When is it climate change, when is it just bad weather?

Monday, 11 May 2026

Damaging storms are pounding New Zealand every eight days, some lifting roofs, triggering slips, and flooding homes and streets.

This is the first of a new fortnightly series of articles explaining the weather, by senior science writer Paul Gorman.

EXPLAINER: Is it weather or climate, or both?

Getting your head around the difference between “weather” and “climate” is not always easy.

Both are so much in the news these days that, for many people, they have become interchangeable.

But as we’re swamped by anxieties about our changing climate, are we missing important things about the day-to-day weather? Or are we too fixated on each individual storm to be giving proper consideration to the longer-term trend?

Is it a case of “can’t see the climate for the weather”, or vice versa?

For those unsure what is weather and what is climate, there are a number of definitions out there.

It mostly comes down to matters of space and time. Climate is the big picture, often defined something along the lines of “a long-term statistical description of weather patterns in a specific region or globally over a standard period of 30 years”.

A slip covers State Highway 67 near Granity after heavy rain on the West Coast last month.

That means it confines itself to averages of temperature, rainfall, wind and the like, the amount of variation in those, and the frequency of severe weather events.

Weather, however, is what you see out the window or conditions which your senses experience – an icy thundercloud heading your way, trees bending in the wind, rain pouring down, a thermometer rising on a hot day. Weather often only lasts from a matter of minutes to perhaps a few days at most.

You cannot see “climate” as such, because it is unfolding across a much longer time frame.

But that doesn’t mean you can’t see or experience its effects – a rising snowline, different types of plants and pests colonising a new area, areas along a river or the coast which are frequently flooded.

The best definition of the difference is the old chestnut of “weather is what you get, climate is what you expect”.

The Hikuwai Bridge linking Tokomaru Bay with Gisborne was severed during Cyclone Gabrielle. Extremes of weather are becoming more common in many places.

Agencies like the World Meteorological Organization and Nasa often use this to get cut-through with the public. In 1887, Mark Twain said something similar: “Climate lasts all the time and weather only a few days.”

So why do people get confused? It’s largely because the two are inextricably linked and both feed changes in the other – a change in weather patterns, if long enough, ultimately affects the climate, while a changing climate also changes the frequency and severity of certain types of weather.

There’s another great analogy, attributed to Australian scientist Neville Nicholls among others: Imagine someone walking their dog – the person, on a steady path, is like the climate, while the dog, careening around, jumping up and down but roughly following their human, represents the weather.

Some of the confusion around what is weather or climate comes from the longer-term atmospheric circulations we hear so much about, especially El Nino and its opposite La Nina.

These slot in the middle somewhere – they last longer than the weather, from just a few months to perhaps a year or more at most, but still on a much shorter time frame than climate.

Humans, with their usual mixture of impatience and forgetfulness, can easily get the impression these mid-length circulations are changes in long-term climate. A long El Nino can certainly make those in drought-prone eastern parts of the country, or on the wet western coasts, feel like it’s all due to climate change.

Just recently Phil Gibson, boss of insurer IAG,shocked many when he said in the past year we had experienced a major storm every eight days, on average, up from one every 19 days previously.

There is no doubt climate change is altering New Zealand’s weather patterns at what seems like an accelerating rate.

But sometimes some downpours, gales or snowstorms are just due to the whims of the weather, even if climate change is the malign force somewhere in the background guiding them.