Secrets of the season: The Independent's new weather columnist Liz Bentley explains the mysteries of autumn

Forget mists and mellow fruitfulness. This week has seen snow, sun and frost across the UK.

Many of us will have had a taste of winter weather over the last few days, with shivering temperatures, dank fogs and strong gusts, as northerly winds brought cold air in from the Arctic. And while we often think of autumn as the season of mist and mellow weather, it's more complicated than that – two weeks ago we were celebrating a sizzling Indian summer, and next week we'll be reaching for our umbrellas.

Autumn is a transition season between summer and winter, with hot and cold doses of both thrown into the mix – and it all comes down to wind direction. If we get a southerly flow we bask in the warm temperatures from the Continent (where cities like Rome and Athens are still enjoying temperatures in the mid-twenties), but if we are on the receiving end of a northerly flow, as we are now (caused by high pressure out in the Atlantic and low pressure over Scandinavia), we suffer cold temperatures and hard frosts.

That's why yesterday morning many people awoke to a sharp frost and biting winds, but by tomorrow we'll be suffering a typically seasonal experience of mild and damp conditions as wind conditions change and a westerly flow brings rain for the weekend. This isn't unusual for this time of year, which tends to be very changeable.

Looking towards winter, it's almost impossible to predict what's in store from today's weather, but we can look at annual forecasts that concentrate on sea temperatures across the globe, and it's not good news.

Meteorologists in Russia have noticed an anomaly in the Gulf Stream, the ocean current that brings warmer sea surface temperatures and keeps the water around our shores relatively warm. Vadim Zavodchenkov, a leading specialist, has predicted that this anomaly will have an impact on the winter not only in Russia but across north-west Europe: because of a drop in the warming currents of the Gulf Stream, we should expect one of the coldest winters for 1,000 years.

So if you thought last winter was a shock to the system, then you ain't seen nothing yet.

Dr Liz Bentley is The Independent's new weather columnist and the founder of the Royal Meteorological Society's theWeather Club (www.theweatherclub.org.uk). Her first column will appear on Tuesday