Volatile memristors are versatile devices whose operating mechanism is based on an abrupt and volatile change of resistivity. This switching between high and low resistance states is at the base of cutting edge technological implementations such as neural/synaptic devices or random number generators. A detailed understanding of this operating mechanisms is essential prerequisite to exploit the full potentiality of volatile memristors. In this respect, multi-physics device simulations provide a powerful tool to single out material properties and device features that are the keys to achieve desired behaviors. In this paper, we perform 3D electrothermal simulations of volatile memristors based on vanadium dioxide (VO2) to accurately investigate the interplay among Joule effect, heat dissipation and the external temperature T over their resistive switching mechanism. In particular, we extract from our simulations a simplified model for the effect of T over the negative differential resistance (NDR) region of such devices. The NDR of VO2 devices is pivotal for building VO2 oscillators, which have been recently shown to be essential elements of oscillatory neural networks (ONNs). ONNs are innovative neuromorphic circuits that harness oscillators’ phases to compute. Our simulations quantify the impact of T over figures of merit of VO2 oscillator, such as frequency, voltage amplitude and average power per cycle. Our findings shed light over the interlinked thermal and electrical behavior of VO2 volatile memristors and oscillators, and provide a roadmap for the development of ONN technology.