The BBC Weather app is too pessimistic in its forecasts, predicting colder and wetter weather than comes to pass, data shows.
It is also less accurate than the Met Office when it comes to forecasting how warm or cold it is outside.
These are the findings from the University of Reading’s Department of Meteorology, which have been shared exclusively with The i Paper.
It builds on academic findings we revealed earlier this year, which showed that weather apps are often wrong and can perform “surprisingly poorly” even in their short-range outlooks for the day ahead.
The British public loves complaining about their weather forecast apps almost as much as the weather itself, with the accuracy of the services sparking ferocious debate.
The University of Reading has now carried out an in-depth comparison of two of the UK’s most popular weather apps to discover which is most accurate.
Meteorology researchers have been examining the forecasts in comparison to the actual weather monitored at the University of Reading Atmospheric Observatory since early October.
The university is launching the ongoing monitoring project online, so users can check which forecast is performing best for themselves.
Rainfall predictions from both BBC Weather and the Met Office have generally been too pessimistic over the last three months, they discovered.
Both apps overestimated the chance of drizzle, showers and downpours – predicting that rain is more likely than not 17 per cent of the time, when it actually rained only 12 per cent of the time.
When it comes to gauging how cold it is outside, the Met Office was found to be more accurate than BBC Weather.
The BBC’s app is slightly too gloomy, forecasting chillier conditions than in reality, the data showed. The Met Office predicted the temperature more accurately on 9.6 per cent more occasions than BBC Weather.
However, the Reading scientists also found that BBC Weather did perform better than the Met Office when it comes to predicting dry spells.
The BBC Weather app was better in anticipating days with no rain. It correctly predicted whether it would rain or not on 9.4 per cent more occasions than the Met Office.
“The Met Office is a little bit better on temperature. The BBC is predicting the temperature very slightly colder [than the Met Office],” said lead researcher Dr Rob Thompson.
“The BBC is a little bit better on rainfall. That’s partly because they are more willing to confidently say they’re very little chance of rain.
“Both of them are a little bit pessimistic when it comes to rain,” he added.
Britain’s tourism chiefs have previously claimed businesses were being damaged by overly-grim weather forecasts which encourage potential visitors to stay indoors.
However, Dr Thompson said erring on the side of negativity helped the public avoid getting caught in bad or even dangerous weather unexpectedly. “A little bit of pessimism is probably a good thing. It helps people prepare,” he said.
A previous University of Reading study done for The i Paper, which ranked five popular weather apps, found BBC Weather to be the least accurate forecaster.
The two-week evaluation found that the Weather Channel performed best overall, with AccuWeather in second place, the Met Office third, Apple Weather fourth and the BBC app ranking bottom.
The latest in-depth research from the University of Reading, which continues to collect hourly data, has analysed more than 54,000 forecasts from both BBC Weather and the Met Office during autumn and early winter so far.
The BBC has previously been criticised for picking too pessimistic an icon to summarise the day’s weather. It means a black cloud symbolising overcast weather can be chosen even if only part of the day is overcast.
The broadcaster has justified its selections as the symbols “most likely to affect the user”.
The corporation also raised eyebrows in 2015 when it dropped its dependence on the Met Office and switched to European firm MeteoGroup to provide its weather information.
Responding to the latest research findings, a BBC spokesperson said: “Predicting weather conditions isn’t a precise science, and our own independent analysis suggests that our forecasts meet and – for some parameters – exceed the industry standard.
“Our research also shows users have a high appreciation of our weather services, but we’re always interested in ways to improve.”
A Met Office spokesperson said the organisation runs tests on the accuracy of its forecasts, as well as an ongoing accuracy survey on its app to monitor “how accurate our forecasts are perceived to be by our users”.
They added: “By monitoring the thousands of responses we get each day, we can identify trends and make improvements to our data feeds and user interface. We’re always looking to improve our forecasts on our app and exploring ways to provide additional weather information.”
