Weather Watch: Our landscape dictates a range of weather systems

Auckland's weather could be attributed to its lack of significant ranges. Photo / Richard Robinson

The mountains and ranges that help create our nastiest floods are also the very things that give New Zealand its world famous environment and diverse weather.

When you look at a map of the world, it's hard to believe our two main islands are at a latitude that can support people wearing shorts and T-shirts even in winter. Our ranges play a big part in this - acting as walls to stop bad weather from advancing to all regions. Conversely, they hold up bad weather, sometimes making it more intense where it hits.

The Chatham Islands has a reputation for being a windswept place to live - yet it shares the same latitude as Canterbury, a region known for snow, yes, but also 40-degree temperatures in summer and droughts.

If we could smooth out the Southern Alps, remove the main divide up the North Island's East Coast, flatten Central Plateau and make all of our hills no higher than the Chatham Islands (mostly sea level to a couple of hundred metres) what would the weather in New Zealand then be like?

Fewer systems would linger and the weather from region to region would be similar.

Think about this: The sou'west flow in Auckland can be relentless at times. That's because a sou'wester in Auckland has no significant ranges to pass over when it comes - and nothing north-east of the city to hold up the rain clouds. Now imagine that type of weather everywhere.

Fiordland would kiss goodbye the massive rainfall totals that make it one of the wettest places on earth.

Likewise, Central Otago would say goodbye to extra hot summers and the lowest rainfall in the country.

Wellington would no longer be the windiest city - chances are Invercargill might be. The Southland city is currently sheltered by the towering mountains of Fiordland and up towards Queenstown. With them gone, the Southern Ocean storms would roar past pushing week after week of strong westerlies.

Gisborne and eastern Coromandel, along with Bay of Plenty and the Bay of Islands, would have similar weather to the more rugged West Coast beaches.

Mountain ranges mean we have to take the good with the bad. They're why it's tough to forecast here - and I wouldn't have it any other way.