a false dawn
A situation that looks like it is beginning to improve when, in reality, it is not. Barb thought her marriage was beginning to improve when her husband came home in a good mood, but it proved to be a false dawn when he handed her divorce papers. Everyone was happy when they heard that they were all getting a raise, but it turned out to be a false dawn when management cut all of their hours.
a false dawnmainly BRITISH, JOURNALISM
COMMON If an event is a false dawn, it seems to show that something is improving or something successful is happening, but in fact it is not. The new age of enterprise which the Government hoped would revitalise Britain in the Eighties turned out to be a false dawn. Everything they have said is sensible but we have had a lot of false dawns with this company before.
a false dawna misleadingly hopeful sign.
A false dawn is literally a transient light in the sky which precedes the rising of the sun by about an hour, commonly seen in Eastern countries.
1992 Frank McLynn Hearts of Darkness After five weeks Clapperton seemed to recover; it proved merely a false dawn for two days later Clapperton died.