Heavy footfalls are expected on Mount Everest this spring, as a record 374 fee-paying climbers—12 of them Nepalis—have been cleared to scale the world’s highest peak. And given the erratic weather pattern this season, many climbers are concerned that they could be left with a small window to make it to the top, and face a traffic jam during the final days of ascent.

The 2017 Everest climbing season ended with a mix of triumphs and tragedies: deaths, injuries, record crowds, frauds and other controversies. That was last year.