Weather and Climate (1991) 11: 31-36 31 NEW ZEALAND WEATHER BRIEF REVIEW OF WINTER AND SPRING 1990 WINTER 1990 (Fig. 1) Winter 1990 was very dry in the far south. Northeasterlies brought sunny conditions to Southland and above average temperatures to the entire country. In most other regions it was cloudy and wet. Coastal Southland, South Otago and Dunedin recorded less than 60 percent of average winter rainfall. Record low rainfall for the season of 132 mm (56 percent of average) was measured at Invercargill Airport where measurements began in 1939. Rainfall totalling 78mm (57 percent of average) was recorded at Dunedin Airport, which was the lowest for the season since 72mm in 1970. Overall for New Zealand, the winter of 1990 was the 7th warmest since records began in 1853. The average daily temperature for the whole country during winter was 8.8 C, which was 0.7 degrees above Temperatures have been much warmer than average for all of the winters since 1984, with the exception of 1986. Mean temperatures were 1.0 degrees above average in Gisborne and along the Kaikoura Coast, and 0.4 to 0.9 degrees above average in most other places. The winter was wetter than usual over the remainder of New Zealand, especially in areas exposed to the north and east. Rainfall ranged from 120 to 150 percent of average in +1.0 RAINFALL +1.0 80 WINTER 1990 Fig 1: Winter 1990. Rainfall map based on observations from 43 stations; temperature departure map based on observations from 36 stations; sunshine based on observations from 16 stations. +1.0 TEMPERATURE departure from normal WINTER 1990
32 SUNNY SUNSHINE WINTER 1990 Auckland, Bay of Plenty, Rotorua, Nelson, and in the east of both Islands as far south as North Otago. Totals were well up in Napier (178 percent of average) and Oamaru (167 percent of average). Southland had sunshine hour totals ranging from 10 to 15 percent above Sunshine was about average in eastern regions of both Islands. In all other regions it was cloudier than usual. The warmer and wetter conditions that prevailed in most areas in winter were caused by frequent troughs of low pressure, and more prevalent northeasterly winds associated with depressions that crossed over the country. MONTHLY HIGHLIGHTS JUNE 1990 - AUGUST 1990 June continued the trend this year of warmer than usual weather. Northerlies brought very dry conditions to eastern regions of the South Island. In contrast, it was rather cloudy and wet in the North Island from Taranaki to Wellington, and on the west coast of the South Island. It was very dry in Dunedin, and rather dry in all eastern regions of the South Island, where rainfall totals ranged from 20 to 50 percent of normal. Only 1 lmm was recorded at Dunedin Airport, which was a one in ten year event. The lowest on record there for June is 8mm. Rainfall was also low in Northland where about 60 percent of normal was recorded. Rainfall was one and a half to two times normal in Fiordland, and up to one and a half times normal in Taranaki. The average daily temperature for the whole country was 8.7 C, which was 0.6 degrees above normal. However, daily maximum temperatures were well below normal in eastern regions of both Islands during cold southerly conditions from the 6th through to the 14th. Average temperatures were about 1.0 C above normal in Wairarapa, Marlborough, South Canterbury and North Otago. In South Island regions and the southern half of the North Island they were between 0.5 and 1.0 C above normal. Elsewhere they were near normal. Near record high temperatures for June were recorded in Auckland on the 2nd, and in Hawke's Bay on the 3rd: 20 C in Auckland, and 21.5 C in Havelock North, both 1 tpc below the highest ever recorded in these locations in June. Hours of bright sunshine were only 70 to 80 percent of normal from Wanganui to Wellington, and 85 percent of normal in Westland. in contrast, it was very sunny in Gisborne, which had almost 25 percent more than the normal for June. July was also warmer than usual. It was rather dry in the south of the North Island and in eastern areas of Canterbury, Otago and Southland. Wetter weather continued on the West Coast of the South Island. Heavy rainfall occurred in Hawke's Bay during the last two days of the month. Record low rainfall for July was recorded at: Centre Year records began Rainfall Percentage total, mm of normal Wellington 35 24 1862 Paraprarumu Airport 39 34 1945 Rainfall totals ranged from 35 to 65 percent of normal in eastern areas of Canterbury, Otago and Southland. Heavy rainfall fell in
