Weather and Climate (1989) 9: 29-36 29

NEW ZEALAND WEATHER

BRIEF REVIEW OF THE WEATHER percent of normal in much of Canterbury and as low as 50 percent of normal in coastal WINTER 1988 (Fig. 1) areas of North . Rainfall for winter was above normal in The mean temperature for , calculated from 7 indicator stations (one of central highcountry of the North Is- which goes back to 1853) was 9.1°C. This was land, Wanganui, Manawatu, along the west 1.0°C above normal and was the third highest coast of the , in Southland, Otago recorded. The warmest winter was that of and inland highcountry areas of Canterbury. The wettest regions were Manawatu, South 1984 when 9.4°C was recorded. In some places Westland and inland areas of Southland and in central Otago and inland Canterbury mean temperatures were as high as 1.5-2°C above Otago, where rainfall totals ranged between normal. 150 and 190 percent of normal. It was drier than usual in all regions of New One of the major factors which contributed Zealand which were sheltered from the west to the warmer weather was that there were and south-west. Rainfall was less than 60 fewer periods of very cold southerly condi-

.1.0

+0.6

—0,6

—1.0

SUNSHINE Pereentege of Normal (1061-00) Seimrture from Mks, 0051 -00) WINTER WINTER ((IV))TEMPERAXURE Nme Zei•land Meteorological Service Neer Unload Mettorotogmal Service 1

Fig. 1: Winter 1988. Rainfall (a) maps based on observations from 46 stations; temperature (b) departure maps based on observations from 43 stations; sunshine (c) based on observations from 33 stations. 30 New Zealand Weather

Conditions were generally windier than usu- al in the south of the , and over much of the South Island, especially in South- land and Otago where windy days (gusts of at ISO least 34 knots) occurred with almost twice the

120 normal frequency. Strong winds (recorded by radar balloon flights) at midday, over South- 80 land occurred on 44 percent of the days. This

50 was the most since 45 percent in 1949.

