# eli5 Why can data models predict the future climate but not the weather?

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Why can data models predict the future climate but not the weather?
Why are weather forecasts often wrong but modelling of the future climate highly accurate? I would presume a more complex system over a longer period would be harder to predict.

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Who said their climate prediction are highly accurate? And weather prediction is pretty damn accurate. But it’s kinda like sports. I can predict the top teams each year with pretty good accuracy. But I can’t mail down how my hits one player will get in one specific game

> I would presume a more complex system over a longer period would be harder to predict.

You are not wrong, and in part you are onto why it’s harder to predict the weather.

**Weather** is what conditions of the atmosphere are over a short period of time. **Climate** is how the atmosphere “behaves” over relatively long periods of time.

You can think of weather as the very specific details, and Climate as the broad average.

So is it going to rain tomorrow in my town for 30 minutes, is much harder than saying rain is likely in the next month, or the average temperature will rise by 2 degrees.

Hope that makes sense

Let’s make an analog.
You are able to save on average 2000 a month. That means in 10 years you should have 240.000 on your bankaccount.

This doesn’t mean you will be saving 2k each month. Some months it is 500 and others it is 3k.

In other words we see a trendline which should mean x to the weather. But that doesn’t corrolate directly for the weather we will be having on a daily basis.

I think the predictions people are looking for regarding weather are far more precise.

For example the prediction about climate that comes to my mind is “the average temperature of earth will rise”.
(Stuff like a rising water level are direct conclusions of this one very vague prediction.

But if you are talking about weather you want to know what will the temperature be next Tuesday at exactly 4 pm in this very specific city.

Another thing to keep in my mind with weather you get a new chance to check the predictions everyday.
While with climate it needs a few years to get an answer.

Because complex systems regress towards a median, in accordance with a model’s predictions, especially over long intervals, whereas short-term predictions are subject to greater volatility. In other words, it’s much easier to say that 1,000 cars will go down the road, than it is to say that car X will take the next off-ramp.