Temperature is the ONLY factor that changes K. For exothermic reactions ($delta_H$ < 0), increasing T decreases K (shifts left). For endothermic reactions ($delta_H$ > 0), increasing T increases K (shifts right). Water's autoionisation is endothermic: H2O <=> H+ + OH-, so Kw increases with temperature. At 25 degrees C, Kw = 10^-14. At higher temperatures, Kw > 10^-14, so pH of neutral water < 7 (but it's still neutral because [H+] = [OH-]). At 60 degrees C, Kw approximately equals 10^-13, so neutral pH approximately equals 6.5. Remember: neutral means [H+] = [OH-], not necessarily pH = 7.