How do people know what the weather is? – Liam, age 5.
That’s the job of meteorologists. They’re not experts on meteors, they’re experts on the weather!
The name meteorologist comes from a very, very old Greek word, which means “studying things that are high in the air”.
They use three main things to help them decide what weather is on the way: weather observations, computer weather models, and their own experience.
That means what the weather is doing now. So they need lots of measurements of things like air pressure, temperature and rainfall, not just from on the ground, but high in the sky and even from up in space as well. For those measurements, they rely on weather balloons and airplanes, as well as radars and satellites.
Computer weather models
Really powerful computers use information about what the weather is doing now and how it has behaved in the past to help predict how it will behave in the future. They do lots and lots of calculations to tell us what is most likely to happen.
The final thing meteorologists need is their own experience. That helps them decide whether the computer’s prediction is likely to be right, or perhaps needs to be changed a little bit. Usually, the meteorologists have spent a long time studying the weather so they have a really good knowledge of how it behaves.
Twice every day the Bureau of Meteorology (which is sometimes called the Weather Bureau) sends out the official weather forecasts for towns and cities across Australia.
These forecasts look at only the next seven days because the further ahead they try to predict the harder it is to get it right. That also means the forecast for tomorrow or the day after is likely to be more accurate than the one for this time next week.
You should also remember that sometimes the weather is very local. That means it can be raining in one place but dry and sunny just a few kilometres away. So next time you see a forecast for a “shower or two” but you see mostly blue sky where you are, give your friend on the other side of town a call. They might be wearing a raincoat and hiding under an umbrella!
So, we don’t always know exactly what the weather is going to be like at your place, but thanks to the Bureau of Meteorology we can give you a very good idea of what to expect.