Green-up of warm-season grasses was ahead of schedule in March. In Raleigh we were in the 20s on February 27 before we had an extended warming trend. In March, Raleigh enjoyed 15 days with highs in the 70s and two days in the 80s. Exactly what the grass needed to get it out of dormancy and actively growing. Even with a couple of nights around the freezing mark on March 5 and March 22, it did not seem to slow down the grass to any great extent.
Then April 6 we had a hard freeze and April 10 another night just below freezing. These episodes desiccated the green leaf tissue and put a lot of the warm-season grasses back into a semi-dormant condition. If the grasses had some overhead trees there may have been enough trapped heat that they may not have lost much color. Those in wide-open areas had greater influence from the cold temperatures.
I do not think this has caused much winterkill. It is causing the turfgrass plant to pull from its reserves, so green-up this second time is progressing slowly.
The forecast for the next week or two suggests continued warming, which will be good to get the grasses green and growing again. In many cases all the site needs is some time and warmer weather combined with reasonable fertility/irrigation practices.