Sapere prepared a report for the Australian government on the impact of extreme weather events on the National Electricity Market, as part of preparation for a third National Energy Security Assessment (NESA). The first part of the report is an historical analysis of data and reports on extreme weather events. It identifies historical linkages between extreme weather, demand, price, plant outages, ‘credible contingency’ events and loss of supply, since 1998. Part two develops a “stress”, extreme heatwave scenario to assess the resilience of the NEM’s physical and market operations during prolonged, extreme heatwaves over the short- to medium-term (up to five years).