1 August 2013
NIWA SEASONAL CLIMATE OUTLOOK AUGUST-OCTOBER
A warm early spring on the cards
Temperatures over the August to October period as a whole are very likely to be above average in the North Island
regions as well as in the north of the South Island, and likely to be average or above average in the east and west of
the South Island.
Nevertheless, cold snaps, frost and snow conditions will of course still occur in many areas from time to time, as is
typical of this time of year. Sea surface temperatures are also forecast to be above average along the east coast of New
Zealand and further offshore, with conditions close to average to the west and in the Tasman Sea.
Rainfall for the August–October period as a whole is forecast to be normal or above normal in the east and north of the
North Island as well as the west of the South island, while normal or below normal rainfall is likely for the west of
the North Island and the north of the South Island.
Normal rainfall is expected for the east of the South Island. Soil moisture levels and river flows are likely to be
normal or below normal in the north of the South Island and the west of the North Island, normal or above normal in the
north and east of the North Island as well as the west of the South Island. Normal soil moisture levels and river flows
are forecast for the east of the South Island.
The equatorial Pacific Ocean remains in a neutral state (neither El Niño nor La Niña) despite some patterns reminiscent
of a weak La Niña. International guidance indicates that neutral conditions are the most likely outcome over the coming
three months.
For the New Zealand region, higher pressures than normal are forecast south of the country, while lower pressures than
normal are expected to the north over Australia and the Coral Sea. This circulation pattern is expected to produce a
weaker than normal westerly flow over New Zealand.
Overall picture
Rainfall, soil moisture and river flows
Rainfall for the August–October period as a whole is forecast to be normal or above normal in the east and north of the
North Island as well as the west of the South island, while normal or below normal rainfall is likely for the west of
the North Island and the north of the South Island.
Normal rainfall is expected for the east of the South Island. Soil moisture levels and river flows are likely to be
normal or below normal in the north of the South Island and the west of the North Island, normal or above normal in the
north and east of the North Island as well as the west of the South Island. Normal soil moisture levels and river flows
are forecast for the east of the South Island.
Temperature
Temperatures are very likely to be above average in the North Island regions as well as in the north of the South
Island, and likely to be average or above average in the east and west of the South Island.
Nevertheless, cold snaps, frost and snow conditions will of course still occur in many areas from time to time, as is
typical of this time of year.
Sea surface temperatures are forecast to be above the climatological average for the coming three months along the east
coast of New Zealand and further offshore, with conditions near average to the west and in the Tasman Sea.
More: August.pdf