Difference in weather forecast

Recently I started keeping a track weather from multiple sources and noticed that there are sometime major differences in prediction. From what I have noticed all private companies like weather channel, accueweather and many others have a huge range of forecasts which differ in a big way from national weather services at times and sometimes prediction of rain/snow is way off. I have installed a small weather monitoring system outside my home and noticed difference in 3-5' in temperature at times and on lot of occasions wind direction is also way off as predicted by these apps.

HN - Is there a best resource online where you can seek more accurate local weather or get data to play with yourself?