Nowadays arc surface treatment has several important applications in manufacturing of highvoltage switching equipment. Experimental study of arc discharges is a challenging task [1] and has certain limitations related to detailed resolving of discharge local features. The latter promotes researchers to develop numerical tools for quantitative analysis of such features [2, 3], particularly in LTE plasma of atmospheric open air arc discharge. In terms of electric subsystem, arc discharge is driven by two major factors which divide the problem into two subtasks. They are an evolution of the plasma column geometry [4] and arc conductivity dynamics [3]. Consideration of the arc as a solid cylindrical volume of thermal plasma reduces the last subtask to investigation of the radial temperature distribution, which is discussing here. Mathematical formulating of the problem includes nonstationary energy balance equation, axial symmetry and open boundary conditions, initial conditions, the Ohm's law and equation describing the linear electric conductivity [3]. Within the numerical implementation the heat flux potential П : T dП = kdT (where k is thermal conductivity) was introduced. An adaptive time-step technique which automatically guarantees numerical stability and reasonable precision was applied. In the fig. 1 the radial temperature distributions at four time moments are presented. The moments are shown on the electric field strength waveform curve (subplot in fig. 1), which has distinctive features such as the surge nearby current zero caused by limited velocity of temperature relaxation and the slump in the current maximum caused by increase of electric conductivity at higher plasma temperatures. The temperature and its oscillations are higher in the center and decrease in outlying region. The time average radial distributions of contributions defining power balance are presented in fig. 2. The arc obtains energy by Joule heating and loses it by means of radiation and thermal conductivity. Fig. 2 shows that radiation is the main mechanism of power dissipation.