Rain, rain, rain: Just why is it so wet this year? When on earth is it going to stop?

Watery facts of Summer '93

Britain's wettest September since 1976.

Second wet summer in a row. After last year, it was the wettest summer for 25 years.

Floods this year in the United States, Bangladesh, India, Nepal, New Zealand, Australia, north Africa, South Africa, China, Japan, Venezuela, France, Germany, Italy, Switzerland.

In 24 hours from Friday morning, Gatwick had more rain than it usually gets in a month.

Floods yesterday in parts of Surrey. Yorkshire and London also saw floods this summer.

Reservoirs are 30 per cent fuller than in 1990.

It rained on St Swithin's Day, traditional herald of a wet summer.

Forecast: today, dry at first, rain later. For the week: rain.

DOWN and down it has come, drowning the fetes and wedding receptions, soaking the sports days and football matches, trapping children indoors, drenching washing on the line and turning every journey into a miserable, chilly douche.

It finds the broken tiles in the roof and the hole in your shoe; it trickles down the back of your neck and through the car window that has been left slightly open; it swills in gutters clogged with leaves and leaps up at you as the bus goes past. Whether you linger or make a dash, it drowns you. It is rain - torrential, sloshing British rain.

By any measure we are having a very wet time. Rainfall for England and Wales last month was 44 per cent up on average. For East Anglia, a notoriously dry region, it was 72 per cent above normal. The London Weather Centre confirmed yesterday that it was the wettest September since 1976.

In fact, according to the Institute of Hydrology in Wallingford, for most of us it has been the wettest summer since . . . last summer. Terry Marsh, who looks after the national water archives there, says: 'The summer half-year from April to September has been unusually unsettled. With the exception of last year, it was the wettest April to September period for 25 years in parts of the English lowlands.'

Yes, we have had two in a row. What price now Mr Marsh's ''hydrologically stressed' (dry) summers of 1989 and 1990? Gone are the dry rivers and reservoirs, the hose-pipe and car-wash bans. They are history, swept away by the relentless months of inundation.

Somerset Maugham had the words for it: 'It was unmerciful and somehow terrible; you felt in it the malignancy of the primitive powers of nature. It did not pour, it flowed. It was like a deluge from heaven . . . It seemed to have a fury of its own. And sometimes you felt that you must scream if it did not stop, and then suddenly you felt powerless, as though your bones had suddenly become soft; and you were miserable and hopeless.'

It is not just Britain. It has been raining in Italy, where storms swept across the Ligurian coast, killing six. It has been raining in France, Germany and Switzerland. Torrential rain hit Japan in August and the American Midwest in July, causing floods of biblical proportions when the Mississippi burst its banks. And yesterday, in the Indian state of Maharashtra, scene of last week's earthquake, heavy rain was disrupting the rescue work.

What is going on? Could these events be somehow related? If you subscribe to chaos theory, the branch of mathematics that attempts to make sense of the unpredictable, you might believe they are. Chaos theory tells us that a single flap of a butterfly's wing in Australia can cause the necessary air turbulence to trigger a thunderstorm in Teddington. Causes may be so remote and apparently insignificant that they are probably beyond our comprehension.

Chaos theory, however, does not cut much ice in the saloon bar. There, conversation often blames our weather woes on Mount Pinatubo, the volcano in the Philippines that erupted in 1991. It certainly caused extensive climatic disturbances, but according to Professor Brian Hoskins, a meteorologist at Reading University, its effects should by now have died off. Likewise, El Nino, the warm Pacific current that occasionally provokes monsoons and storms by flowing in the wrong direction, is unlikely to be to blame this time, he says.

And the storms over the American Midwest? Could they be responsible? 'There are connections across the globe,' says Professor Trevor Davies, director of climate research at the University of East Anglia. 'We can't look at chunks of the atmosphere in isolation. But you can't make a direct connection, saying that if it's wet in north America it's going to be wet here.' So what do we know? Britain, being surrounded by water, has a maritime climate. If there is wind, it has come over the sea. At this time of year the sea is relatively warm, which means that there is more moisture in the air above it, and this is carried in by the winds. When these moving air masses reach land they rise and cool quickly. The result is condensation - and rain.

