vb.net用newtonsoft解析JSON出现错误求助

[RRMMXP]

json:
[{"tmp": "13.3", "hmt": "38.4", "time": "00:00"},{"tmp": "13.2", "hmt": "36.9", "time": "00:59"},{"tmp": "13.1", "hmt": "36.8", "time": "02:00"},{"tmp": "13.0", "hmt": "36.7", "time": "03:00"},{"tmp": "13.0", "hmt": "36.7", "time": "04:01"},{"tmp": "12.9", "hmt": "36.6", "time": "05:02"},{"tmp": "12.8", "hmt": "36.5", "time": "06:02"},{"tmp": "12.8", "hmt": "37.4", "time": "07:03"},{"tmp": "12.9", "hmt": "38.9", "time": "08:04"},{"tmp": "12.9", "hmt": "41.8", "time": "09:04"},{"tmp": "13.2", "hmt": "42.1", "time": "10:05"},{"tmp": "13.3", "hmt": "40.5", "time": "11:06"},{"tmp": "13.5", "hmt": "40.5", "time": "12:06"},{"tmp": "13.6", "hmt": "38.9", "time": "13:07"},{"tmp": "13.5", "hmt": "38.8", "time": "14:08"},{"tmp": "13.5", "hmt": "39.8", "time": "15:08"},{"tmp": "13.4", "hmt": "40.1", "time": "16:09"},{"tmp": "13.3", "hmt": "40.5", "time": "17:10"},{"tmp": "13.3", "hmt": "46.5", "time": "18:10"},{"tmp": "13.3", "hmt": "47.6", "time": "19:11"},{"tmp": "13.3", "hmt": "46.2", "time": "20:11"},{"tmp": "13.3", "hmt": "45.4", "time": "21:12"},{"tmp": "13.2", "hmt": "43.3", "time": "22:13"},{"tmp": "13.2", "hmt": "42.3", "time": "23:14"}]
valno里面就是上面json的内容
Dimcontent As Object = CType(JsonConvert.DeserializeObject(valno), JObject)
出现：无法将类型为“Newtonsoft.Json.Linq.JArray”的对象强制转换为类型“Newtonsoft.Json.Linq.JObject”.
求助