MONTHLY SUMMARIES JUNE-AUGUST 1988 June was warmer than usual. Mean daily temperatures were at least 0.5°C above normal throughout much of New Zealand. They were 1.5-2°C higher in places north of , in western , western regions of the North Island from to Manawatu and in inland Canter- RAINFALL of Nom, (1051-00, WINTER 1988 bury. A very low air temperature of -8.4'c was Mow notiond ifetoorolcoficol Service recorded at Airport on the morning of the 16th, together with a -10.3°C ground frost. This was the lowest air temperature recorded there in any month since records began in 1963. Temperatures as high as 22.5°C tions than is usual, and these lasted for only were recorded at Airport in brief periods of time. For example, the aver- age number of days in winter (1931-74) with warm dry northwesterly conditions on the 8th. This was the highest in 33 years of records. A maximum temperatures of less than 8.0°C recorded at Kelburn is 9. This winter there maximum temperature of 24.2°C was record- were only 2. ed at Napier Airport in similar conditions on the 19th, which was the highest measured Only one ground frost was recorded at Kel- since records began in 1954. burn (the normal is 2), which was the least since 1971 when there were none. This made Rainfall was only 30-40 percent of normal the winter the second least frosty at Kelburn in Hawkes Bay and northern parts of the since records began in 1928. Auckland . It was also drier than norm- al in Northland, other parts of Auckland and Cloudier than normal conditions were re- in eastern regions of New Zealand sheltered corded in all western regions of the North from the south-west, where totals ranged Island north of Horowhenua and along the from 40-70 percent of normal. Rainfall was west coast of the South Island. The winter was 120-180 percent of normal in Manawatu, along rather cloudy in Auckland and Waikato. Hours the West Coast of the South Island and in of bright sunshine were only 76 percent of Central Otago. Totals were almost twice normal at , which was the low- normal in South Westland. Only 378 mm (59% est since records began in 1963, and 77 per- of normal) was recorded at Kelburn in the 6 cent of normal at Ruakura which was the months ending 30 June. This was the lowest lowest since records began in 1937. since 287 mm in 1939 and the 9th lowest since Sunnier than normal conditions prevailed in recording began in 1862. Heavy rain, totalling eastern regions of New Zealand from Hawkes 153 mm, was recorded at Glenorchy (near Bay to South Canterbury. Just over 120 per- ) in the 24 hours to 9am on the 8th. cent of normal sunshine was recorded at Five houses were evacuated and hundreds of hectares of farmland were flooded due to , making it the sunniest since 1959. heavy rain in the same area on the 19th. On New Zealand Weather 31 the same day heavy rain caused slips and ter many homes were flooded. About 10 closed the Manawatu Gorge road for a time. houses were seriously damaged by the water Hours of bright sunshine were 110-120 per- and more than 100 were evacuated. The flood cent of normal over much of the South Island. was reported as being the worst affecting the In Canterbury and Southland they were as region since 1976 and damage was estimated high as 125 percent of normal. Over the North at $2-3 million. Island it was cloudier than usual (especially in Drier than normal conditions were recorded Horowhenua and Manawatu with 65-75 per- in eastern regions of the South Island from cent of normal hours). The region from East Kaikoura to North Otago. In these regions Cape to Poverty Bay had near normal totals ranged from 40-60 percent of normal. sunshine. Only 8 mm was recorded at . On the whole, July was wndier than average For the 7 months from 1 January to 31 July, over much of New Zealand, especially in the only 200 mm had been recorded at Christ- far south. church Airport. This was the least ever Strong winds occurred for 37 percent of the recroded for that period since records began time, for the period 1 January to 31 July over in 1944, being only 50 percent of normal. the south of the South Island. This was equal Temperatures were much warmer than to 37 percent in the same period in 1987, and usual over most of New Zealand in July. Mean was the highest since records began in 1956. daily temperatures were 1-1.5°C above norm- Rainfall was above normal in eastern re- al in many regions. They were about 2°C gions of the North Island north of , above in Waikato, Manawatu and eastern re- high country regions, Southland, much of gions of the South Island (north of Southland Otago and in most regions exposed to the west and coastal Otago). In some inland areas of or south-west. It was very wet in Auckland Canterbury and Otago they were as much as City, western Manawatu, Fiordland and 3°C above normal. The mean temperature for Southland, with totals being approximately New Zealand, calculated from 7 indicator sta- twice normal (and up to three times normal in tions, was 8.9°C. This was 1.3°C above normal Central Otago). A total of 154 mm (214% of and was the highest on record (equal with normal) recorded at Airport was 8.9°C in 1985). The mean temperature record- the highest recorded there in July, since ed at Kelburn was 9.7°C (1.3°C above normal), records began in 1939. which was the second equal highest since records began in 1928. Other Heavy rain was recorded in Auckland on the records indicate that, for Kelburn, it was 17th, where in most places totals for the 24 likely to have been the second highest since hours to 9am on the 18th ranged from 60-95 1862. The highest was 9.8°C in July 1985. The mm, with some surface flooding. Flooding also occurred in Gisborne when over 100 mm mean temperature at Christchurch of 7.1°C was recorded in the 48 hours to 9am on the (2.0°C above normal) was the highest since 18th. A total of 304 mm was recorded at records began in 1954. Coromandel in the 72 hours to 9am on the Hours of bright sunshine were below normal 18th; 186 mm having been recorded in the 24 in most western regions of New Zealand. They hours to 9am on the 17th. were very low in Auckland, Bay of Plenty, , and central regions of the North A total of 31 mm was recorded at Kelburn, Island, where they ranged from 65-80 percent Wellington, in moist north-west conditions, in of normal. Only 98 hours (74 % of normal) the hour from just before midnight on the 23rd were recorded at Airport, until just before 1 lam on the 24th. This which was the lowest since records began in equalled the all time record for one hour's rain at Kelburn. 1939). It was sunnier in eastern regions, from Heavy rain was recorded again in North- Hawkes Bay to North Canterbury and in Wel- land, Auckland, Bay of Plenty and Manawatu lington. Hours of bright sunshine were up to on the 24th. Most totals to 9am, on the 25th 130 percent of normal in Wairarapa. ranged from 65-85 mm. A state of civil emer- gency was declared in , af- August was another windier than average 32 New Zealand Weather month over much of New Zealand, especially of normal. It was especially sunny in Christ- in the far south. Strong winds occurred for 50 church where a total of 190 hours (134% of percent of the midday readings over the south normal) was recorded, which was the second of the South Island, which was the highest in equal sunniest August since records began in August since records began in 1956. The high 1949. frequency of strong winds was due to the lack of anticyclonic conditions; persistent west to SPRING 1988 (Fig. 2) south-west airstreams affected the region. Strong winds occurred for 39 percent of the Rainfall for Spring was below normal in midday readings, for the period 1 January to East Cape, Gisborne and Marlborough. Par- 31 August over the south of the South Island. ticularly dry conditions prevailed in eastern This was the highest frequency there since regions of the South Island, as far south as records began in 1956. Otago, where totals were only 35-50 percent of normal. Only 55 mm (41% of normal) was Light snow was recorded in eastern regions recorded for the season at Christchurch Air- of the South Island in cold southerly conditions on the 1 lth. Cold south-west winds following port, which was the lowest since 45 mm (34 % the passage of a cold front over New Zealand of normal) in 1949; records began in 1944. The low rainfall in eastern regions was the resut on the 19th also brought snow to Otago. Anoth- of unusually persistent north-west conditions. er cold southerly airstream moved on to the South Island on the 24th and covered the North-west winds (recorded by radar balloon whole country on the 25th, bringing more hail flights) over the south of the South Island, at and sleet to Wellington and also snow, which midday, occurred on 58 percent of the days. lay for a time in many eastern regions of the This was the most, equal with 1978, since South Island. Similar conditions occurred on records began in 1956. These also contributed the 30th with snow in Southland and Otago, to above normal rainfall in western regions of which later spread northward. A light scatter- ing of snow fell on the Rimutaka Range (east of Wellington), and sleet was reported in the Wellington suburbs of Newlands and Karori in the afternoon. Rainfall totals ranged between 120-180 per- cent of normal in Auckland, Taupo, central high country regions of the North Island, south Westland, Fiordland and Southland. Totals ranged between 40-70 percent of normal in Northland, eastern regions of the North Is- land, Wellington, Marlborough, Nelson and coastal areas of Canterbury and Otago. Over much of New Zealand August was warmer than usual. Mean daily temperatures were 0.5 to 1°C above normal in many regions. They were as high as 1.5°C above normal in some areas of inland Canterbury. Maximum temperatures as high as 22°C were recorded in Hawkes Bay in north-west conditions on the

