I've just been looking at http://www.uavforecast.com/ for the current k so I know if I should be cautious of the GPS coverage or not, and then look at the weather by looking out the window. :-)
You should check out windfinder.com. This site and Apps are used by sailors, but I've found it great for UAVs. The Android or iOS Apps have a lot of great features. Lots of customization with respect to units. You can have wind speed in Knots, km/h, miles/h and even meters/s. It provides weather forecasting, precipitation, wind graphs and a lot more.