When is the best time to trek to Everest Base Camp?

Autumn has the clearer air and the more reliable views. Spring has the warmer nights and the climbing season at base camp. Most pages present the two as equal and leave it there, which helps nobody decide.

The afternoon is the part that gets left out. Spring mornings are usually clear, and then haze and cloud build up the valley through the day as the air warms. By early afternoon the big peaks are often gone. In autumn that happens less and later. If the photograph is the reason you are coming, that single difference should decide your season, and in spring it makes the mountain a morning job.

Spring pays you back in two ways that autumn cannot. The first is the night. You sleep better at 4,410 m (14,469 ft) and above in April than you do in November, and sleep is what most people run out of before they run out of legs. The second is base camp itself. The expeditions are there in spring, so the glacier carries a city of tents, and the walk up has yak trains and load carriers moving with you.

There is one piece of evidence for that which does not come from an operator. The Himalayan Rescue Association staffs a clinic at base camp in the spring season and not in the autumn, because spring is when the climbers are there.1 It also gives a free talk on altitude illness to anybody who walks in, and its published schedule is Daily at 3:00 pm at its aid posts during the trekking season.1 The phrase to notice in that sentence is during the trekking season. In December and in July, that talk is not running.

Put plainly: autumn is the safer bet and spring is the better story. A first timer who wants the highest chance of seeing what they came for should book autumn. A returning walker who has already had the view, or who feels the cold, should book April.

Every month of the year is walkable and only two of them are easy to sell. What follows says who each month suits and who it does not, including the months most operators will quietly steer you away from.

Read those twelve as a ladder rather than as good and bad. October and April are the two we would book without asking anything else. November, late September and March are strong choices for a walker who wants fewer people. May, December, January and February are real treks with a named cost. June, July and August are for people with spare days and a reason.

This page publishes no monthly temperature and no rainfall figure, because we do not yet hold either in a form we can stand behind. Every rival page on this query has a table. Ours would be a table of numbers nobody checked.

Two problems sit in the data we inherited. Our own older pages carry two temperature tables that disagree with each other about the same villages, so at least one of them is wrong. The monthly table states no elevation at all, and a daytime temperature means nothing on this trek unless you know whether it describes Lukla at the bottom of the walk or base camp at 5,364 m, which are a long way apart in both height and feel.

Our fact store marks those rows unsettled, and the software that renders a fact refuses to print a row in that state. That is the guard doing its job. When we have a weather authority behind a monthly table, we will publish it and say who it came from and when we read it.

The Everest Base Camp weather page, by elevation and by month takes the same problem apart in full, shows you the contradiction in our own inherited tables, and tells you what you can act on instead. That page owns temperature. This one owns the decision about which month to book.

The busy stretch runs from early October through late November, and October is the busiest month of the year. Spring has a second peak, from the start of April into the first week of May. Those are the weeks when a bed and a flight seat stop being things you can arrange late.

Busy on this trail does not look like a queue. It looks like lodges that are full by the middle of the afternoon, groups doubled up in rooms that normally sleep two, and a dining room that is packed and warm for a few hours after dark and cold again by the time you go to bed. The effect is strongest near the top of the route, where there are only a few lodges and every bed in them is spoken for in season.

It also decides who gets a room. A guided group with a relationship to a lodge gets beds on a night when a walk in trekker is told the place is full. That is not a threat, it is how the system works, and it is one of the practical reasons people book an operator for October rather than walking in.

We are not going to hand you a trekker count for October. Visitor numbers for Sagarmatha National Park circulate widely and we have not managed to verify any of them against the park itself, so turning one into a number on this page would be exactly the thing this site exists to avoid.

The quiet months are real and they are the mirror image. December, January and February give you an open trail with a narrower choice of lodges. June, July and August give you an empty trail and unreliable flying. If solitude is worth more to you than certainty, that trade is available in eight months of the year.

