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Superflares may provide the dominant source of biologically relevant UVradiation to rocky habitable zone M-dwarf planets (M-Earths), alteringplanetary atmospheres and conditions for surface life. The combined line andcontinuum flare emission has usually been approximated by a 9000 K blackbody.If superflares are hotter, then the UV emission may be 10X higher thanpredicted from the optical. However, it is unknown for how long M-dwarfsuperflares reach temperatures above 9000 K. Only a handful of M-dwarfsuperflares have been recorded with multi-wavelength high-cadence observations.We double the total number of events in the literature using simultaneousEvryscope and TESS observations to provide the first systematic exploration ofthe temperature evolution of M-dwarf superflares. We also increase the numberof superflaring M-dwarfs with published time-resolved blackbody evolution by~10X. We measure temperatures at 2 min cadence for 42 superflares from 27 K5-M5dwarfs. We find superflare peak temperatures (defined as the mean oftemperatures corresponding to flare FWHM) increase with flare energy andimpulse. We find the amount of time flares emit at temperatures above 14,000 Kdepends on energy. We discover 43% of the flares emit above 14,000 K, 23% emitabove 20,000 K and 5% emit above 30,000 K. The largest and hottest flarebriefly reached 42,000 K. Some do not reach 14,000 K. During superflares, weestimate M-Earths orbiting <200 Myr stars typically receive a top-of-atmosphereUV-C flux of ~120 W m^-2 and up to 10^3 W m^-2, 100-1000X the time-averaged XUVflux from Proxima Cen.

EvryFlare III: Temperature Evolution and Habitability Impacts of Dozens of Superflares Observed Simultaneously by Evryscope and TESS