String jsonString =
                "{\"weatherinfo\":{\"city\":\"北京\",\"cityid\":\"101010100\",\"temp\":\"25\",\"WD\":\"西南风\",\"WS\":\"3级\",\"SD\":\"59%\",\"WSE\":\"3\",\"time\":\"16:00\",\"isRadar\":\"1\",\"Radar\":\"JC_RADAR_AZ9010_JB\"}}";
            var scriptSerializer = new JavaScriptSerializer();
            var weatherinfo = scriptSerializer.Deserialize<Dictionary<String, Dictionary<String, String>>>(jsonString);
            var detail = weatherinfo[""];
            //detail["city"];//取得北京。同样获取其他信息。

------解决方案--------------------

可以用JavaScript，比如json赋值给res
JScript code

var sJson=eval(res);
for(var i=0;i<sJson.length;i++)
{
 document.getElementById("div1").innerHTML +=
"sJson[i].city：sJson[i].cityid"+
"温度：sJson[i].temp"+
"时间：sJson[i].time"；
}