A research topic that is becoming increasingly popular is that of on-board mobile communication, where users on a vehicle are connected to a local network that attaches to the Internet via a mobile router and a wireless link. One critical issue in such a moving network architecture is the possibility of temporary outages due to low quality of wireless links between on-board routers and base stations. In an onboard communication network, a single link outage may impact a large number of existing connections. The ability to predict link outages before they occur, which becomes possible when the route of the vehicle is known in advance (e.g. for public transport), can significantly improve the performance of on-board moving networks. In this work, we show some results on the impact of different factors on the signal strength in a metropolitan area. Our study suggests that location is a promising factor in the context of outage prediction for on-board mobile networks. We observe that signal strength is strongly correlated with locations across different times of a day. Additionally, we find that, while the signal strength levels measured at low and medium speeds are similar, there are larger variations and more frequent handoffs at a lower speed. These insights may be useful for designing realistic detailed simulations.