High Noon Meaning

(idiomatic) A time, set out in advance, at which an important decision is to be made or a nemesis is to be confronted

Example:   The same streets that are inviting and quiet at high noon may be intimidating at night.
1860 January 27, William Lloyd Garrison, annual meeting, Massachusetts Anti-Slavery Society, as quoted in Liberator (1860 February 3)
  […] whereas, ten years since, there were thousands who could not endure my lightest word of rebuke to the South, they can now easily swollow John Brown whole, and his rifle into the bargain. In firing his gun, he has merely told us what time of day it is. It is high noon, thank God!