Free WiFi networks can be useful to get connected anywhere, but the problem is that there no easy way to find free open WiFi Hotspots, You can go WiFi hunting using WiFi Scanners like Outssider or before your leave you can check out the places around your point of interest where you can find Free Open WiFi Networks using OpenWiFiSpots.
OpenWiFiSpots is a directory of free wireless (WiFi) hotspots across the US that offer Free WiFi high speed wireless Internet access to their customers and guests and/or the general public that don’t require any login/signup.
All the hotspots can be seen as listing or as Google Map Overlays.You also refine you searches using ZipCodes, Places of interest.
While connecting to such free Hotspots, you can try out tools like HotSpotSheild – that can protect your system while using a public wifi network.
Note : This tool lets you find free public wifi networks available in the US only.