Color-temperature relations at a range of metallicities. Left: new empirical T_eff(J − K_S) relations compared to relations from the literature. Black lines show our new empirical relations based on samples from Levesque et al. (2006, squares) and Davies et al. (2015, circles). Gray lines show the empirical relations from Britavskiy et al. (2019a, LMC i band) and Britavskiy et al. (2019b, SMC i band) and the theoretical relations from Neugent et al. (2012, MARCS) and Yang et al. (2020, atlas). Right: effect of metallicity on the new theoretical T_eff(J − K_S) relations. We demonstrate the relation for the LMC metallicity with a dash-dotted gray line and the fit from Neugent et al. (2012) with a solid blue line. The gray shaded area indicates the effect of metallicity between the most extreme values of our grid (0.1–1.8 Z_⊙).