24th. RAINFALL Poreento.o of Normal (1251-80) SPRING 1908 Hours of bright sunshine ranged from 75-90 Now Zealand lietoorologocol Sof not percent of normal in Northland, Auckland and western regions of the South Island. It was sunnier in all eastern regions of New Fig 2: Spring 1988 Zealand, and Manawatu, Horowhenua, Wel- Rainfall (a) departure maps based on observations lington and Nelson. In these regions hours of from 46 stations; temperature (b) departure maps based on observations from 46 stations (c) based on observations bright sunshine were mostly 110-120 percent from 23 stations. New Zealand Weather 33

The mean temperature for New Zealand calculated from 7 indicator stations was 13.3°C (1.2°C above normal) and was the high- .0 est since 13.2°C recorded in 1893, and also the .1.0 highest since records began in 1853. Mean

.0.5 temperatures were 1-5°C above normal in many regions, but they were 2-2.5°C above —0.5 normal in eastern regions of the North Island

—1.0 and in Marlborough and Canterbury. Mean temperatures in South Westland and Fiord- land were about normal. Hours of bright sunshine were rather low (only 75-85% of normal) due to the unsettled conditions which affected western regions, Northland and Auckland. Elsewhere they were near normal.

MONTHLY SUMMARIES SEPTEMBER-NOVEMBER 1988 TEMPERATURE 8.,rtur. Kormnal SPRING 1988 New Zealand hdeLoorolopeal Sart. September was, in many places, much cloudier and warmer than normal. A major event in September was that of flooding. Heavy rainfall affected Southern Hawkes Bay and Northern Wairarapa on the 1st and 2nd. In many places totals of 150-200

X mm were recorded in the 48 hours to 9am on the 3rd. These conditions were associated with 120 a strong moist easterly airstream which cov- 110 ered the area, as a slow moving depression

90 crossed the North Island to the north of the regions. Flooding was extensive in flat low 80 lying farmland areas in the north of Wairarapa. A substantial amount of rain was also re- corded in , on the 12th and 13th, in moist northwesterly conditions, when a partic- ularly active trough affected the area. Heavy rain, totalling 111 mm at Greymouth and as much as 200 mm in the high country, was recorded in the 24 hours to 9am on the 13th. This caused the Grey River to burst its banks and severe flooding occurred in Greymouth.

