AbstractThe continuously increasing temperatures worldwide indicate the frequently extreme heat in summer will become a new normal. The extreme high temperature (EHT) could be dangerous to human health, especially for outdoor workers or commuters, and increase the risk of grid collapse. Thus, the possibility of a day-off due to EHT has started to be discussed in Taiwan, based on the experience of typhoon day-off, but not yet concluded. In this study, the effects of the EHT day-off on electricity consumption in the industrial, service, and residential sectors was investigated through two determinants: First, high temperature would increase the electricity consumption in space cooling. Second, a day-off would change people’s behavior of electricity consumption from workday to non-workday modes. Combining the effects of cooling hours and non-workdays, the net influence of the EHT day-off on electricity consumption can be evaluated. Estimated results indicated that an EHT day-off can reduce aggregate electricity consumption by between 0.41% and 1.08%. The reduction of electricity consumption due to the off-day offsets the increase driven by high temperatures. Thus, an EHT day-off will mitigate the pressure of power grid and be of benefit to electricity conservation.