Michael Williams: Readers' Editor

If it rains today, please don't blame our weather forecast
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Something on your mind this morning? It's likely to be the same thing that's bugging me and 50 million others. We're all desperately hoping to squeeze a few hours of sunshine this Bank Holiday from this most miserable of summers. Only a few days of the season left, and it'll almost certainly go down as the wettest on record.

Reader Robert Lewis from Maiden Newton in Dorset, is fretting about the forecast. "What's happening to the accuracy of your forecast, which always seems to offer a bleaker outlook than reality?" he writes. "Often you are forecasting rain or showers for the South-west, when some of us have had quite decent weather here. Who provides your information? A soothsayer who studies the migration of frogs?"

Hardly, Mr Lewis. The 'IoS' weather is supplied via the Press Association from the Meteorological Office, which is the main source for weather forecasts in the UK. But you're not the only one worrying. Councillor Maxine Callow, Blackpool's tourism boss, claimed last week that inaccurate weather reports are driving visitors away from the nation's most popular seaside resort. She compared Met Office reports in July with the actual weather and found they often failed to tally. "This isn't about sour grapes or wanting to fabricate reports in our favour. It's about simply giving people an accurate overview," she said.

Certainly, there's a widely held suspicion – since the fiasco of 1987 when forecaster Michael Fish failed to predict the devastating Great Storm – that Met Office reports have erred deliberately on the pessimistic side to avoid being wrongfooted again. "Nonsense," said a spokesman when I put it to him. "We're a multimillion-pound business and that would hardly make sense." The problem is that in an age of supercomputers and 24-hour satellite surveillance, there are ever-higher expectations of accuracy. "People have to bear in mind that a forecast is exactly what it is – a forecast. But we are better at forecasting now than at any time in history."

So how accurate is your weather forecast? On maximum and minimum temperatures for the next day in 11 cities across the UK, Met Office predictions are right more than 80 per cent of the time. Rain is more of a problem. The Met Office says: "Unlike temperature, rainfall may, or may not, happen, especially when falling as showers. One side of town may get rain while the other doesn't." So it uses a measure of probability. If one represents total accuracy, then the Met Office scores 0.349. Longer-range forecasts are even less reliable – nine out of 10 five-day forecasts are amended as the day gets closer.

A Stockholm university professor once did tests on a piece of seaweed pinned to the wall of his office. He claimed it correctly predicted the weather 44 per cent of the time.

Our weather forecast is on page 73. Let's hope it's right for you. But try not to shoot the messenger. Robert FitzRoy, the founding father of the Met Office, was a keen amateur forecaster. But instead of hailing his predictions as the beginning of a new science, he was ridiculed by journalists whenever he got it wrong. Depression set in, and one Sunday morning in 1865 cut his throat in despair.

Have a nice day – and don't forget to take a mac.

Email: readerseditor@independent.co.uk