Something extraordinary, even miraculous, is happening in Death Valley, one of the most scorching and forbidding environments on the planet. For decades, the intrepid have had to steel themselves to venture into this most remote corner of the Mojave Desert with their four-wheel-drives and maximum-strength air-conditioning, drawn by the name and the promise of blistering heat at the lowest elevation in the western hemisphere, 282ft below sea level.

Something extraordinary, even miraculous, is happening in Death Valley, one of the most scorching and forbidding environments on the planet. For decades, the intrepid have had to steel themselves to venture into this most remote corner of the Mojave Desert with their four-wheel-drives and maximum-strength air-conditioning, drawn by the name and the promise of blistering heat at the lowest elevation in the western hemisphere, 282ft below sea level.

Now visitors are flocking for a very different reason, a once-in-a-lifetime opportunity to see the salt flats and the forbidding peaks of the Amargosa and Panamint Ranges strewn with fields of riotously colourful wild flowers.

Death Valley is one of those places where rain is supposed to fall sparsely, if at all. Yet, since last summer, hardly a month has passed without a soaking from the heavens, anything from modest downpours to flash floods uprooting roads and buildings. It has been the wettest season since records began in 1911. And, now that the sun has come out again, the valley has exploded in deep golden yellows, purples, blues, reds, greens and whites.

"It's the best in a century," said Vicki Wolfe, one of the rushed - and deliriously happy - team of National Park Rangers stationed in the valley. The last major explosion of wild flowers, during the El Nino-ravaged winter of 1997-98, caused valley habitués to say at the time that they had seen nothing like it in their lives.

But this time is even better, because the rain has been stronger and more regular, and because of the sheer quantity of flowers set beneath the snowcapped highlands of Telescope Peak and the other mountains flanking the valley's western side. The hottest place on earth now looks like a version, albeit fragile, albeit temporary, of Shangri-La.

At the lowest point of all, a spot known as Badwater, a putrid pool of chloride, sulphates and residual spring water has expanded into a full-blown lake stretching several miles. It is not deep enough to swim, but the sunlight now glistens and dances on its rippling waters, and it has even attracted a handful of weekend kayakers.

No longer the Valley of Death, but something approximating its opposite, the landscape is so arresting as to seem almost fake. Squint a little, and parts of it could almost be mistaken for the Scottish Highlands; the rocky hillsides bright green instead of brown or grey, the creosote and mesquite bushes doing a passable impersonation of Hibernian heather, and the scene tinged with the blues and purples of larkspur, purplemat and Mojave aster. Close up, beneath the seas of desert gold sunflowers and poppies, the rugged, stony soil reveals scenes of extraordinary floral delicacy. Wispy purple balls of pollen cling to the stems of Spanish needles and scarlet locoweed. A stunningly beautiful plant called a desert five-spot is made of five perfectly cupped purple flowers cradling regular reddish patches at their base.

The transformation has had a bizarre effect on the animal kingdom. The profusion of flowers and seeds has sparked an explosion in the number of insects, lizards and small rodents and they, in turn, have boosted the food supply of the larger predators, coyotes, foxes, owls and hawks. But the animals are almost completely invisible, at least during the day, when the valley's most visible presence is biggest predator of all, the human being. During the quieter weekdays, homo sapiens reveals itself largely in the form of middle-aged Midwesterners, many of whom heard about the extraordinary goings-on in the valley and jumped on the first available plane to Las Vegas, where the rental companies have been doing a brisk business in four-wheel-drives and recreational vehicles. Their motivation was certainly spurred by the persistence of bitter winter storms in the eastern United States, but they also demonstrate a deep love of nature and a real relish in being able to bring their all-American gadgets and accessories - digital cameras, tripods, binoculars and plentiful reference books on the flora and fauna of the eastern Mojave - and finally put them to proper use.

Kit Howard, a pharmaceutical industry consultant from Michigan, hooked up with her mother, who lives in New Jersey, and together they made the 100-mile drive from the bottom end of the valley to the top as though they were rediscovering their youth, jumping out of the car at regular intervals, reading up on the different floral varieties and basking in the spring sunshine. "We're never going to see this again, so we're making the most of it," Howard said. "As soon as we read about this, we were on the phone making plans to come."

The freak of nature on display in Death Valley reflects the bizarre climatic behaviour across the American West all winter. Since Christmas, the weather in Los Angeles has more closely resembled the steady downpours familiar in Seattle and the Pacific North-west. The canyon roads of the Hollywood Hills have at times resembled rushing streams. The Los Angeles river, usually a trickle confined to a concrete casing, has raged and overflowed. And one coastal community near Santa Barbara was devastated when the hillside behind crumbled and collapsed, crushing several houses.

Death Valley's encounter with extreme weather began much earlier, with a flash flood last August that turned the whole valley into a raging sea of debris mixed with water in only two hours. Hydrologists called it a once-in-a-century, perhaps even a twice-in-a-millennium event.

Parked cars were sent careering into washes. One middle-aged man and his mother were swept away in their car and were found dead, still strapped into their seats, several hundred yards away. Sturdy concrete lavatories buildings were lifted off their moorings and shifted hundreds of feet. Chunks of asphalt were simply popped open on the roads, lifted up and dumped on top of other bits of roadway. Sewage and water systems broke down, and the carefully groomed, springwater-fed lawns of the Furnace Creek resort in the centre of the valley were comprehensively wrecked. "We had this frothy, tumbling mass of debris," Ms Wolfe, the park ranger, said. "Everything turned together like a big, rocky milkshake."

For 10 days the park had to be closed for repairs. The main north-south road running through Badwater was not ready for three weeks, and stayed open for just 10 hours before another storm closed it again. So the pattern was established for the autumn and the winter. Road crews have been working 10 hours a day, six days a week, and still major chunks of the road system are closed.

Christmas week was the wettest week on record in Death Valley, and there was another dramatic downpour three weeks ago, dumping an inch more in a few days. (For comparison, the average annual rainfall in Death Valley is 2in. Some years it does not rain. This year, so far, there have been 6in, and that is only on the valley floor. The rainfall at the tops of the mountains has been many times that, adding to the saturation of the valley.) Under such conditions, it is hard not to recall that just 10,000 years ago Death Valley was a lush landscape of lakes, plant and animal life. Shifting climate patterns changed that, with the mountains keeping rain out and preventing circulation of air in summer, when temperatures hit 50C. The record is 57.2C.

The first white settlers came in the winter of 1849, when gold prospectors hoped to find a shortcut to the mother lode in the Sierra Nevada mountains. They were trapped for a month, and survived only thanks to the natural springs at Furnace Creek. "Goodbye Death Valley", one of them wrote in his diary as they left, and the name stuck. In the 1870s, mining companies hired Chinese labourers to hack borax crystals out of the salt-pan. It must have been punishing work, not least because the borax had to be hauled by wagon for 10 days to the nearest railhead at Mojave, 165 miles to the south-west.

Herbert Hoover established Death Valley as a national park in 1933, and Franklin Roosevelt directed the building of roads and resort facilities as a public works project during the Depression. Geologists love the place because it exposes different periods of geologic time as clearly as anywhere in the US, even the Grand Canyon.

Tourism has been a harder sell, although winter is pleasant and summer attracts the kind of visitor who likes a challenge. Night here is popular, because the stars in this desolate place are plentiful enough to resemble a twinkling soup. And the sand dunes near Stovepipe Wells make for great sledding in the dark.