Depends where you walk. Fresh lava (and there's a good bit of that!) would melt most space suits, making hikes on Io precarious at best. A large eruption on Io launches (since there's less gravity to pull it down) lava up to 100 miles away, with little time to get out of the way. The solid surface is relatively cool since most of the heat is released through volcanic activity, but large pools of lava can reach nearly 400 F. Have a look at http://pds.jpl.nasa.gov/planets/welcome/jupiter.htm for more info and pictures.

Actually, the average temperature is -146 Celsius (-229 Fahrenheit).The volcanoes spew out sulfur gas, but it's not all that hot... near the volcanos it's 20 Celsius (77 Fahrenheit). You'd have to worry about freezing to death, actually.

Io, it turns out, is pretty cold in general (about -140 degrees Celsius). Even the parts near the "volcanos" are only about 20 degrees Celsius (about room temperature here on Earth) Of course you would want to avoid being too close to a volcano because the material that comes out is pretty hot, but it cools very rapidly. Why do you think Io is so cold?