  In this essay it is proved that there are black holes that are dangerously
cold. In particular, by analyzing the emission spectra of highly charged black
holes we reveal the fact that near-extremal black holes whose
Bekenstein-Hawking temperatures lie in the regime $T_{\text{BH}}\lesssim
m^6_e/e^3$ may turn into horizonless naked singularities, thus violating the
cosmic censorship principle, if they emit a photon with the characteristic
thermal energy $\omega=O(T_{\text{BH}})$ [here $\{m_e,e\}$ are respectively the
proper mass and the electric charge of the electron, the lightest charged
particle]. We therefore raise here the conjecture that, in the yet unknown
quantum theory of gravity, the temperatures of well behaved black-hole
spacetimes are fundamentally bounded from below by the relation
$T_{\text{BH}}\gtrsim m^6_e/e^3$.
