Niwa still has sunny outlook for winter and spring ahead

Southland farmers are hoping for good news after harsher than expected weather in June. Picture / Simon Baker

What a difference a snowfall makes.

One month ago the National Institute of Water and Atmospheric Research (Niwa) predicted winter temperatures were likely to be warmer than normal in most areas throughout the country.

June temperatures in the North Island and northern South Island were forecast to be average or above, while the rest of the South Island could expect normal temperatures, Niwa said.

Rainfall, Niwa predicted, was also expected to be normal or above normal across the country.

One month later and with parts of the country waist deep in snow, battered from galeforce winds - and a tornado - and drying out after flooding, Niwa has now revised its original forecast for July in an understated way, saying it was "likely to be colder and frostier than normal".

However, Niwa has not lost its sunny optimism and has continued to forecast the next three months were likely to see average or above average temperatures overall.

New Zealanders and newborn lambs could look forward to a "mild start to spring after a cold winter", Niwa forecasted today.

Dr Jim Salinger, of Niwa's national climate centre in Auckland, said it was not Niwa's role to make day to day forecasts but instead to use the considerable research available to it to determine climate outlooks for the weeks ahead.

Despite the first major snowfall of the season coming a week after the initial relatively mild June forecast was released, Dr Salinger maintained the public could have faith in the accuracy of the climate predictions.

"We also look at the probability of things happening based on our research and it may be determined that based on our forecast there is a 50 per cent probability of it happening."

Despite failing to forecast a severe winter was just around the corner for much of the country, Dr Salinger denied the weather forecast was down to chance and said Niwa had predicted there would be some cold winter weather "outbreaks" over the three months.

"Lots of people use our outlooks and rely on our forecasts for their planning."

Niwa has forecast temperatures in July were likely to be average in the north of both islands and average or above average in other regions.

However, people could expect further "cold outbreaks typical of winter will occur from time to time" .

Rainfall was likely to be normal throughout the country.

- NZPA