May 2017 – A drier than normal May on the horizon for many
Lows made frequent forays across the North Island during April, with Cyclone Cook a notable arrival on 13-14 April. The
atmosphere was locked in a repeat pattern during April, with low pressure bee-lining towards Cape Reinga and producing
intermittent heavy rain and high humidity across most of the North Island. More easterlies than usual were also seen
over the South Island during the month. April rainfall ranged between 200% and 350% of normal over the entire North
Island and the north and east of the South Island.
“A sopping wet April followed hard on the heels of an extremely wet March, for regions in the north and east of both
Islands,” said MetService meteorologist Georgina Griffiths. “It was the wettest March-April period on record for
Auckland, Tauranga, Hamilton and Whakatane. It was the second-wettest March-April period on record for Christchurch, and
the third-wettest March-April period for Wellington.”
Auckland recorded 439mm of rain during March and April, the highest since records began at the Airport in 1962. Tauranga
saw 569mm (records since 1898), Hamilton observed 427mm (records began 1935), and Whakatane clocked up 482mm (records
since 1974). Christchurch experienced 234mm during the two-month period (records since 1943), while Wellington recorded
360mm (observations since 1928).
Looking ahead to May, change is in the wind. “The atmosphere is finally changing gear,” said Griffiths. “Expect a change
away from constant lows on the weather map, towards high pressure frequenting the New Zealand region.” At this time of
year, this equates to a recipe of high pressure sitting over the country for longer than usual, in between mobile
westerly fronts. A drier-than-usual May is forecast for most of the country, except for Wairarapa, Hawke’s Bay and
Gisborne (where closer to normal May totals are predicted).
While May starts off colder than normal, temperatures are expected to bounce back, with a forecast of above-average
temperatures across the country during the second half of the month.
ends