Hydrangea blooms do not stay with the same color all the time. After several weeks or around a month, the blooms fade and change colors. The exact sequence of colors that the blooms change to depends on the variety. For example, some may start a shade of pink then turn greenish then sandy/whiteish and then brown.

The blooms are also likely spent. If they broke dormancy early and aren't rebloomers, their show is done for the season. Some hydrangeas blooms last longer than others; selective breeding has yielded some that last longer, more rigid, resistant to drying/scorching, etc.

My experience is that the Macrophyllas' (assuming those are the hydrangea you are referring to) color change vary, in part, due to specific cultivar, but, in my garden, the ones that get more sun are more likely to change to purplish or burgundy, while the ones in more shade just turn green.

Are they ready to be dead headed at this point carrieb?

If they're deadheaded they don't change color - they're not there to change color... Do I misunderstand your question?