The season decides two things about your flight: where it leaves from, and how likely it is to fly on the day. Both of those matter more to your trek than the temperature does.

In the two peak windows, Lukla flights do not leave from 1,400 m (4,593 ft). They are moved to a second airport several hours east by road, which turns your first morning into a drive that starts in the dark. This is the single most underexplained piece of logistics on this trek, and it is the reason people arrive at the airstrip already tired.

That paragraph carries the hollow circle because it is not settled. No Civil Aviation Authority notice has reached us, so the windows above are reported dates that several independent sources agree on rather than a published rule, and they move year to year.2 We confirm the departure airport for every trek we run before anybody books a hotel for their first night.

Reliability is the other half. Autumn is the season the flight holds to its schedule best. The monsoon is the season it holds worst, with cancellations that run into days rather than hours. Winter sits in between: clear and stable for long stretches, then closed for a day when snow or wind arrives.

The answer is the same in every season and it is cheap: build one or two spare days into the trip around the flight, and build two if you are coming in the monsoon or in winter. A spare day you do not use is a day in Kathmandu. A spare day you did not buy is a missed international flight. The full picture, including why we publish no fare, the airlines, and what happens when the flight does not go, is on the page about the Lukla flight and what happens when it is canceled.

Two Khumbu festivals fall inside months people trek in. Mani Rimdu is held in the autumn at Tengboche, 3,860 m (12,664 ft), and Dumji is held in the early monsoon at Namche Bazaar and the villages around it. Neither is staged for visitors, and both are open to you if you are there.

The table below is the recommendation we give on the phone, written down. Find the row that describes you and read the month beside it.

One row is missing on purpose. There is no month we recommend for a first timer who is also on a fixed return flight with no spare days, because that combination is what turns a weather delay into a failed trip. Buy the spare days, whichever month you pick.

The month changes the sky, the crowd and the flight. It does not change the altitude, and the altitude is what this trek asks of you.

You climb the same profile in October as you do in January. The two acclimatization nights sit in the same places, the air holds the same amount of oxygen at the same height in every season, and the rule about climbing high and sleeping low applies in April exactly as it applies in December. A clear forecast does not buy you a night off the schedule, because the itinerary sets the pace, and a good forecast has never prevented a case of altitude sickness.

Three other things stay the same whatever month you book. You need both permits in every season. You walk the same distance on the same trail. And the day that breaks people is the same day, the long one to the top, regardless of what the sky is doing. If you want the full picture of what altitude does and how we manage it, that is on the page about altitude sickness on the Everest Base Camp trek.

A fixed window in a difficult month is workable, and there are four things to do about it, in this order. Most people only do the last one, which is why the month gets the blame.

Move the window by one or two weeks first, if there is any give in it at all. The months next to the good ones are much closer to them than the calendar suggests. Late September behaves like October more often than it behaves like August, the first half of December behaves like November, and the middle of March behaves like April with fewer people.

Buy time around the flight second. One spare day in autumn and two in the monsoon or in winter is the difference between a delay and a canceled trip. The detail sits on the page about flying to Lukla and what happens when the flight does not go.

Change the shape of the trip third, not the month. A slower profile with an extra acclimatization night is worth more in a cold month than in a warm one, because cold and poor sleep both work against how you adjust to the altitude. What that looks like day by day is on the Everest Base Camp trek itinerary, day by day.

Pack for the month you actually have, last and properly. A December trek and an April trek are different equipment lists, and the one that gets people is the sleeping bag rather than the jacket. The full Everest Base Camp packing list, with what to rent in Kathmandu covers both.

If your only window is July, we will still run it. You will get cloud, mud below Namche Bazaar, a green valley almost to yourself, and a real chance of losing a day or two to the flight. That is the trip. We would rather write it down here than have you find it out at the airstrip.

Every number above is listed here with the body that publishes it and the date we last read it. If a figure has changed since, write to us and we will correct the page and say that we did.