Weather and Climate (1991) 11: 31-36

BRIEF REVIEW OF WINTER ANDSPRING 1990

WINTER 1990 (Fig. 1)Winter 1990 was very dry in the far south.

Northeasterlies brought sunny conditions toSouthland and above average temperatures tothe entire country. In most other regions i twas cloudy and wet.

Coastal Southland, South Otago and Dun-edin recorded less than 60 percent of averagewinter rainfall. Record low rainfall for theseason of 132 mm (56 percent of average) wasmeasured at Invercargill Airport where meas-urements began i n 1939. Rainfall totalling

80

NEW ZEALAND WEATHER

RAINFALL

percentage of normal(1951-80)

WINTER 1990

Fig 1: Winter 1990. Rainfal l map based on observationsfrom 43 stations; temperature departure map based onobservations from 36 stations; sunshine based on observa-tions from 16 stations.

78mm (57 percent of average) was recorded atDunedin Airport, which was the lowest for theseason since 72mm in 1970.

Overall for New Zealand, the winter of 1990was the 7th warmest since records began in1853. The average daily temperature for thewhole country during winter was 8.8°C, whichwas 0.7 degrees above average.

Temperatures have been much warmerthan average for all of the winters since 1984,with the exception of 1986.

Mean temperatures were 1.0 degrees aboveaverage in Gisborne and along the KaikouraCoast, and 0.4 to 0.9 degrees above average inmost other places.

The winter was wetter than usual over theremainder of New Zealand, especially in ar-eas exposed to the north and east. Rainfallranged from 120 to 150 percent of average in

+0.5

+0.5

+1 .0ABOVEAVERAGE

+1.0ABOVEAVERAGE

+0.5

+0.5

+0.5

31

+ 1 . 0ABOVEAVERAGE

TEMPERATURE

departure fromnormal(1951-80)

WINTER 1990

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Centre Rainfalltotal, mm

Percentageof normal

Year recordsbegan

Wellington 35 24 1862Paraprarumu

Airport 39 34 1945

SUNNY

SUNSHINE

percentage of normal(1951-80)

WINTER 1990

Auckland, Bay of Plenty, Rotorua, Nelson, andin the east of both Islands as fa r south asNorth Otago. Totals were well up in Napier(178 percent o f average) and Oamaru (167percent of average).

Southland had sunshine hour totals rangingfrom 10 to 15 percent above average. Sun-shine was about average in eastern regions ofboth Islands. In all other regions it was cloudi-er than usual.

The warmer and wetter conditions that pre-vailed in most areas in winter were caused byfrequent troughs of low pressure, and moreprevalent northeasterly winds associated withdepressions that crossed over the country.

MONTHLY HIGHLIGHTSJUNE 1990 - AUGUST 1990

June continued the trend this year of warm-er than usual weather. Northerlies broughtvery dry conditions to eastern regions of theSouth Island. In contrast, i t was rather cloudyand wet in the North Island from Taranaki toWellington, and on the west coast of the SouthIsland.

New Zealand Weather

It was very dry in Dunedin, and rather dryin a l l eastern regions o f the South Island,where rainfall totals ranged from 20 to 50percent of normal. Only 1 lmm was recordedat Dunedin Airport, which was a one in tenyear event. The lowest on record there forJune is 8mm. Rainfall was also low in North-land where about 60 percent of normal wasrecorded.

Rainfall was one and a half to two timesnormal in Fiordland, and up to one and a halftimes normal in Taranaki.

The average da i ly temperature f o r thewhole country was 8.7°C, which was 0.6 de-grees above normal. However, dai ly maxi-mum temperatures were well below normalin eastern regions of both Islands during coldsoutherly conditions from the 6th through tothe 14th.

Average temperatures were about 1.0°Cabove normal i n Wairarapa, Marlborough,South Canterbury and North Otago. In SouthIsland regions and the southern half of theNorth Island they were between 0.5 and 1.0°Cabove normal. Elsewhere they were nearnormal.

Near record high temperatures fo r Junewere recorded in Auckland on the 2nd, and inHawke's Bay on the 3rd: 20°C in Auckland,and 21.5°C in Havelock North, both 1 tpC belowthe highest ever recorded in these locations inJune.

Hours of bright sunshine were only 70 to 80percent of normal from Wanganui to Welling-ton, and 85 percent of normal in Westland. incontrast, it was very sunny in Gisborne, whichhad almost 25 percent more than the normalfor June.

July was also warmer than usual. I t wasrather dry in the south of the North Island andin eastern areas o f Canterbury, Otago andSouthland. Wetter weather continued on theWest Coast of the South Island. Heavy rainfalloccurred in Hawke's Bay during the last twodays of the month.

