In the circuits of high-power microwave (HPM) devices, such as HPM sources or high-gradient accelerating structures, small quantities of metallic dust may exist. These metallic particles of micrometer size immersed in high-RF fields can absorb enough energy for significant heating and melting. The heating effect of an RF magnetic field was analyzed in our previous papers. In this paper, we analyze the role of the RF electric field which may cause field emission from a microparticle. Our consideration is restricted by ellipsoidal metallic particles. It is shown that the heating effect becomes significant when such microparticles have a needlelike shape, and therefore, the electric field amplification at the ends is high. In this case, the field-emitted current may cause the heating of the microparticles. The heating in single shots and in repetition-rate regimes is studied for the case of the combined effect of both the RF magnetic and electric fields.