How cold is Mount Everest?

January is the coldest month and July the warmest, and the gap between them is smaller than people expect. The peak averages around −36 °C (−33 °F) in midwinter and around −19 °C (−2 °F) in summer, at the height of the monsoon. Both are far below freezing, and that is the whole point: Everest has no warm season, only a less severe one.

The extremes matter more than the averages for anyone standing there. The lowest temperatures, on a bad winter night on the summit ridge, approach −60 °C (−76 °F). Exposed skin freezes in minutes at that, and that is before the wind is counted.

Air cools as it rises and expands, at roughly 6.5 °C per 1,000 m. That single rule explains most of the mountain. Kathmandu sits at 1,400 m; the summit is 7,450 m higher; multiply and you have lost about 48 °C before anything else is considered. A pleasant 20 °C morning in the capital is −28 °C at the top of the mountain on the arithmetic alone.

The rest of the difference is radiation and wind. Thin air holds little heat, so the ground gives up its warmth to the sky the moment the sun is off it — which is why the temperature on a Himalayan slope can drop 20 °C in the hour after sunset, and why every helicopter flight into the Khumbu is a morning flight.

From October to May the subtropical jet stream sits directly on the summit of Everest. Sustained winds over 160 km/h (100 mph) are ordinary in that period, and the plume of snow blowing off the summit ridge that appears in most photographs of the mountain is the jet stream made visible.

Wind chill turns a survivable air temperature into an unsurvivable one. At −30 °C with a 100 km/h wind, exposed flesh freezes in well under five minutes. This is also why the climbing season is so short: the jet stream lifts north as the monsoon arrives, the summit winds fall away for a few weeks in May, and that lull — not the temperature — is the window everyone is waiting for.

Everest Base Camp is at 5,364 m (17,598 ft), almost three and a half kilometres below the summit, and its weather has very little to do with what is happening up there. A clear spring day at base camp is around 0 °C to 5 °C in the sun and genuinely pleasant out of the wind. The night that follows is −15 °C to −20 °C.

Lower still, the numbers become ordinary. Namche Bazaar at 3,440 m runs from −8 °C to 12 °C across the year, and Lukla at 2,845 m is milder again. Trekkers who have read the summit numbers frequently over-pack for the valley and under-pack for the two hours after sunset, which is the part that catches people.

For a helicopter passenger this is the practical span: you take off in Kathmandu at about 10 °C before dawn and step out at Kala Patthar, 5,545 m, into something between −10 °C and −15 °C with rotor downwash on top of it. That is a jacket, hat and gloves worn on the aircraft, not packed in a bag.

Yes. The peak sits permanently above the freezing level, so snow that falls there never melts — it is scoured off by wind or compacts into the ice cap. The mountain's rock only shows where the slope is too steep or too wind-blasted to hold snow at all.

What does change is how much. Post-monsoon in October the mountain carries its deepest cover; by late winter the jet stream has stripped the upper ridges bare enough that climbers describe them as blue ice rather than snow.

Nobody measures the summit of Everest in real time in the way a city weather station is measured. Automatic weather stations have been installed high on the mountain since 2019 — the highest around 8,430 m on the Balcony — and they have transformed what is known about conditions up there, but a figure presented as "the temperature on Everest right now" is almost always a model output for a grid square, not a reading.

Treat any live summit number, including ours if we ever publish one, as an estimate with a wide error bar. The climatology on this page is the more useful thing to plan around: it is what conditions have actually been, month by month, over decades.