This happens every summer. Why it should have rained so much this summer is less easily explained. Normally, after one wet air mass has dumped its load and passed on, there is an opportunity for high pressure to build up. This warms things up and, for a while, repels further threatening wet masses. This year, in simple terms, the high pressure has usually been somewhere else, so wave after wave of moisture-laden air has washed over us. (Greece, meanwhile, has been basking in sunshine. As Professor Hoskins puts it, 'One person's bad weather is another person's good weather'.)

It has also been cooler than usual. This is because there has been a tendency towards higher than normal pressure over the Arctic and Greenland, and lower than normal pressure over northern Russia and Scandinavia. Taken together, this has led to frequent streams of cool, northerly winds over Britain.

If all this seems unsatisfactory, it is no accident. Meteorologists are reluctant to admit what the wet pedestrian feels in his bones: that there has been a pattern to this summer's weather.

They insist, for example, that August was a relatively dry month. Tim Palmer, at the European Centre for Medium Range Weather Forecasts in Reading, offers an explanation that is not an explanation: 'I think what we're seeing is just a manifestation of the chaotic nature of the atmosphere.'

In much of the world, of course, they are delighted when it rains, and there was a time when they would do almost anything to make it do so. In The Golden Bough, J G Frazer's classic survey of ritual and superstition published 70 years ago, he wrote at length about rain-dances, rain-songs and rain-birds, all thought capable of bringing showers to water the crops and fill the wells.

It may be a measure of the distance that now removes us from nature that we should have come to resent rain so much. For all its life- giving powers, it has become nothing but a nuisance to urban man, who gropes around for someone to blame - the Meteorological Office has received a steady stream of complaints this summer. But this year even rural man is unhappy. Farmers need rain, but not in these quantities or at this time of year. It causes fungal diseases and moulds, spoils fruit, flattens wheat and makes harvesting a nightmare.

Can we do anything about it? J G Frazer also wrote of societies where rain was abundant and rites were performed to prevent it. In the north Indian region of Kumaon, for example, 'a way of stopping rain is to pour hot oil in the left ear of a dog. The animal howls with pain, his howls are heard by Indra, and out of pity for the animal's suffering the god stops the rain'.

Science has taught us that we cannot comprehend the weather, or control it. We can conquer distance and disease, shatter atoms and tinker with genes, but we cannot stop the rain. Even the Russians, with their famous cloud-seeding techniques, could not save Michael Jackson's Moscow concert from a wash-out last month.

This powerlessness contributes to our frustration, but there are also clinical reasons to feel miserable. Doctors now recognise a condition known as Seasonal Affective Disorder (SAD), a depressive illness associated with abnormal sleep patterns. It is believed to result from irregular production of the hormone melatonin, which is controlled by the amount of light entering the eyes. Usually it occurs in winter, when the days are short and often cloudy, but this summer has given it an excuse to strike early: the number of sunshine hours in September was about half the average for the month.

It can hit us in our pocket, as well as our health. The farmers are a case in point, as are the builders, whose sites come to resemble the Western Front. Insurers don't like it either - roofs leak, there are floods and there are more accidents.

Some industries are surprisingly resilient. Incoming tourism, for example, has been largely unaffected, because, as the English Tourist Board says, 'Overseas visitors certainly don't come to England for the weather'. But rain does send British holiday-makers in the other direction. With the modern trend towards late booking, people can have a taste of the British summer before they make their choice between Torbay and Mykonos; this year it was no contest.

And then there are our water companies, as usual on the wrong side of public opinion. 'We're very pleased,' says Thames Water. 'We like this sort of prolonged period of rain. We're miserable buggers really.' Umbrella sales are up. T Fox and Co of Threadneedle Street, retailers to the City gent, report a doubling of sales, many of their products doubtless finding their way to the British Rail lost property department at Charing Cross, where takings have also doubled.

The ducks, famously, like it. Not because they enjoy being rained on, but because it releases seeds from the grass for them to eat. And then there are the slugs and snails, which suffered badly in the recent dry summers. Watch them now, slipping in their hundreds across the wet, unmown lawns of Britain, having the time of their lives.

What everyone wants to know, however, is when it will stop. Dave Cullum at the Met Office can't tell you. 'There is not a soul on earth who knows. It could change in a week. It is possible to end up with a warm, dry October . . . but there is no sign of it yet.'

(Photograph omitted)