The day had dawned blue and clear in the village of Stok in the Indian Himalayan region of Ladakh. Cows ambled along the mountain passes, motor scooters zipped across town and village children worked on a trash cleanup project. But around 6:30 p.m. on Aug. 5, 2010, the sky turned ominously black. “It turned a really funky dark color that I myself hadn’t seen before,” said Lisa Yangchen Blake, an American who moved to the region to become a Buddhist nun.

The winds picked up, and rain started falling horizontally and diagonally. Blake hopped onto a roof to take pictures, and when she looked across the valley, it was “almost like the clouds were trying to turn into a tornado.” Amid the lightning and the thunder, her friends begged her to come down. “It was like, no, no. Something weird is happening. I want to make sure I document it.”

Four and a half hours later, just across the Indus River from Stok, Tashi Chotak returned to his guesthouse in Phyang, a village 12 miles outside of Leh, Ladakh’s main city. The trekking company owner had been at a wedding party and returned home later than usual. Rain fell intermittently as he headed to bed.

Tashi had been asleep about an hour when he was jarred awake by the sounds of a massive storm, “all rain and thunder and lightning in the wind.” He rushed outside with an umbrella, but it was immediately crushed in the downpour. “It was like a waterfall,” he said. A boulder — Tashi estimates it at about 200 pounds — came crashing down the hillside, smashing into a room where his uncle was sleeping. The initial thought of saving the essentials was abandoned; the only goal became getting to high ground. It took Tashi, and his pregnant wife, Cristina, half an hour to cross a tenth of a mile because they kept sinking thigh-high into the mud.

Storms of a certain type aren’t unusual in the region in August. It’s the traditional time of the sky dragon, of thunder and of lightning. The storms roll across Ladakh, providing a cacophonous spectacle but typically little rain. Ladakh’s Leh district normally sees only about 3.5 inches of rainfall a year. In the past, talk of moisture in the Himalayas has focused on its dwindling glaciers and the worry that there’s too little water, not too much. That’s visible from above: The mountains are an undulating expanse of brown, punctuated by blue-white glacial caps and ribbons of green — trees and other plants springing to life along the shores of glacier-fed rivers and streams. But locals say the summer rains have become more powerful since 2004. That’s a problem in a region that’s ill-equipped to deal with massive rains, both on a local infrastructure level and when it comes to national forecasts that could help people prepare and protect themselves.

And in 2010, the rains turned the storm season into a thing to be feared. Aug. 5, when Tashi and Cristina fled for their lives, brought the third straight night of intense rain in the region.

Scientists would link Ladakh’s catastrophic flood to a historic heat wave that killed tens of thousands of people in Russia, 2,200 miles away. For weeks, Russia had been experiencing a heat wave that brought the highest temperatures the nation had seen since record keeping began in 1879. Moscow, where high temperatures in during its warmest months of July and August are typically around 73 degrees Fahrenheit, hit 100 degrees; the Siberian city of Omsk hit at least 96.6 degrees — its average high in August is 72. With the heat wave came drought and nearly 600 wildfires across 480,000 acres. The country, known for its blistering winter cold, was boiling that summer. Russia hadn’t seen anything like it in at least 1,000 years, the head of the Russian Meteorological Center said at the time. When it was over, an estimated 55,000 people were dead, killed either by heat stroke or from conditions such as heart and asthma attacks made more likely by the heat.

Kristen Rasmussen, an assistant professor of atmospheric sciences at Colorado State University, helped make the connection between Russia’s heat wave and Ladakh’s rains. By collecting data from a NASA satellite called the Tropical Rainfall Measuring Mission, “we were able to see what kinds of storms and what kinds of systems we typically expect in the climatology,” she said. The satellite also lets scientists see when weather patterns are atypical, so they can better examine them. And the 2010 Ladakhi rains were atypical.

What Rasmussen found is that Russia’s heat wave was caused by big synoptic waves in the atmosphere — we usually see them as curved lines of red and blue on weather maps that show air pressure, temperature and wind direction — that atmospheric scientists call blocking, because they stay fixed in place for days or even weeks. That blocking had a ripple effect on other weather systems. To understand, it helps to think of our atmosphere as a highway system and weather as the cars that traverse its roadways. A blocking pattern acts like a traffic jam encouraging drivers — in this case, the weather systems — to take alternate routes. In summer 2010, that meant dumping intense rain first on Pakistan, which also suffered devastating floods, and then India, where the blocking pattern pushed up the mountain the monsoon rains that usually fell at lower elevations. In other words, it’s not simply that Russia was hot but that the timing of Russia’s heat wave coincided with the monsoon rains that caused the devastation.

The storms that hit Ladakh are called mesoscale convective systems. They’re complex thunderstorms that are larger and wetter than your typical thunderstorm. And the environment isn’t prepared for all that water. Because the area is usually so dry — visitors are encouraged to drink a minimum of three liters of water a day to stave off dehydration — the soil can hold less moisture than in other places. The reason dry soil holds less water is simple: Moist soil is like a net that catches water, whereas in dry soil, that structure breaks down, and the water passes straight through. Many of us have seen this effect in houseplants that we’ve forgotten to water, where more water seems to pass through the pot than stays in it.

“So when the third system came over on the third night,” Rasmussen said, “the soil couldn’t absorb anything. It was already saturated, and that’s when the flash flood really became a problem.”

