Outlook: July-September 2018

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July – September 2018 temperatures are forecast to be near average (40% chance) or above average (40% chance) for the North Island and north of the South Island.  Near average (45% chance) temperatures are expected for the east and west of the South Island.  Periodic easterly quarter (SE to NE) flow may bring mild periods, especially to northern areas. Westerly quarter (NW to SW) winds will increase the risk for cold snaps, particularly for the South Island during mid-July.

July – September 2018 rainfall totals are forecast to be near normal (35% chance) or above normal (40% chance) in the north and east of the North Island.  Normal (40 – 50 % chance) rainfall is forecast in the west of both islands as well as the north of the South Island with near normal (40% chance) or below normal (35% chance) rainfall expected in the west of the South Island.  Lower than normal air pressure to the north and east of New Zealand during may bring a few heavier rain events to the north and east of the North Island and perhaps east of the South Island, potentially during late-July.

July – September 2018 soil moisture levels and river flows are expected to be above normal (45% chance) for the north and east of the North Island, with an equally likely chance (30-35%) of normal or above normal conditions for the west of the North Island. For the north of the South Island, soil moisture levels and river levels are equally likely to be near normal or below normal (30-35% chance).  For the east of the South Island, soil moisture levels and rivers flows are equally likely (40% chance) to be near normal or above normal with below normal soil moisture levels and river flows likely (45% chance) for the west of the South Island.

 

Graphical representation of the regional probabilities, Seasonal Climate Outlook, July-September.