Gales to give way to cooler, calmer weather

Severe gales overnight are expected to subside this morning, bringing much calmer and cooler weather to the South Island over the next few days.

MetService meteorologist Andrew James said it was even possible rain showers would fall occasionally across the South Canterbury high country, where a large fire is burning near Lake Ohau, Otago, Southland.

Last night’s severe northwesterly gales reached more than 100km/h in exposed parts of the South Island, and were caused by a major front passing over, he said.

The winds brought temperatures up to 25 deg C yesterday, but the wind was expected to turn southerly today, bringing cooler air and showers.

"After that front goes through, we’ll have a few days of settled weather.

"Cooler air moves in with this front and a ridge develops — the perfect set-up for frosty mornings."

Temperatures were expected to dip as low as -1degC in Central Otago on Thursday, prompting a warning to growers to watch out for frosts.

James said severe weather watches had been issued for heavy rain about the West Coast and the ranges, but those on the east coast should expect only a few showers over the next few days.

"Whether the rain is enough to do anything to the Ohau fire is not my expertise.

"But the firefighters will certainly be pleased when the northwest gales are gone, because the strong, dry winds will not be doing them any favours."

James said another system was set to move in this weekend, and winds were expected to pick up again during Friday.

This changeable pattern was typical of the season, he said.

"Spring is the windiest season. Winds are driven by temperature difference over a large scale.

"At this time of year, the northern part of the southern hemisphere warms up much faster than the Antarctic, leading to the largest temperature differences, and hence the strongest winds.

"These strong westerlies move fronts over New Zealand at a rapid pace, so spring is typically changeable."

john.lewis@odt.co.nz