How hot are the 10 closest stars?

They vary. Not counting the Sun itself, the 10 closest (known) stars are spectral classes M5, G2/K1, M4, M6, M2, A1/DA2, M5 and M6 (the slashes represent close binaries where there are two stars at effectively the same distance). The Ms have surface temperatures of less than about 4000K. The K has a surface temperature of about 5200K, the G is around 5800K, the A is around 10000K, and the DA is roughly 25000K.