Last year was the fourth-warmest on record and closed with regions including Waikato, Northland, Bay of Plenty and Hawke’s Bay falling significantly short of their annual rainfall totals.
Tauranga recorded 787mm, well short of its annual average of 1200mm with several other main centres similarly short.
NIWA’s annual climate survey found temperatures were .5C-1.2C above the long-term average with Bay of Plenty and Hawke’s Bay even higher when compared to records that stretch back over 110 years.
The annual rainfall figures were 50-80% below normal throughout Northland, Auckland, Bay of Plenty, Waikato, Marlborough and Wairarapa but on the West Coast and in western Southland rain surged to 120-150% above normal. Meantime, the rest of the country kept close to average.
Despite soil moisture levels being near normal last winter things began to dry out by spring for much of the upper and eastern North Island, a trend that has continued into the new year, enhancing the usual dry conditions experienced over summer.
MetService meteorologist Lisa Murray said the data reflects a continuing warming trend with five of the last seven years being among the hottest recorded.
“The knock-on effect of this is we start 2020 with many eastern and northern regions of the country thirsty for some significant rainfall.”
The dry conditions were worsened through 2019 by westerly winds that were stronger than normal all year while contributing to wetter conditions on the West Coast. The pattern was expected as a result of climate change.
NIWA’s soil moisture deficit index indicates soils through almost all Northland, Hauraki Plains, north Waikato and southern Hawke’s Bay are classed as dry and well below their historical average deficits for mid January.
In keeping with climate predictions the West Coast is receiving increasingly intense rain and last March experienced up to 1100mm of rain in only two days.
Weather Watch meteorologist Philip Duncan said the expectations he had in September for NZ to have a dry, even drought-prone summer are starting to be proved correct.
“As early as September we were feeling the influence of these big highs that have dominated Australia’s weather. From Waikato through to Northland, in particular, those high-pressure systems have stopped rainmakers coming from the tropics and have also stopped the southern systems coming all the way north.”
He sees little prospect of change through the rest of January.
“Ironically, Australia is likely to receive quite good rain across New South Wales and Victoria in coming days but we will get the opposite of that.”
Duncan said in some respects 2019 proved to be an ideal year for many farmers with reasonable rain until spring and generally warm growing conditions.
“But now things are really starting to dry out.”
