1022.8 hPa, Ruangarehu (East Cape) respectively, 320 mm the highest since records began in 1949. The and 329 mm at Tutira Station in the 24 hours to average at Kelburn was 1024.1 hPa, the 3rd 9am on the 8th and to 9am on the 9th respect- highest in April since records began in 1864. This New Zealand Weather 81 was only 0.6 hPa lower than the record of 1024.7 of normal, being the highest in April in 16 years of hPa in 1875. record. Total rainfall for the month was well below In May it was warmer than normal over much normal over almost the whole of New Zealand. In of the North Island, but colder over the South many western regions of the North Island, in- Island. cluding Northland, and in regions of the South Surface flooding occurred in Invercargill on Island north of Otago, rainfall ranged from only the 14th and 15th. This was reported to be the 15 to 40 percent of normal. Only 1 mm was worst in ten years, excepting that of 1984. A civil recorded at Brancott Valley (near Blenheim), 6 emergency was declared in Greymouth due to mm (9 percent of normal) at Grovetown (also flooding on the 19th. At least a metre of water was near Blenheim), 6 mm at Molesworth (9 percent reported to have been flowing through most of of normal), and 7 mm at Blenheim Research the central business area. Damage costs were station. Other low rainfall totals were 10 mm at estimated to be around $2 million, with 102 Kaitaia Observatory and Timaru Airport. A total families affected. of 32 mm (14 percent of normal) was recorded at On the 19th gale force northwesterlies caused Greymouth, which was the lowest since 1948, damage to approximately 60 houses in Welling- and a total of 64 mm (15 percent of the normal of ton. One house lost its roof and a car was blown 413 mm) was recorded at Otira, which was the off the Rimutaka Road. Maximum gusts record- lowest in 83 years of record. In many places little, ed at Kelburn and Wellington Airport were 72 or no rain was recorded during the last two weeks and 75 knots respectively. of April. Totals ranged from 105 to 130 percent of normal in the Gisborne and East Cape regions. A very cold southerly airstream followed the passage of a cold front over the South Island on Mean daily temperatures were below normal the 23rd. This was accompanied by snowfall to throughout New Zealand, ranging from 0.5° C low levels in southern and eastern regions of the below in Northland and Bay of Plenty, to .5 to South Island, as far north as Canterbury. Up to 2' C below in Horowhenua, East coast regions of 2.5cm of snow lay on the runway at Invercargill the North Island from Hawkes Bay south and Airport during the morning of the 23rd. As much over much of the South Island. as 25cm of snow was recorded in the Tumrau area In most places mean daily maximum tem- of Southland, and in some places in central Otago peratures were a little below normal, but mean up to 45cm of snow was reported. A maximum of daily minimum temperatures were generally only 3.1' C was recorded at Invercargill on the much lower than normal. Some very large de- 23rd. This was the lowest daily maximum re- partures were 3.2° C below normal at Para- corded at Invercargill in May in over 40 years. parumu Airport, and 2.8° C below normal at In May, persistent southwesterly conditions Queenstown Airport. These were the lowest on helped contribute to a record frequency of strong record for these stations since 1953 and 1969 winds, over the south of the South Island. At respectively. The mean daily minimum at Dun- Invercargill, the winds were southwesterly edin Airport was 2.3° C below normal, the second for 52 percent of the time. lowest since records began in 1963. Similar Rainfall totals ranged from 120 to 180 percent departures were also recorded in much of Marl- of normal in much of Northland and Auckland, borough, Nelson, and inland North Canterbury. inland highcountry areas of Nelson and North Canterbury, and in coastal areas of Southland. It Severe air frost occurred at Dunedin Airport was very wet at Cape Reinga, where the total was on the 30th, when a minimum temperature of over twice normal. Totals were 30 to 70 percent of -6.4° C was recorded, the lowest recorded for normal in Gisborne, Hawkes Bay, the Kaikoura April, since records began in 1963. coast, some parts of North Canterbury and in April was in all regions, except for Gisborne Central Otago. Elsewhere rainfall was near and East Cape, sunnier than usual. It was part- normal for May. icularly sunny in Taranaki, Manawatu, Nelson, Hail was reported at Invercargill Airport on on the West Coast of the South Island, and in each day from the 12th to the 24th in cold Canterbury, where hours ranged from 120 to 130 southwesterly conditions. This was the highest percent of normal. The total of 228 hours re- frequency of occurrence, in May, since records corded at New Plymouth Airport was 130 percent began in 1949. 82 New Zealand Weather

Temperatures as high as 25' C were recorded land and most places north of Otago, to 2°C in places in the Gisborne and Hawkes Bay below normal in Otago, and as much as 3°C regions, in warm north-west conditions, on the below normal in Fiordland. The mean tem- 9th and 10th. The maximum of 25.0°C recorded perature, at Milford Sound, of 5.7' C (2.8' C at Gisborne Airport on the 9th was the highest below normal), was the lowest recorded there in there in May since records began in 1937. May since records began in 1935. Some severe air and ground frosts were re- Hours of sunshine were below normal in corded in New Zealand, especially in the South western regions of the North Island north of Island, from the 24th to the 28th. Record low Manawatu, and in Southland. It was particularly screen and grass minimum temperatures were cloudy from Taranaki to Auckland, where hours established in many places. Some of these were were only 60 to 70 percent of normal. A total of 84 the lowest in May in over 20 to 30 years. Screen hours (60% of normal) was recorded in Auckland minimums of -8.8° C were recorded at Dunedin City. This was the lowest since 83 hours in 1969. Airport and Queenstown on the 28th. These were It was very sunny in eastern regions of New the lowest since 1962 and 1969 respectively. A Zealand, from Hawkes Bay to Otago, including grass minimum temperature of -12.2' C recorded Wellington. In these regions hours of bright at Dunedin Airport on the 28th was also the sunshine ranged from 120 to 150 percent of coldest there since records began in 1962. Screen normal. Christchurch Airport recorded 177 minimum temperatures of less than -6.0° C were hours (139% of normal), which was the highest recorded every day from the 21st to the 30th at since records began in 1949. A total of 152 hours Alexandra. On five of these days they were lower (146% of normal) was recorded at Dunedin than -9.0° C. The lowest was -9.8"C on the 21st. Airport, which was the most since records began Some unoccupied houses were reported to have in 1963. been flooded due to burst water pipes from the expansion of freezing water during this period. ACKNOWLEDGEMENT Mean daily temperatures were above 1°C above normal in most places in the North Island. Thanks are due to the New Zealand Meteor- In Wellington and Wairarapa, where they were a ological Service for providing the climatological little below normal. Over the South Island they data from which this summary was compiled. ranged from 1° C below normal in coastal South- S. Burgess