For the climes they are a changin'

By ANDREW LAXON

No, it isn't just your imagination. The weather really has been unsettled, swinging unpredictably between hot and cold and dry and wet, with the odd hailstorm or torrential downpour for good measure.

Climate analysis released by the National Institute of Water and Atmospheric Research (Niwa) yesterday shows many records and extremes, from the coldest July in more than 30 years to five unusually warm months in May, August, September, October and December.

Conditions also varied dramatically from region to region. While South Islanders complained of drought, North Islanders were often hit by severe rain and floods.

So to settle those long-running arguments at work and home once and for all, here are the official answers to 10 of our most common views on the past year's weather.

1. It hasn't stopped raining this summer

More or less true if you live in the upper half of the North Island. Auckland received 187mm of rainfall last month, more than double the average for December.

Rainfall hit record highs at Kerikeri, Motu in the eastern Bay of Plenty, Mahia in northern Hawkes Bay, Turangi and Masterton.

The Manukau Heads, New Plymouth, Taumarunui, Napier, Wanganui and Wellington recorded their second-highest levels.

It was different in most of the South Island, where parts of Canterbury and Southland continued to have below-average rainfall.

2. It always rains at the weekend

This sounds like selective memory at work, but it has been true for 16 weeks in a row (even though the weekend before Christmas was generally fine in most places).

As the Herald reported last month, rain has arrived with depressing regularity on Fridays and Saturdays, washing out half a season of cricket and wiping out five of seven speedway races at Western Springs in the worst season in 72 years.

The pattern has continued with one bright spot - the midweek public holidays of Christmas Day, Boxing Day, New Year's Day and January 2 were sunny.

3. It rains more in Auckland anyway

False, especially if you come from the north side of Mt Egmont/Taranaki, which retained its title as the wettest place in New Zealand with 7546mm of rainfall. (Milford Sound, traditional touchstone for heavy rainfall, managed only 5134mm.)

It is true that Auckland was the wettest of the five main centres at 1256mm, but Hamilton was not far behind with 1192mm. Wellington recorded 1053mm, and in the drought-plagued south Christchurch and Dunedin had only 405mm and 515mm respectively.

Several other major North Island cities had more rain than Auckland. MetService records show 1633mm of rain fell in Whangarei, 1564mm in Rotorua and 1554mm in supposedly sunny Tauranga.

Yesterday's Niwa report shows Whakatane had the fewest hours of sunshine last year since records began there in 1957.

4. The weather wasn't too good last summer either

True for the top half of the North Island, despite a late rally in March when temperatures climbed back into the mid-20s.

Of 17 towns and cities measured for summertime sunshine hours, Auckland ranked 15th with 565 hours. Kaitaia was 12th (621), Whakatane 13th (601) and Taumarunui 17th (512). As usual the sunniest places were Nelson (878) and Motueka (831) although many locals would have preferred rain to break the drought.

5. Nelson is always the sunniest place in New Zealand

True again across the whole of last year, as well as last summer. Nelson, Blenheim and Motueka held their position as the sunniest places.

Most of the country would be stunned to learn that Wellington was the sunniest main centre with 2094 hours, marginally ahead of Christchurch (2072) and well in front of Auckland (1981). No records were produced for average daily wind.

6. Summers used to be much sunnier and more settled

This sounds like more selective memory - combined with nostalgia - but Niwa senior climate scientist Dr Jim Salinger says it is probably true.

From the mid-1970s to 1998, a 20-year weather pattern brought mainly westerly and southwesterly winds to New Zealand.

Dr Salinger says that in the past three years this pattern has changed, bringing more easterlies and northeasterlies "and that definitely happened last year".

6. It was too hot to sleep last month

True. Most of the North Island had the highest average overnight temperatures on record. In Auckland they were about 16 degrees, more than two degrees higher than normal. The cause was persistent cloud and moist northerlies.

7. These crazy weather patterns are caused by global warming

False. Though it is true global warming plays a part in long-term weather changes.

Dr Salinger noted yesterday that the weather was staying warmer for longer in the northern part of the country. Other telltale signs were that subtropical grasses had turned up farther south and frosts were less common than 100 years ago.

But the more immediate causes of extreme, unpredictable weather were different winds from New Zealand's changing long-term weather pattern and the presence or absence of the short-term weather cycles, El Nino and La Nina.

The previous La Nina faded out early last year, resulting in more anticyclones across the South Island for the first nine months - and worsening of the drought.

Weather in the North Island was wetter because of frequent lows coming across the Tasman and stormier because of warmer sea temperatures.

8. Last winter was much colder than usual

Mainly true, although it depends which month you choose to recall.

There were severe cold snaps in late May and June before the country had its coldest July for more than 30 years.

The national average temperature of 6.8 degrees was almost one degree below the 1961-90 normal and the lowest for July since 1969.

But August - despite a severe snowstorm which buried Ohakune under 30cm of snow - turned out to be the sixth warmest since reliable measurements began in the 1850s.

The warmer temperatures continued into spring. October was the third warmest on record, with average temperatures of 16 in Auckland.

9. At least it was a better year for skiers

True, but it wasn't as good as the early hype made out. Ruapehu had its biggest snowfall for 20 years in late July, and Whakapapa and Turoa their best cover since 1995.

But it was still below the average for the past 10 years and did not compare with the bumper early 90s.

10. This year has to be better

Firm answers to this one in another 12 months.

For those of you still willing to trust the forecasters, Dr Salinger says an El Nino could return this year, bringing westerly and southwesterly winds which would create drier conditions in the north and east but more wet weather in the south and west.