SUNSHINE About 200 houses were flooded and the flood Peacoats,. ot00) SPRING INA)) was noted as being the worst ever recorded New Zealand ideteni alogic•I Ne,eina 1 there. A notable feature of the month was the absence of cold southerly airstreams. There New Zealand south of about Auckland. Record were few anticyclonic events and westerly high spring rainfall (as much as twice normal) airstreams were rather persistent. Combined, was recorded in much of South Westland and these conditions contributed to make Septem- Fiordland. ber a much warmer month, with very little 34 New Zealand Weather

rainfall in eastern regions of the South Island below normal sunshine and the seventh month and more wind than usual over much of the with less than normal sunshine this year. In country. all other regions, except those to the east of Strong winds occurred for 38 percent of the the ranges (excluding Southland) it was also a midday readings, over the south of the South rather cloudy month. Record low hours of Island, for the period 1 January to 30 Septem- bright sunshine were recorded not only in ber, which was the highest frequency there Auckland, but also in many places further since records began in 1956. south and west of the ranges of the North Rather dry conditions prevailed in Canter- Island. Only 90 hours (57% of normal) was bury and North Otago, due to persistent west- recorded at Auckland City and 105 hours (65% erlies. Only 1 mm was recorded at both of normal) at Kelburn, being the least since Oamaru Airport and Harbour. These records began in 1962 and 1930 respectively. were the lowest since records began in 1941 October was, in most places, a rather windy and 1943 respectively. Many other places in and warmer than normal month. Canterbury and North Otago recorded less A marked feature of the weather in Octo- than 10 mm. Only 243 mm was recorded for ber, was an almost continuous series of west the year to 30 September at Christchurch or north-west airstreams which affected New Airport. This was the second driest for that Zealand. These were due to a steady passage period; the driest was in 1982, with 237 mm. of anticyclones which passed to the north of The six months ending September, at Christ- the country, and also many deep depressions church Airport, with 164 mm was the driest which tracked to the south. The only signifi- for that period since records began in 1944. cant, though brief break in this regime, was on Rainfall totals were about twice normal in the 21st, when a trough of low pressure, which had moved eastward on to New Zealand, was Hawke's Bay, much of Manawatu and in Fiordland. As much as 1085 mm was recorded followed by cooler southerly conditions. at . This was the second highest The persistent west to north-west air- since records began in 1930. The total of 148 streams associated with the generally large mm (231% of normal) recorded at Napier pressure differences from north to south con- Airport was the highest since records began in tributed to making October rather windier 1950. Rainfall totals of 129-180 percent of than average in many places. There were 29 normal were recorded in southern Wairarapa, days with wind gusts of at least 63km/hr (34 Wellington, Westland and Southland. knots) recorded at Kelburn, which was the As a whole, New Zealand experienced the most for any month, for at least 21 years. A warmest September ever recorded. The mean total of 13 days were recorded at Christchurch temperature, calculated from 7 indicator sta- Airport (the most since an equal number of tions was 11.9°C which was 1.6°C above the days in October 1968), and 22 days at Inver- normal. The previous record was 11.6°C in cargill Airport, which was the most for at 1969. Mean daily maximum temperatures least 35 years. North-west winds were record- were 2.5-3°C above normal in Gisborne, ed for 64 percent of the midday observations Hawkes Bay and north Canterbury. At Christ- at Invercargill, which was the third highest church Airport they were 3.2°C above (being frequency in October in 32 years of record. even higher than the normal for October) and Mean sea level pressures were excrptional- the highest since records began in 1953. ly low over the south of the South Island. The Temperataures were near normal in Fiord- average 9am reading for the month at Inver- land and about 1°C above in Westland. In most cargill Airport was only 995.5 hPa, some 15.2 other places they were 1.5-2°C above normal. hPa below average, and the lowest for any A grass minimum temperature of -8.5°C month since records began in 1948. They were was recorded at Christchurch Airport on the also very low over the North Island, where morning of the 9th. This was the lowest since Kelburn the average of 1004.5 hPa (9.2 hPa records began in 1953. below a verage) was the lowest recorded in October since 1898. Once again it was cloudier than normal in Northland and Auckland, where in most Rainfall totals were above normal in most places it was the fifth consecutive month with western regions of New Zealand south of New Zealand Weather 35

