Autumn is definitely here. Big beefy cumulus clouds are scudding across the sky, leaves are flying through the air and on Tuesday a tornado ripped through Hampshire.

The season is summed up by an old proverb about November: “Let the thresher take his flayle, and the ship no more sayle.” In the days of sailing ships, this was the time of year when merchant shipping and the Royal Navy came home to safe harbours for the winter out of harm’s way as gales raged on the high seas.

November has a windy reputation because cold polar air collides with warm air from the tropics and the seas, which are still warm after soaking up the summer’s heat. That clash of the air masses sets off a titanic battle, driving a furious band of wind a few miles high in the atmosphere — the jet stream.

The bigger the contrast in temperature between the cold and warm air, the more furious the jet-stream winds blow. And a fast jet stream helps to spawn and drive storms eastwards across the Atlantic.

At present the UK is in the firing line of the jet stream, which is why the wind, rain and clouds are sweeping through the country so fast this week. It looks as if there could be some wet and blowy conditions for weekend bonfires and fireworks, and it stays much the same for the rest of November — typical autumn weather. But at least the rain is good news for wild fungi, which are thriving after the dry September and October.