As mentioned, a USB dongle with an external Yagi or other directional antenna is your best option.
Businesses that offer WiFi often configure their networks to prevent or lessen outdoor use. Mostly so you'll come in and spend money....or appear on camera if you're involved in some sort of illegal online activity.
Google "Pringle can Wifi antenna" if you're interested in building your own directional antenna. A directional antenna is key, as the Wifi bands are crowded. Especially 2.4GHz, which is also home to Bluetooth, cordless phones, and tons of Wifi traffic...
Roof-top mounted Antennas Direct DB8e & C5, Channel Master 7777 preamp, Siemens surge protection. TiVo Roamio DVR