Mount Everest without the crowd

From Wikitravel:

While trekking is possible in this area the whole year round, the best times to visit are from the beginning of March to mid May and from the beginning of September to mid November.

So I guarantee that those are going to be the busiest times, as people go for the best weather, conditions and not-too-freezing temperatures.

So if you're looking to avoid those, you'll want to go outside of these two windows.

MountainKingdom suggests that if you want to avoid crowds:

Perhaps the very best time of the year though to go is mid-late November when trails and tea houses see fewer trekkers and the weather is mainly fine and clear during the day, providing wonderful views at every step. It will be colder though, especially at night and at higher altitudes, but well-layered clothing, a good four-season sleeping bag and a warm duvet jacket will help keep you snug. And, being a bit chilly, is a small price to pay to escape the crowds.

He also points out that if you can handle the cold, Christmas is a fun time to go, but I suspect that will draw others during their Christmas break.

As a matter of fact, this questions was asked frequently in the forum and I guess this is very important to know for all Everest Base Camp hiking enthusiastic. During the busy season (October, November - March, April) over 500 tourist fly to Lukla makes this trail one of the busiest trails in Nepal. Roughly Over 40k tourist travel EBC in a yearly basis. September let me come to the point, A lot of online and even Wikipedia says September is the best and less crowd in the Everest Himalayas. As a matter of fact it is less crowded but certainly, it's not a good time. Past couple of years due to the none stop Monson making harder to catch the flight to Lukla during the September also the sky is not clear as it supposed to be. Especially the trek is being more challenging in the month of September after the [landslide took lives of 4 Spainese tourists in Mount Manaslu region (The 8th Highest mountain in the world) December This is probably the best time as the sky will be nice and clear and especially EBC Trek has a much low crowd during the month of December. I would Highly recommend EBC during the month of December If you are thinking of avoiding the crowds and the winter in Nepal will not start until the first week of January. May The month of May is also considered the best time of year to trek Everest Base Camp. As the monsoon hasn't started yet and remained spring season also pushing a best and clear sky. if you really want to avoid the traffic the month of May to until 2nd week of June is the best time.