I'm not entirely sure why. Perhaps it is the difference between obtaining the data from the weather channel licenced host 'xoap' vs the 'xml' data. I'm pretty sure pjjameso is using the xml hack. I myself am using the xml data. I will try it out to see if it works.

licence site: socket.write("HOST:xoap.weather.com \r\n");
xml hack: socket.write("HOST:xml.weather.com \r\n");