Extreme weather events have increased and are causing severe impacts on the electricity grid. Heat waves and ice storms are becoming more intense and frequent in Ontario, Canada. During an extreme weather event, the electricity demand fluctuates and the reliability of the electrical grid decreases due to equipment failure and shortage of electricity supply, which leads to blackouts. An initial stage simulation model is developed using the computational technique agent-based model. This thesis analyzed the impact of extreme weather events based on severity and frequency levels on two sector of Ontario’s electricity grid which are generation plants and distribution network. The simulation output showed multiple grid failures in different regions during extreme severity levels and increased frequencies of weather events. The model also showed heat waves and ice storms resulting differently depending on the month, extreme temperature months were more prone to failures than average temperature months.