What does '30% chance of rain' mean? Expert on TikTok claim

Penny Burfitt and Gillian Wolski
·2-min read

Everyone was left mind blown and a little confused this week after a TikTok user, Gogglebox star Scarlett Moffat, went viral with her claim that we've all been reading popular weather apps wrong.

In the explosive video, the star explains that for years she had misunderstood the percentages on the weather app, saying that where she thought '30% chance of rain' meant there was a 30% chance it would rain at any particular time, it, in fact, meant 30% of a given area would be covered in rain.

Using a weather forecast app on cell phone.
What exactly is your weather app telling you? Photo: Getty Images

"It doesn't mean that it means that 30% of your area will be covered in rain," she explained in the video which has racked up over 2.5 million views and hundreds of thousands of likes and comments.

In the video's comments, users were mindblown.

Scarlett Moffat Gogglebox star percentage chance of rain
Gogglebox star Scarlett Moffat made a wild claim that the percentage chance of rain doesn't mean what you think it does. Photo: TikTok

"Omg I thought that too!" one wrote.

"You're joking!!!" another wrote.

She wasn't joking, but it turns out she may as well have been because we have done the meteorological digging and we're ready to bust this myth wide open.

In a highly confusing twist, the misconception is in fact a misconception, the percentage palaver simply much ado about nothing. 

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Experts reveal truth behind TikTok claim

The experts over at the Weatherzone app have weighed in and the verdict is final.

"The claim made on TikTok for the way rainfall forecasts are represented for individual locations on Australian weather apps is incorrect," Weatherzone meteorologist Ben Domensino told Yahoo Lifestyle.

Weather app rain forecast sydney
At least in Australia '30% chance of rain' means exactly what we thought it did all along. Photo: Yahoo Lifestyle

Confused? So were we.

So we asked him, what exactly does this now-mysterious percentage actually mean?

It turns out contrary to Scarlett's claims at least in Australia a percentage chance is exactly what we thought all along.

"The percentage chance of rain that you see in Australian weather apps shows the likelihood of any registrable rain at your location within a given time period," Ben explains. "So if you live in Parramatta and see a 30% chance of rain on the daily forecast, there is a 30% chance that you will see any rain in Parramatta during that 24-hour period."

'Registrable rain' is any rainfall over 0.2mm that can be measured.

"The most likely rainfall amount (e.g. 5-10mm) is given separately to this percentage chance," he continues. "This is how much rain will most likely fall if it does rain."

So there you have it, if this has left you feeling equally confused our professional advise is to always bring an umbrella just in case.

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