Dear Janice,
Thanks for contacting Top China Travel!
The average temperature in Zhangjiajie in April is about 17 degree. It is hot during the day, and the highest temperature might reach 30 degree, and recommending to wear ramie cotton fabric clothes, light longuette, light t-shirt in the day time; the lowest temperature might be 11 degree and recommending to wear suits, wind coat, light sweater etc,.
Any further request or question, please feel free to contact with us.