33 Hawke's Bay, during moist easterly conditions, on the 30th and 31st. More than 100mm were recorded at Havelock North during the period. As a result totals in the region were almost twice the July normal. Auckland experienced t h e third equal warmest July ever recorded and Wellington the fourth equal warmest; mean temperatures at these centres were: Centre Auckland Wellington Mean Departure Y e a r temperature from normal records began +1.2 C 1 8 6 2 12.4'C 9.5 C +1.1 C 1 8 6 2 The average daily temperature f o r the whole country of 8.4 C was 0.8 of a degree above normal. Mean temperatures were 0.8 to 1.2 C above normal in most regions. They were 1.3 to 1.6 C above normal in Auckland and Waikato, and normal to half a degree above normal in South Westland, Fiordland, southern areas of Otago and Southland. Extremely cold temperatures occurred at Dunedin Airport during the early hours of the morning on the 20th and 21st. Grass temperatures at the Airport dropped to -12.9 C on the 20th and -12.3 C on the 21st. Air temperatures fell to -8.3 C on the 21st. These were the lowest temperatures recorded at Dunedin Airport since measurements began in 1967. Unusually high temperatures for July were recorded along the Kaikoura Coast on the 26th. They reached 21.8 C at Kaikoura, which was only 2.1 degrees below the New Zealand record of 23.9 C recorded at Hastings in 1942. Hours of bright sunshine were mostly 10 to 20 percent above normal in Wellington, Wairarapa, Canterbury, Otago and Southland. Cloudier than usual conditions were recorded in Auckland and Bay of Plenty where totals were 80 to 90 percent of normal. August was the eighth month this year with warmer than average conditions. Extremely high rainfall for August was recorded at Rotorua, Motueka, Blenheim, and in much of Canterbury and North otago. It was also very wet in Southern Hawke's Bay. In contrast it was very dry in Southland and Fiordland. High winds attributed to a tornado, caused considerable damage to property in Inglewood (Taranaki) on the 12th. Rainfall totals were two to three times the average for August at Rotorua, Kawerau, in southern Hawke's Bay, Marlborough, and Canterbury. More than three times the average rainfall was recorded at Riwaka (Motueka), and at the Christchurch and Oamaru Airports. Record high rainfalls for August were: Rotorua Kawerau Riwaka, Motueka Christchurch Airport Oamaru Rainfall total, mm 331 463 Percentage Year records of average began 227 1899 260 1954 533 351 1943 171 144 313 369 1943 1941 Prolonged heavy rain caused severe flooding and a state of civil emergency in Motueka on the 10th and 1 lth. Twenty six homes were evacuated. A record high total for two days or 286mm was recorded at Riwaka during the period. Rainfall was below average in Westland, Fiordland, Central Otago and Southland. Totals of lomm (22 percent of average) and 20mm (32 percent of average) were recorded at Queenstown a n d Invercargill Airports respectively. The average temperature for the whole country of 9.2 C was 0.6 of a degree above Mean temperatures in most regions were 0.5 to 1.0 C above They were near average i n areas o f Northland and Otago. A few high temperatures for August were recorded during the month. These were 19.6 'C at Ohakea on the afternoon of the 6th (second highest since records began in 1940), and 20 C at Franz Josef on the 23rd (highest since measurements began in 1953). It was cloudier than usual in many regions. Hours ranged from 55 to 70 percent of average in Westland, and 70 to 80 percent of average in Auckland, Waikato, Bay of Plenty, Wellington, Marlborough and Nelson. Sunnier than usual conditions prevailed in Fiordland, Southland a n d Central Otago, where hours were 10 to 25 percent above SPRING 1990 (Fig. 2) The very dry conditions experienced during winter over the south of the South Island, continued into spring. Rainfall was well above average in Nelson and along the Kaikoura Coast. These conditions were caused by more frequent north to northeasterly airstreams over New Zealand.