Record low rainfall for July was recordedat:

Rainfall totals ranged from 35 to 65 percentof normal i n eastern areas o f Canterbury,Otago and Southland. Heavy rainfall fel l in

New Zealand Weather

Rainfalltotal, mm

Percentageof average

Year recordsbegan

Rotorua 331 227 1899Kawerau 463 260 1954Riwaka,Motueka 533 351 1943Christchurch

Airport 171 313 1943Oamaru 144 369 1941

Hawke's Bay, during moist easterly condi-tions, on the 30th and 31st. More than 100mmwere recorded at Havelock North during theperiod. As a result totals in the region werealmost twice the July normal.

Auckland experienced t h e third equalwarmest July ever recorded and Wellingtonthe fourth equal warmest; mean temperaturesat these centres were:Centre

AucklandWellington

Meantemperature

12.4'C9.5°C

Departure Y e a rfrom normal records began

+1.2°C 1 8 6 2+1.1°C 1 8 6 2

The average daily temperature for thewhole country of 8.4°C was 0.8 of a degreeabove normal. Mean temperatures were 0.8 to1.2°C above normal in most regions. Theywere 1.3 to 1.6°C above normal in Aucklandand Waikato, and normal to half a degreeabove normal in South Westland, Fiordland,southern areas of Otago and Southland.

Extremely cold temperatures occurred atDunedin Airport during the early hours of themorning on the 20th and 21st. Grass tempera-tures at the Airport dropped to -12.9°C on the20th and -12.3°C on the 21st. Air temperaturesfell to -8.3°C on the 21st. These were thelowest temperatures recorded at Dunedin Air-port since measurements began in 1967.

Unusually high temperatures for July wererecorded along the Kaikoura Coast on the26th. They reached 21.8°C at Kaikoura, whichwas only 2.1 degrees below the New Zealandrecord of 23.9°C recorded at Hastings in 1942.

Hours of bright sunshine were mostly 10 to20 percent above normal in Wellington, Wai-rarapa, Canterbury, Otago and Southland.Cloudier than usual conditions were recordedin Auckland and Bay of Plenty where totalswere 80 to 90 percent of normal.

August was the eighth month this year withwarmer than average conditions. Extremelyhigh rainfall for August was recorded at Roto-rua, Motueka, Blenheim, and in much of Can-terbury and North otago. It was also very wetin Southern Hawke's Bay. In contrast it wasvery dry in Southland and Fiordland.

High winds attributed to a tornado, causedconsiderable damage to property in Inglewood(Taranaki) on the 12th.

Rainfall totals were two to three times theaverage for August at Rotorua, Kawerau, insouthern Hawke's Bay, Marlborough, and Can-terbury. 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:

SPRING 1990 (Fig. 2)

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Prolonged heavy rain caused severe flood-ing and a state of civil emergency in Motuekaon the 10th and 1 lth. Twenty six homes wereevacuated. A record high total for two days or286mm was recorded at Riwaka during theperiod.

Rainfall was below average in Westland,Fiordland, Central Otago and Southland. To-tals of lOmm (22 percent of average) and20mm (32 percent of average) were recordedat Queenstown and Invercargill Airportsrespectively.

The average temperature for the wholecountry of 9.2°C was 0.6 of a degree aboveaverage. Mean temperatures in most regionswere 0.5 to 1.0°C above average. They werenear average in areas o f Northland andOtago.

A few high temperatures for August wererecorded during the month. These were 19.6 'Cat Ohakea on the afternoon of the 6th (secondhighest since records began in 1940), and 20°Cat Franz Josef on the 23rd (highest sincemeasurements began in 1953).

It was cloudier than usual in many regions.Hours ranged from 55 to 70 percent of aver-age in Westland, and 70 to 80 percent ofaverage in Auckland, Waikato, Bay of Plenty,Wellington, Marlborough and Nelson.

Sunnier than usual conditions prevailed inFiordland, Southland and Central Otago,where hours were 10 to 25 percent aboveaverage.

The very dry conditions experienced duringwinter over the south of the South Island,continued into spring. Rainfall was well aboveaverage in Nelson and along the KaikouraCoast. These conditions were caused by morefrequent north to northeasterly airstreamsover New Zealand.

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100

ABOVEAVERAGE

NEARAVERAGE

110

100

SUNNY

110

NEARAVERAGE

100

SUNSHINE

percentage of normal(1951-80)

SPRING 1990

ABOVEAVERAGE

120WET

New Zealand Weather

RAINFALL

percentage of normal(1951-80)

SPRING 1990

Fig 2: Spring 1990. Rainfall map based on observationsfrom 46 stations; temperature departure map based onobservations from 40 stations; sunshine based on observa-tions from 17 stations.

Only 35 to 60 percent of average springrainfall was recorded in the Southern lakesarea of the South Island. The total of 72mmmeasured at Queenstown Airport (38 percentof average) was the lowest since records be-gan there in 1968.

Conditions were also drier than usual inFiordland, Southland, Central and SouthOtago, with total rainfall 60 to 80 percent ofaverage.

