The 2011 New Zealand snowstorms were a series of record breaking snow falls that affected both the North Island and South Island. The storms occurred over the span of a few weeks, beginning on 25 July 2011 in the North Island and subsequently spreading to the South. The storms subsided in late July and returned in August. It was the worst winter storm to hit New Zealand in seventy years. The heavy snowfalls caused widespread closures in many cities, including Christchurch, Wellington and Dunedin. The South Island was the hardest hit, although the North Island was significantly affected, with the climatically mild cities of Auckland and Wellington reporting the first notable snowfall in over twenty years. The storms caused chaos around the country, leaving people stranded at airports, blocking state highways and resulting in entire regions, particularly Canterbury and Otago, being completely closed. The initial storm of July was relatively short lived, only to return again in August. The winter storm also caused mixed precipitation. The snowfall was caused by Antarctic storms which moved northward. A large high pressure system had developed and stretched from Antarctica to the subtropics, where it had then merged with three neighbouring low pressure systems, causing cold temperatures and heavy snowfall. 25 July 2011 On 25 July 2011, New Zealand was gripped by its coldest winter snap in fifteen years. The lowest temperature set during the month was at Manapouri (in the southwest corner of the South Island) on 26 July, which was a new all-time record for the town. Christchurch Airport recorded its second-coldest day on 25 July. The severe winter storm was well predicted, with forecasters warning of the potential of heavy snow down to sea level in south and east of the South Island and to low levels in the North Island. This snowstorm was especially threatening as it was the school holidays, and many people were travelling. Up to of snow was recorded in parts of Christchurch, the heaviest recorded there in sixteen years. The snowfalls also flattened sand dunes in Brighton and completely coated nearby Sumner Beach 1,700 homes within the Christchurch metropolitan area were without power. The city's bus service was also shut down for almost two days. Various highways were closed, including parts of State Highway 1 between Invercargill and Dunedin and State Highway 94, the road from Te Anau into Milford Sound. The storms lasted for roughly