<p>This paper provides a novel testing methodology to determine the initial temperatures of ejected, arc-produced particles. Knowing the temperature of an electrical arc, and the initial temperature of any ejected particles produced from an arc, can greatly assist fire investigators in establishing the temperature and energy of the particles upon striking a hard ground surface at a hypothesized fire origin site. This paper uses both empirical testing and mathematical modeling to verify the initial temperature of these particles. The mathematical model can assist in developing key probabilistic assessments regarding hot particle ignition in wildland fire investigations. This paper presents a methodology that uses a mathematical model to predict the temperature and phase of ejected, arc-produced particles of varying sizes relative to their vertical travel. The model accounts for the possibility of an isothermal liquid-to-solid phase change during their descent before striking a hard ground surface. Empirically, particles will become permanently deformed if they strike the ground as they enter the liquid-to-solid phase change. By predicting where on its cooling curve a particle will be deformed by impact, a researcher can then determine the initial temperature of the particle. This research determines that copper particles ejected by electrical arcing events initiate at temperatures much closer to their boiling temperature as opposed to their melting temperature. Arc-produced copper particles, ejected from a twenty-foot (6.1&#xa0;m) height, cannot be assumed to be completely solidified and uniformly spherical masses upon contacting fuel beds at ground level—these same particles can be as hot as their melting temperature (1084&#xa0;°C) upon contacting the solid ground.</p> Graphical Abstract <p></p>