In pockets all over the region the rain came, not in buckets or sheets but in cataclysmic waves called a cloudburst. Fourteen inches of rain fell in two hours. Streams overran their banks, and houses were sheared from their foundations, taking sleeping inhabitants with them.

The next morning in Leh, survivors pulled bodies from the muck and laid them out, Muslim alongside Buddhist alongside Hindu, on the stone floor of the old marketplace, beneath the billowing Buddhist prayers flags and in the shadow of the Jama Masjid mosque. It was the only space big enough to accommodate the dead, which totaled more than 200.

In Phyang, home to Tashi and Cristina, “We had eight deaths, among them one family with two small children,” said Cristina, who before moving to Ladakh spent years doing disaster relief with the Red Cross. Tashi’s uncle, who was in his room when the house was crushed by a boulder, was among the dead. Cristina and Tashi also lost their house. A pregnant Cristina and her husband were forced to hunker down in its skeletal remains that winter, when temperatures in Phyang reach -22 degrees F. “I did not know if the baby will stay or if I will lose the baby. It was a big pressure for everybody,” Cristina said. She gave birth to a healthy boy that February.

The deaths, while tragic, may seem less striking when viewed alongside the thousands of lives lost in Russia. But the Russian heat wave, while unusual, was not wholly unexpected. In 2003, for example, heat waves swept across Europe, killing an estimated 70,000 people. Fifteen of the 17 hottest years on record have come after 2000. As the globe gets hotter, we expect more heat waves. But what happened in India in 2010 was unexpected and is less well understood, raising the question of what other unforeseen catastrophes may lay ahead.

More than six years later, one of the lingering questions is: Why wasn’t anyone warned, especially about the heaviest part of the storm? That’s partly because of a lack of good data. “The cloudburst itself is a phenomenon that’s not well understood,” said Ashrit Raghavendra, a scientist with the Indian National Centre for Medium Range Weather Forecasting. The center is responsible for weather predictions up to 10 days out. Because cloudbursts frequently occur in mountainous locations, where there are few weather-monitoring stations, they’re rarely accurately observed, Raghavendra said. Scientists mostly learn about the storms either through word of mouth or through local media reports, which tend to associate any heavy rains with cloudbursts. The definition varies by region, but a 2010 report by the India Meteorological Department considers it a cloudburst when roughly 4 inches of rain an hour falls in a limited area. In Leh, even as much of the town drowned, the airport’s weather station — the only public station in the region — reported a scant half-inch of rain. Before 2010, the most rain ever recorded in the region in a 24-hour period fell in 1933: 2 inches (though, as noted, record keeping in the region isn’t wholly reliable). But many Ladakhi whose agriculture- or trekking-based livelihoods are intimately tied up with the weather say that the summers are getting wetter.

Raghavendra said that prediction of such phenomena just isn’t possible right now; the technology is limited to carrying out after-the-fact investigations. The meteorologists can know what’s happened but not yet tell residents when these bursts will happen again. And he said India currently depends on Earth-observing satellite data from the U.S. to understand that much.

In 2015, in the face of increasing flood events not just in Ladakh but also in nearby Kashmir, the government announced that it had launched the Himalayan Meteorology Programme. The goal is both to improve short-range forecasting and to better predict severe weather events up to 72 hours in advance. In the meantime, scientists and locals wonder why storms seem to be getting more severe.

The challenge is that this region has not had a history of formal, accurate data collection — the type of data that scientists rely on to assess whether changes are happening and, if they are, why. Geologic and plant data can provide some insight into the past, but meteorological models, Raghavendra said, are generally refined through recorded direct observations, which have been scarce. Mostly what we have to go on are the stories told by the Ladakhi people, who have lived in the region for more than 1,000 years. Studies on the region since the 2010 floods often begin by referencing the paucity of available research. Before 2010, not many people were looking, a story that is increasingly common across the globe as people in far-flung corners experience changes in their weather. It’s why scientists are trying to find ways of connecting indigenous knowledge with our understanding of environmental change. Still, it’s tempting to jump to conclusions and say that the 2010 floods — and milder, but still severe, floods that followed in 2011 — were linked to climate change.

Rasmussen, however, is hesitant to say that, because “we haven’t looked at enough years of data to say whether or not there are changes due to climate changes.” She said that scientists prefer to have at least 30 years of data, and that just isn’t available for the region.

But a separate study in 2012 focusing on the Russian heat waves found that although climate change didn’t make the heat wave significantly bigger or hotter, it made a heat wave of that severity three times more likely. The naturalist John Muir once wrote that “when we try to pick out anything by itself, we find it hitched to everything else in the universe.” Although not definitive, there’s a gossamer thread connecting Ladakh’s devastation to the Russian heat waves, and the Russian heat waves to what humans are doing to the climate.

Still, there’s a feeling of pragmatism that, whatever the cause, the Ladakhi will find a way to adapt — this is a culture that has developed over 2,300 years. The behaviors of the Ladakhi themselves, however, may have made the storm more devastating; in recent years, some have built homes in high-risk locations. “I’ve noticed,” Cristina said, “people are building on land which is really not safe, like on the mouth of the river. If there’s another big flood, they’ll really have a problem.”

Reporting for this story was made possible by a fellowship from the International Center for Journalists.