To be expected after a long, unrelenting winter (January into February into March!), the blossoms are coming later than usual, projected in the middle of April. That's when the hordes of out-of-towners will descend upon the tidal basin and elbow for a prime photo opportunity that will never come (pro tip: go at sunrise for optimal light and light tourist traffic).
Of course, we will be celebrating because by then, the winter doldrums will have disappeared into glorious spring. Better late than never.