Auckland, in Nelson and in much of Southland. warmest October since 1962, when 13.4°C was Rainfall was about twice normal in Buller and recorded. Mean daily temperatures were Westland, but it wan particularly wet in South about 2-3°C above normal in eastern regions Westland and Fiordland, where in some places of both islands. They were 3.5°C above at totals were three to four times normal. Rain- Napier Airport, 3.2°C above at Kaikoura and fall totalling 1351 (373% of normal) recorded 2.9°C above at Christchurch Airport. Mean at The Hermitage was the highest in October daily maximums of 21.7°C (4.9°C above norm- since records began in 1930. A total of 1912 al) and 22.8°C (4.8°C above normal) were re- mm (351% of normal) was recorded at Mil- corded at Christchurch and Napier Airports ford Sound, which was also the highest record- respectively. These were equivalent to mid- ed there in October since records began in summer mean daily maximum temperatures 1930. This also appears to be the highest and were due mainly to the high frequency of rainfall total ever recorded in October in New north-west days. It was cooler than usual Zealand. A total of 3709 mm was recorded though in Westland and Fiordland, where there in the last three months, which is also mean temperatures were about 0.5-1°C below another record for this period in New Zealand. normal. Temperatures werenear normal in Rather dry conditions continued to prevail Southland and central Otago. Elsewhere they in drought affected Canterbury and North wre 1-1.5°C above normal. Otago. Some stations recorded very little rain Again, it was cloudier than normal in west- over the the months, August-October. Some ern regions of New Zealand, south of Auck- of these were 22 mm at Oamarn (township), 25 land. Hours of bright sunshine were less than mm at Timary Gardens and 29 mm at Palm- 70 percent of normal along the West Coast of erston North. Only 26 mm was recorded at the South Island. Hours of bright sunshine Oamaru Airport, which was the lowest in 48 were 110-120 percent of normal in Northland, years of record. A total of 35 mm at Middle- Auckland, Bay of Plenty, Gisborne and march was the lowest since 32 mm in 1929, Hawkes Bay. Elsewhere they were near and 36 mm recorded at Waimate was the normal. lowest for this period since recorded began in 1898. A break in the persistent west to north-west conditions occurred after the first week of In October, rainfall was, in eastern regions November. Northeasterlies were more fre- from Gisborne to Otago (including Welling- quent than usual in November over the north ton), only about 20-40 percent of normal. The of the North Island. 15 mm (22% of normal) recorded at was the lowest in 52 years of record. Rainfall totals were 120-160 percent of Only 5 mm (8% of normal) was recorded at normal in much of Bay of Plenty and Nelson. Kaikoura, which was the lowest in 40 years of About twice normal rainfall was recorded at record, 8 mm (16% of normal) at Timaru . It was a little wetter than normal in Gardens, 9 mm (21 % of normal) at Christ- Taranaki, Wanganui, Wellington and Wairara- church Airport, and 10 mm (26% of normal) pa. Totals were less than 70 percent of normal at Oamaru Airport. A total of 23 mm (46% of in Auckland, Gisborne, inland areas of Canter- normal) was recorded at . bury and in southern Otago. Only 27 mm (36% This was equal to 23 mm in 1963 when records of normal) was recorded at Lake Coleridge. In began. Rainfall was about 45-60 percent of other areas of Canterbury and Otago they normal in Bay of Plenty and 60-75 percent of ranged from 80-95 percent of normal, which normal in Northland. helped a little to relieve the prevailing Only 252 mm were recorded in the year to drought conditions. At the end of November 31 October at Christchurch Airport, which was only 291 mm (49% of normal rainfall) had the lowest for that period since records began been recorded at Christchurch Airport, which in 1944. was the lowest since records began in 1943. Once again much of New Zealand experi- Temperatures were again much warmer enced another warmer than normal month. than normal over New Zealand. The average The average New Zealand temperature was New Zealand temperature was 15.2°C (1.4°C 13.2°C (1.1°C above normal). This was the fifth above normal), being equal to November 1954. warmer than normal month in a row, and the The only other warmer November was that of 36 New Zealand Weather

1892, with 15.3°C. Mean daily temperatures totals ranged from 80-90 percent of normal. It were 1°C above normal in most places, 2°C was sunnier in the Central Otago, Mackenzie above in western regions of the North Island, Basin area, where totals ranged from 110-120 in Canberbury and Otago and 3°C above norm- percent of normal. Elsewhere they were near al at The Hermitage (Mt Cook). A maximum normal. of 31.3°C was recorded at Napier Airport, in Many thanks are due to the New Zealand fine northwesterly conditions, on the 4th. Meteorological Service for providing the cli- Rather cloudy conditions prevailed in matological data from which this summary Northland and Auckland (where totals were was compiled. only 70% of normal). It was also cloudier in — S. Burgess Waikato, Bay of Plenty and Gisborne, where