As power systems continue to expand with continued electrification and both the demand and the supply of electricity becomes more weather-dependent, ensuring the security and reliability of electricity supply is imperative. Many power systems around the world face adequacy issues during periods of elevated electricity demand, such as during peak seasonal heating needs in winter and cooling in summer. Extreme weather due to winter storms or intense heatwaves, especially when compounded with impacts on the supply side such as droughts, fuel supply disruptions or power plant outages, can put significant strain on the power system.

Extreme weather events such as storms, droughts and heatwaves led to widespread power disruptions in 2024. Large-scale power supply interruptions plagued a broad swath of countries and regions. In the United States, massive winter storms in early January led to large-scale outages across multiple states. The Atlantic hurricane season was particularly intense, bringing severe storms that disrupted power supplies in several US states and Caribbean nations. In Australia, Victoria experienced a major outage when a storm damaged key transmission infrastructure. Meanwhile, droughts reduced hydropower output worldwide, with Ecuador and Colombia significantly impacted by El Niño conditions. In Mexico, heatwaves and low hydropower generation created supply shortages during peak demand. These events underscore the urgent need to enhance the resilience of power systems against extreme weather.

As electricity makes up a larger share of final energy demand, safeguarding its supply is key to ensure a range of services vital for modern societies. Recent power shortages underscore evolving uncertainties in the power sector to consistently meet demand, particularly under extreme – yet possible – conditions.

Historically, in power systems dominated by fossil fuels and large generators, supply shortages often stemmed from a combination of unrelated outages of large generators or interconnectors during periods of high demand. In emerging economies, these challenges were at times compounded by rapid demand growth outpacing new supply, leading to systemic load shedding to manage shortages.

Looking forward, growing risks stem from changing weather patterns and extreme weather events. In particular, extreme weather events have been identified as the main risk to reliability in many regions, for example by the North American Electric Reliability Corporation (NERC), which can have simultaneous, large impacts on power generation, grids and demand. These events can also put upstream fuel supply at risk, particularly evident for natural gas in freezing conditions if the infrastructure is not winterised sufficiently. Thus, power shortages due to extreme weather events can have a much wider impact, particularly if their effect on electricity demand and renewables output is coupled with thermal generator outages or fuel supply risks.

In this context, resource adequacy refers to the ability of power systems to reliably balance electricity supply and demand within an area under normal conditions in terms of weather and generator outages (among others), with the precise definition of normal conditions varying by jurisdiction. Adequacy is normally analysed in forward-looking studies that assess whether the available resources would allow the power system to meet certain reliability targets – such as specified limits on loss of load hours – in the period and conditions analysed.

Recent events have highlighted adequacy risks worldwide. At the same time, several jurisdictions have been improving their resource adequacy studies, aiming to be better prepared for evolving demand, generation and weather conditions. In light of the increasing impact of weather on power systems. The need to incorporate the stochastic nature of weather impacts and the evolving changes on the generation and demand side into these assessments is becoming more important. Our analysis of recent adequacy-related power shortages illustrate that there is a range of measures that can be implemented. Improvements in adequacy assessment methods, adoption of more refined and multiple metrics in adequacy studies and more universal reliability standards could all help more effectively manage simultaneous and widespread impacts on power generation, grids and supply.