Current climate: May 2018

Overall, mean sea level air pressures were much lower than normal over and to the south of New Zealand during May.  The first half of the month was relatively warm and dry throughout the country.  However, during the second half of May, a blocking anticyclone became established over the southeast of Australia.  This delivered a prolonged period of disturbed west and southwesterly winds over the country.

Temperature

May temperatures were well above average (> +1.20°C) in parts of Hawke’s Bay.  Temperatures were above average (+0.51°C to +1.20°C) for most remaining parts of the North Island, except Northland, Taranaki and Wellington where temperatures were near average (-0.50°C to +0.50°C).  May temperatures were above average in Nelson and coastal Canterbury north of Ashburton, and below average (-0.51°C to -1.20°C) in parts of Southland.

Rainfall

Rainfall was well below normal (< 50%) for coastal south Canterbury and north Otago.  Below normal rainfall (50-79%) was recorded in the western Bay of Plenty, Hawke’s Bay, Wairarapa and eastern Otago.  Rainfall was well above normal (>149%) for parts of the eastern Bay of Plenty, Taranaki, Manawatu, Marlborough, and Kaikoura.  Above normal rainfall (120-149%) was observed in parts of Waikato, Whanganui, and north Canterbury.

Soil Moisture

As at 1 June 2018, soil moisture levels were above normal for the time of year for eastern and inland parts of the South Island north of Southland, and southwestern parts of the North Island.  Soil moisture levels were generally near normal for the time of year across the remainder of the country.

Percentage of normal rainfall for May 2018
End of month water balance in the pasture root zone for an average soil type where the available water capacity is taken to be 150 mm.
Departure from average air temperature for May 2018.