The answer to 'junction box hot to touch' is that a hot junction box is a sign of an electrical issue that requires immediate attention. This could indicate a serious problem like a short circuit, overloaded circuit, or faulty wiring that is causing excessive heat buildup in the box.
Symptoms of a hot junction box include the box feeling warm or hot to the touch, sparks or arcing inside the box, tripped circuit breakers, or flickering lights. This is a fire hazard that should not be ignored. If you notice a hot junction box, shut off power to that circuit immediately and call a licensed electrician to diagnose and repair the issue.