After the torrential rain of Bank Holiday Monday, Britain is in for another shock with a ‘polar plume’ arriving to bring in a week-long chill.
The Met Office said drier, polar air would chill Britain from Wednesday (September 2) until Sunday (September 6), with below-average 11-18C days feeling like 9-15C for most in windchill.
Night time temperatures could drop as low as 0C, bringing a chance of frost.
Met Office forecaster Alex Burkill said: “Northerly air means cool temperatures - and possible gales in the East will make it feel even cooler.”
Forecaster Brian Gaze of The Weather Outlook, also confirmed the cold weather, adding: “A ‘polar plume’ means very chilly nights and ground frosts are possible, with a chance of 0C in sheltered parts of northern England and Scotland by the weekend.”
And Leon Brown of the Weather Channel said: "A cold front looks like moving south on Saturday (September 5) with clearer weather following, but may bring a very chilly start to Sunday with ground frosts and possibly temperatures down to 0C in sheltered parts of Scotland and N.England."
El Nino to warm up autumn
But it's not all bad news - an Indian Summer is due in autumn as the Met Office forecasts hotter-than-normal temperatures over the next three months.
Forecasters said the probability of much warmer than usual conditions over the next three months was almost twice as high as usual - at up to 35% versus the usual 20%.
Highs up to 29C could be seen as warm September spells have hit 29C in four of the past six years.
The Met Office said warmer-than-normal conditions are expected later in autumn due to the effects of El Nino - the warming of the eastern Pacific Ocean which affects the world’s weather - arriving in Britain.
The forecast comes days after the Met Office predicted a sunny Bank Holiday days before Monday's 20-hour washout.
The error went some of the way towards justifying the BBC's controversial decision to scrap its £32.5m annual contract with the organisation and find another forecaster.
Daytrippers cursed forecasters, with Mandi Riseman tweeting a Met Office rainfall map and saying: “Happy Bank Holiday everybody - bloomin’ rain.”
Met Office forecaster Alex Burkill said: “We were optimistic a system would move through on Sunday - but it slowed down and unfortunately affected Bank Holiday.”
The Met Office also bungled by forecasting a hot, dry summer at the start of June despite the fact it was one of the coldest and wettest for 27 years.
Its most notable blunder was the "barbecue summer" forecast in 2009, which preceded a washout and led the organisation to stop producing long-term outlooks.
