Winter weather can affect yews. Winter injury occurs as a result of rapidly changing temperatures during the winter, bright sunshine, winds, and inadequate water reserves in the root system of the plant. Plants usually show the first symptoms of winter injury in late winter through spring, and browning is most pronounced on the south and west sides of the plants. Although foliage turns brown, if buds remain green and viable, the plant may recover as the spring progresses.
Yews are also quite sensitive to deicing salts used on roadways and sidewalks. Plants that have been affected by these salts typically turn brown starting from the side closest the area salted. Symptoms usually first appear in the spring. When salts have washed into the soil under a yew, leaching the soil with a large amount of water may help.
We do not recommend pruning the brown off until later in the season when new growth has a chance to start. Its likely that established shrubs will recover.