Rainfall was 50 percent more than averagein Nelson and Kaikoura. I t was also wetterthan usual in Rotorua, Manawatu, Wellingtonand South Canterbury.

Temperatures were close to average inmost places. However, i t was warmer thanusual by 0.5 to 0.8°C in Auckland, Waikato,Bay of Plenty, Gisborne, Hawke's Bay, SouthWestland and Fiordland.

Cantabrian's caught the sunshine, with to-tals 12 percent above average. In all otherregions hours were near average.

New Zealand Weather

MONTHLY HIGHLIGHTSSEPTEMBER - NOVEMBER 1990

September was very dry in eastern areas ofNorthland, from Horowhenua to Wanganui,and over the southern half of the South Island.More anticyclones than usual over southernregions of New Zealand brought above aver-age sunshine to many areas and below aver-age temperatures to much of the North Island.

Little significant rain was recorded in in-land areas of South Canterbury and North andCentral Otago, where in many places rainfallwas less than lOmm (15 to 35 percent ofaverage). Only lmm was recorded at Bendigo,being the lowest recorded there for Septembersince 1969.

Totals were 20 to 40 percent of average ineastern areas of Northland, and from Wanga-nui to Horowhenua.

However, more than twice average rainfalloccurred along the Kaikoura Coast.

September was the first month with lowerthan average temperatures over the NorthIsland since May 1988. The average for thewhole country of 9.9°C was OA 'C below aver-age, and the lowest for September since 1977.

Hours of bright sunshine were 20 percentabove average in Rotorua, Bay of Plenty andCanterbury. I t was also sunnier than usualover the rest of the North Island, and inMarlborough and Southland.

October was warmer than usual, especiallyin Auckland, Waikato and Gisborne. However,temperatures were below average in South-land and Otago where more rainfall thanaverage was recorded. Westerly airstreamspredominated, but winds from between northand east were more frequent than usual overmuch of the country. Winds from betweensouth and east were more frequent than usualover the south of the South Island.

Temperatures were 1.5°C above average inWest Auckland, much of Waikato and in Gis-borne. Over much of the remainder of theNorth Island and in Marlborough and Nelsonthey were 1.0 to 1.4°C above average.

The more frequent winds from betweensouth and east over Southland and Otago kepttemperatures there 0 .5 t o 1.0°C belowaverage.

Up to three times the average October rain-fall was recorded in inland parts of SouthCanterbury, and up to twice the average rain-

35

fall was measured in coastal regions of NorthOtago.

A total of 80mm of rain was recorded over-night at Rotorua from 6pm on the 14th, duringmoist northerly conditions associated with anactive front.

Drier than usual conditions prevailed inparts o f Northland, Taranaki, Buller andcoastal areas of North Canterbury where to-tals were as low as 50 percent of average.

Hours of bright sunshine were 10 percentabove average in Westland, Nelson and NorthCanterbury. However, cloudier than usualskies prevailed over the far north of the NorthIsland, in Waikato, Bay of Plenty, Rotorua,Taranaki and Southland.

November was very much wetter than usu-al in Marlborough and Nelson. In contrast,rainfall was well below average in Fiordland,Southland and about t h e MacKenzieBasin/Southern Lakes area. These conditionswere due to depressions passing over theNorth Island bringing more frequent east tonortheasterly winds.

Over twice average rainfall occurred inMarlborough and Nelson. Much of Nelson'srain fell during two 48-hour events. More than100mm was measured over the 1 lth and 12thin moist northerly conditions, and at least50mm over the 18th and 19th in similarweather.

Rainfall was twice average in Wellingtonand Rotorua. The total of 185mm recorded atRotorua was the fifth highest total for Novem-ber in 92 years of record.

Little significant rain fell in Southland andthe MacKenzie Basin/Southern Lakes area.Only 12mm (32 percent of average) was meas-ured at Waipiata (Maniototo). Totals were 40to 65 percent of average in Fiordland andalong the South Otago coast.

Temperatures were up to 1.5°C above aver-age in Fiordland, and 1.0°C above averagealong the remainder of the West Coast, inAuckland, Waikato and Southland. They were0.5 to 1 'C above average over much of theremainder of New Zealand, and close to aver-age in eastern regions from Wairarapa toOtago, including Wellington.

Temperatures reached 27°C at Haast on the13th, during warm southeasterly fohn windconditions. This was one of the highest tem-peratures ever recorded along the West Coastfor November where records began in 1866.

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Hours of bright sunshine were as much as25 percent below average in Marlborough andNelson, and 15 percent below average in Wel-lington and Rotorua. Sunnier weather pre-vailed in Wairarapa, Buller, and Fiordland,where totals were about 10 percent aboveaverage.

New Zealand Weather

Many thanks are due to the New ZealandMeteorological Service for providing the cli-matological information from which this sum-mary was compiled.

Stuart M. Burgess