In Matthew 24:26 "desert" signifies a remote place. You will not find the true Messiah out there in some remote place. If someone claims that the true Messiah is located in some remote place, don’t be deceived. Or, if they claim that He is to be found in secret chambers or in a private room, don’t believe them. The Greek term "private room" is also found in Matthew 6:6 where the Lord was recommending private prayer, rather than public prayer for the purpose of being seen by men. The Lord’s coming will not be a private affair, known by only a few people. You will not find Him in some secret location. On the contrary, His coming will be a public affair, known by everyone. "Every eye will see Him" (Rev. 1:7). The world will not miss this event. No one will say, "I wonder if the Lord has come back to earth?" It will be clear and obvious to all. His coming will not be obscure in any way.
Matthew 24:27 cements the point further by using the illustration of a huge lightning storm, one that lights up the entire sky. A lightning storm is very public, very dramatic, very noisy, very spectacular, very hard to miss. The whole sky lights up. So also the Lord Jesus will come in power and great glory and there will be no mistaking His return. The whole world will witness this spectacular event.