Climbing Everest is always dangerous, but expedition organizers have warned that a combination of extreme weather, unsafe shortcuts and "impatient" foreign climbers has resulted in one of the deadliest mountaineering seasons.

While the last search and rescue teams have disbanded, climbing experts say few of the 17 people who have died or are missing or presumed dead this season could have been averted.

"This season in general has been very bad," said expedition organizer Mingma Gyalye Sherpa, whose team was responsible for opening the route to the summit. "The main reason is that the weather was extremely cold, but there was also carelessness," he added.

More deaths have been reported in past seasons, but those numbers include a few deaths in individual large-scale disasters. In 2014, an avalanche killed 16 Nepalese guides, and the climb was suspended after that.

The deadliest season was 2015, when at least 18 people died in the mountains in an earthquake that killed nearly 9.000 people across Nepal. This season, 12 people died, and five are missing.

Ten of them were foreigners, which is the highest recorded number of such victims, as well as seven Nepalis: guides, workers and one climber. About five climbers die each year on oxygen-deficient routes to the 8.849-meter-high ice peak.

Nepal has issued a record 478 permits to foreign clients this season, with around 600 climbers and guides reaching the summit, leading some to suggest the number should be reduced.