<p>The neural circuits processing thermal information play a key role in shaping somatosensory perception, regulating core body temperature and avoiding harm. The circuits underlying thermal perception are less understood than for other sensory systems, but recent research has shed light on the wiring, cellular encoding principles and their link to perception. While thermosensation was traditionally viewed as a slower, modulatory sense, it is now recognized as a fast and sensitive sensory system that exhibits complex features such as multisensory integration and sensory illusions. Here, we highlight recent progress in the understanding of innocuous thermal processing and perception and attempt to identify the principles of wiring of the thermal system and cellular encoding of temperature across mammals and insects. Intriguingly, while warm and cool reflect the same physical property, there are notable differences in their perception and encoding in the nervous system. We argue that the thermal system is an ideal model to advance our understanding of the neural mechanisms of sensory perception and sensory-guided behaviours.</p>