Written by John Law, Meteorologist

If you look back to the Towns & Cities forecast tabs or the Rural forecasts, you will notice that at the bottom of the 10 day forecasts is this phrase: “Forecasts and temperatures for days 1-5 are produced by MetService meteorologists. Forecasts and temperatures for days 6-10 are automatically generated by MetService's computer weather modelling system.”

New Zealand is great for outdoor sports. Sometimes the weather is too. With summer approaching and long weekends on the calendar, the time is ripe for packing cars and heading off into the great outdoors. But how do you know if the weather is going to be any good when you’re planning a trip, particularly to places ‘off the beaten track’? This blog post is about how you can get a better idea of the weather in areas not covered by regular forecasts - the types of areas frequented by rock climbers, mountain bikers, kayakers etc.

It can be tricky here in New Zealand to fit all the weather for a day in just a few short sentences. Here are some phrases that you will often find in our forecasts and what they mean.

Wet Weather

Sitting out in the middle of the ocean, New Zealand is vulnerable to extremes of weather from all directions; from the remains of tropical systems barrelling in from the north, to cold winter southerlies bringing a blanket of snow.

As New Zealand’s designated national meteorological service to the World Meteorological Organisation (WMO), it is MetService's responsibility to provide clear, concise and timely warnings of severe weather that is likely to affect New Zealand.

What defines severe?

We remember our war dead on Anzac Day, 25th April, the anniversary of the landings at Gallipoli in World War I. But our heaviest losses in that war occurred on the Western Front. Our worst day was 12 October 1917 – the First Battle of Passchendaele. New Zealand lost 1,000 soldiers in two hours because the high command ignored the effect of heavy rain on the battlefield. The Ypres Salient, in Belgium, where the campaign took place was low lying. Prior to the war the water table was 35 centimetres below the surface.

When recruiting and training people to become meteorologists, MetService requires that trainees hold a university science degree in maths and physics. Why maths and physics? First and foremost, meteorology is a science, and we need people in our National Forecast Centre who are capable of applying the scientific thinking that they’ve developed at university to understand the state of the atmosphere. Let’s look at specific examples of why maths and physics are important to meteorology.  

The physics of fog

June 21st is the Northern Solstice and marks the shortest day here in the Southern Hemisphere.  On the 21st the sunrise is around 7:48am and sunset 5:00pm in Wellington, giving just over 9 hours of potential sunshine for the capital. The timing of sunrise and sunset varies from location to location, sunrise in Gisborne being almost an hour earlier than in Invercargill.  You can find the sunrise and sunset times on the forecast pages at www.metservice.com, just underneath the towns and cities forecasts.

What would New Zealand’s history be like without the First and Second World Wars? Blame the terrible Russian winter and Napoleon’s folly according to historian Adam Zamoyski in his riveting book 1812 Napoleon’s Fatal March on Moscow. The losses suffered in the invasion, particularly to his cavalry, ensured Napoleon’s downfall the following summer. That led to an aggressive Germany unified under a militaristic Prussia while in Russia, the Tsar came to believe he was God’s instrument on Earth.