The heaviest snow in two decades blanketed Lesotho in late July 2016. The storm prompted the airlifts of at least eight tourists, and caused the deaths of several shepherds in the Joe Gqabi District Municipality, according to news reports.

It was the most snow the area has received since 1996, said Stefan Grab, a professor at the University of the Witwatersrand (South Africa). Twenty years ago, the snow would have lasted as long as a week in places. This year, he said, snow at altitudes at or below 1800 meters (roughly 5,900 feet) melted within a day or two.

“This particular snowfall was an extreme event, but it’s only extreme in the context that we haven’t had something like this in a long time," said Grab. "In the first half of the 20th century, or certainly in the 19th century, these were very common.”

Lesotho’s winters tend to be short, usually beginning in June and ending in early August. The hilly, landlocked kingdom, surrounded on all sides by South Africa, is comparable to Maryland in size. For most of the year, the mountains are full of green grass, thatch-roofed huts, and shepherds grazing their flocks. Permanent pastures account for more than 65 percent of Lesotho’s agricultural land. Hot summers bring plentiful rain, while winters are cold and typically dry. The landscape turns yellow around May, with prickly, parched grass and areas of burnt vegetation.

The Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite captured the top image of heavy snow on July 27, 2016. The second image, taken on August 2, 2016, shows the mountains after several days of melting.

The nation experienced much heavier snowfalls in the 1830s and 1840s, according to a paper in Climate Dynamics. Severe winters in past centuries meant shepherds would move their flocks to the highlands in the hot months and bring the sheep back down to the lowlands in the winter. But that has changed in the past few decades, Grab said. Milder winters mean many shepherds leave their flocks in the highlands year-round. As result, a severe storm like the one in July 2016 has greater potential to kill sheep and shepherds.

“If you are a herd boy who was born sometime since 1996, you would not have encountered such an extreme snowfall,” said Grab. “You wouldn’t be accustomed to it or prepared.”

Though there are now fewer extreme snow events, mild snows have been frequent in recent years. “For the most part, they are very light snowfalls, mostly just a sugarcoating over the landscape,” said Grab. Still, he said, it’s possible that the uptick in these milder snow events can be attributed to better record-keeping. Whereas in the past, newspapers may not have noted a bit of powder, now satellite imagery is able to detect even a fine dusting of snow.

NASA image by Jeff Schmaltz, LANCE/EOSDIS Rapid Response. Caption by Pola Lem.