34 100 NEAR 100 NEAR SUNNY 110 100 110 SUNSHINE SPRING 1990 120 WET RAINFALL SPRING 1990 Fig 2: Spring 1990. Rainfall map based on observations from 46 stations; temperature departure map based on observations from 40 stations; sunshine based on observations from 17 stations. Only 35 to 60 percent of average spring rainfall was recorded in the Southern lakes area of the South Island. The total of 72mm measured at Queenstown Airport (38 percent of average) was the lowest since records began there in 1968. Conditions were also drier than usual in Fiordland, Southland, Central and South Otago, with total rainfall 60 to 80 percent of Rainfall was 50 percent more than average in Nelson and Kaikoura. It was also wetter than usual in Rotorua, Manawatu, Wellington and South Canterbury. Temperatures were close to average in most places. However, it was warmer than usual by 0.5 to 0.8 C in Auckland, Waikato, Bay of Plenty, Gisborne, Hawke's Bay, South Westland and Fiordland. Cantabrian's caught the sunshine, with totals 12 percent above In all other regions hours were near
MONTHLY HIGHLIGHTS SEPTEMBER - NOVEMBER 1990 September was very dry in eastern areas of Northland, from Horowhenua to Wanganui, and over the southern half of the South Island. More anticyclones than usual over southern regions of New Zealand brought above average sunshine to many areas and below average temperatures to much of the North Island. Little significant rain was recorded in inland areas of South Canterbury and North and Central Otago, where in many places rainfall was less than lomm (15 to 35 percent of average). Only lmm was recorded at Bendigo, being the lowest recorded there for September since 1969. Totals were 20 to 40 percent of average in eastern areas of Northland, and from Wanganui to Horowhenua. However, more than twice average rainfall occurred along the Kaikoura Coast. September was the first month with lower than average temperatures over the North Island since May 1988. The average for the whole country of 9.9 C was OA 'C below average, and the lowest for September since 1977. Hours of bright sunshine were 20 percent above average in Rotorua, Bay of Plenty and Canterbury. I t was also sunnier than usual over the rest of the North Island, and i n Marlborough and Southland. October was warmer than usual, especially in Auckland, Waikato and Gisborne. However, temperatures were below average in Southland and Otago where more rainfall than average was recorded. Westerly airstreams predominated, but winds from between north and east were more frequent than usual over much of the country. Winds from between south and east were more frequent than usual over the south of the South Island. Temperatures were 1.5 C above average in West Auckland, much of Waikato and in Gisborne. Over much of the remainder of the North Island and in Marlborough and Nelson they were 1.0 to 1.4 C above The more frequent winds from between south and east over Southland and Otago kept temperatures there 0. 5 t o 1.0 C below Up to three times the average October rainfall was recorded in inland parts of South Canterbury, and up to twice the average rain- 35 fall was measured in coastal regions of North Otago. A total of 80mm of rain was recorded overnight at Rotorua from 6pm on the 14th, during moist northerly conditions associated with an active front. Drier than usual conditions prevailed in parts o f Northland, Taranaki, Buller and coastal areas of North Canterbury where totals were as low as 50 percent of Hours of bright sunshine were 10 percent above average in Westland, Nelson and North Canterbury. However, cloudier than usual skies prevailed over the far north of the North Island, in Waikato, Bay of Plenty, Rotorua, Taranaki and Southland. November was very much wetter than usual in Marlborough and Nelson. I n contrast, rainfall was well below average in Fiordland, Southland a n d a b o u t t h e MacKenzie Basin/Southern Lakes area. These conditions were due t o depressions passing over the North Island bringing more frequent east to northeasterly winds. Over twice average rainfall occurred in Marlborough and Nelson. Much of Nelson's rain fell during two 48-hour events. More than 100mm was measured over the 1 lth and 12th in moist northerly conditions, and a t least 50mm over the 18th and 19th i n similar weather. Rainfall was twice average in Wellington and Rotorua. The total of 185mm recorded at Rotorua was the fifth highest total for November in 92 years of record. Little significant rain fell in Southland and the MacKenzie Basin/Southern Lakes area. Only 12mm (32 percent of average) was measured at Waipiata (Maniototo). Totals were 40 to 65 percent of average in Fiordland and along the South Otago coast. Temperatures were up to 1.5 C above average in Fiordland, and 1.0 C above average along the remainder of the West Coast, in Auckland, Waikato and Southland. They were 0.5 to 1 'C above average over much of the remainder of New Zealand, and close to average in eastern regions from Wairarapa to Otago, including Wellington. Temperatures reached 27 C at Haast on the 13th, during warm southeasterly fohn wind conditions. This was one of the highest temperatures ever recorded along the West Coast for November where records began in 1866.
36 Hours of bright sunshine were as much as 25 percent below average in Marlborough and Nelson, and 15 percent below average in Wellington and Rotorua. Sunnier weather prevailed in Wairarapa, Buller, and Fiordland, where totals were about 10 percent above Many thanks are due to the New Zealand Meteorological Service for providing the climatological information from which this summary was compiled. Stuart M. Burgess