A radio frequency power delivery system comprises an RF power generator, arc detection circuitry, and control logic responsive to the arc detection circuitry. A dynamic boundary is computed about the measured value of a parameter representative of or related to the power transferred from the power generator to a load. A subsequently measured value of the parameter that exceeds the computed dynamic boundary of the parameter indicates detection of an arc. Upon detection of an arc, power delivery from the generator is interrupted or adjusted, or other action is taken, until the arc is extinguished. By employing dynamic computation of arc detection boundaries, the invention allows for arc handling in RF power deliver systems regardless of whether the system has reached a stable power delivery condition.