Why are all my weather apps different?

Forecasting is more accurate than ever, but mobile apps can still disagree wildly. What causes the difference - and which one is best?

It was a tale of two storms. The first consisted of the rain and thunder forecast for Bournemouth by the BBC weather app on the Saturday spring bank holiday. The second came when the first failed to materialise and a tourism manager in the town complained that visitors who stayed away could have come after all and enjoyed sunshine and blue skies.

This opportunity to rage at inaccurate forecasting, bash the BBC and highlight the grievances of small businesses did not go to waste. For the Sun, it was a "blunderstorm". The Mail gave voice to furious social media users whose weekend had been ruined by "crap forecasting" and "total incompetence". The Spectator even managed to use the row to take pot shots at climate-change predictions.