What happens when you reach the coldest point of the year but have a mild air flow moving in? You challenge the entire season’s records and you run the chance of an early start to spring, especially if it lingers long enough.

WeatherWatch.co.nz measures the seasons by weather patterns and how nature is reacting to them, as well as the time of the year we are in. Nature in New Zealand doesn’t always match the astronomical or meteorological seasons. Our location on earth and geography of our country means New Zealand tends to have 8 months of Autumn/Spring weather and 4 months of winter/summer, in our minds.

Traditionally the coldest period of the year nationwide is a month after the shortest day (which is in late June), so that is smack bang now (second half of July and first half of August, plus or minus a couple weeks). The warmer it is now the less likely we are to see further long extended runs of cold frosty weather day after day, because New Zealand often gets windier more spring-like weather arriving from mid August onwards and that stops the nights from being so cold.

WeatherWatch.co.nz says the next week or two are dominated by westerly quarter winds which will see few frosts and encourage more rain, especially in northern and western parts of the country. There will even be a few days with sub-tropical and Australian air flows. However there is still the chance of a Southern Ocean southerly later next week, but the chaotic patterns indicate even if we did get a polar snap it might be very short lived.

WINTER IS NOT OVER…YET
When we talk about an early start to spring weather we don’t mean that is the end of winter. In fact spring is all about winter *slowly* fading away, but the word “fading” is key. We may already be see winter weather fading in some areas now due to this early arrival of westerlies. For example, the upper half of the North Island isn’t showing overnight lows that reflect the depths of winter. Hamilton’s overnight lows are closer to +10 than 0 in the week ahead, often Waikato is a frosty region in winter but not so much this year.

However, major frosts and snow events CAN occur not only in August but also in September and October too. In fact it was mid August in 2011 that heavy snow fell in Wellington city and snow flurries fell as far north as Auckland city and the Northland ranges. That’s unlikely to occur this year but, in the chaos of Southern Ocean weather, we cannot rule out a significant Antarctic blast.

Around Southland and Otago there are still many cold winter days and nights ahead but double digit highs and above zero overnight lows are also in the mix in the next 10 days, which isn’t too rough for the dark depths of winter.

So, we’re not saying the wintry weather is all over, but we are saying the signs that spring is just around the corner will be increasingly noticed in the days and weeks ahead, despite the long nights at this time of the year. In fact, the days are now slowly getting longer so if you’re an early riser or someone stuck in traffic at rush hour you may notice the little extra bits of daylight in the next couple of weeks, if you haven’t already.

– Written by head forecaster Philip Duncan, WeatherWatch.co.nz