Pansies and Violas are hardy plants and will survive a frost—and even a hard freeze—for a period of time. Depending on how hard the frost was, flowers that were blooming may wither, but the plants will stay alive. The future buds are protected down in the crown of the foliage, and will emerge when air temperatures rise again.
When temps fall below 10 degrees for several hours, this is extreme cold for Pansies and Violas. The roots cannot absorb water from the frozen soil. This is usually most apparent in shady beds and northern exposure settings. Frozen soil and drying winds can kill the plants, even though the plants were healthy prior to that. Snow cover actually helps the pansy beds, as it insulates and protects from wind.
The Triad has seen some of its coldest weather in many years. Your Pansy or Viola beds may indeed suffer more damage this winter than in past years because of this fact. You can help the surviving plants by fertilizing lightly once temperatures begin to warm in late February and early March.
Ornamental cabbage and kales were also hit by the excessive cold this year. While they also are fairly hardy, and in most years will provide needed color and texture in winter months, this latest blast of cold probably killed most of them in the area. If your cabbage or kale have turned a light tan color, they should be pulled out and disposed of.