Climate change is projected to cause an increase in the severity and frequency of extreme weather events such as heat waves and droughts. Such changes present planning and operating challenges and risks to many economic sectors. In the electricity sector, statistics of extreme events in the past have been used to help plan for future peak loads, determine associated infrastructure requirements, and evaluate operational risks, but industry-standard planning tools have yet to be coupled with or informed by temperature models to explore the impacts of the “new normal” on planning studies. For example, high ambient temperatures during heat waves reduce the output capacity and efficiency of gas-fired combustion turbines just when they are needed most to meet peak demands. This paper describes the development and application of a production cost and unit commitment model coupled to high resolution, hourly temperature data and a temperature-dependent load model. The coupled system has the ability to represent the impacts of hourly temperature on load conditions and available capacity and efficiency of combustion turbines, and therefore capture the potential impacts on system reserve and production cost. Ongoing work expands this capability to address the impacts of water availability and temperature on power grid operation.