By: Matt Emma
Record-breaking heat swept across Europe and the United States during the summer of 2026. Extreme heat places extraordinary pressure on the electric grid as millions of homes and businesses rely on air conditioning, pushing electricity demand toward peak system capacity. Energy strategist Emily Sanford Fisher says maintaining reliability during a major heat wave depends on preparation that begins well before temperatures climb.
“Grid operators don’t wait until a heat wave arrives to begin preparing,” Sanford Fisher explained. “They use weather forecasts, demand projections, and real-time system data to understand where electricity demand is likely to be highest and identify any potential reliability risks well in advance.”
How Grid Operators Forecast Electricity Demand
Grid operators spend weeks monitoring weather forecasts and electricity demand projections to understand how a developing weather pattern could affect the power system.
Meteorologists provide detailed predictions for temperature, humidity, cloud cover, wind speeds, and the duration of a heat wave. Those forecasts are combined with historical electricity consumption patterns, real-time system conditions, and regional demand models to estimate how much electricity consumers are likely to use.
“Meteorologists are always in demand in the power sector,” said Sanford Fisher.
Preparing The Grid For Peak Demand
Once forecasts indicate that extreme heat is approaching, local grid operators begin working with power plant operators to schedule generation resources and confirm that facilities are ready to operate during peak periods. They also coordinate with transmission operators to maximize the availability of transmission lines so electricity can be delivered where it is needed most.
“Grid operators also reach out to customers who have agreed to reduce their consumption during peak demand in exchange for compensation, reducing some of the stress on the system,” said Sanford Fisher. “These customers need to be ready to change behavior, limiting production of certain products, turning the air conditioner up, or shutting off non-essential equipment, if needed.
“During the historic September 2022 heat wave in California, this kind of demand response and public conservation efforts successfully reduced peak electricity demand by more than one gigaWatt, a huge amount of power, which helped avoid widespread rolling blackouts when demand hit an all-time record,” explained Sanford Fisher. “These kinds of measures can really make a difference.”
Balancing Electricity Supply And Demand
Every day, grid operators work to ensure that supply and demand for electricity are matched at every moment. This is the key to reliability, even during normal weather.
It is more difficult and even more important to maintain the balance between demand and supply during heat waves,” said Sanford Fisher. “Too much demand and too little supply upset the careful balance that keeps our interconnected grid safe and reliable,” said Sanford Fisher. “When demand exceeds supply because everyone is cranking up the air conditioning, we risk losing power for everyone.”
Grid operators have several tools available to increase electricity supply and manage changing system conditions. Battery energy storage systems can discharge electricity during peak demand, helping balance short-term fluctuations on the grid. Operators can also dispatch fast-start natural gas plants, increase output from hydroelectric facilities, or bring reserve generating units online.
Because much of the U.S. electric grid is interconnected, electricity can also be imported from neighboring regions when transmission capacity is available. “The interconnected nature of the energy grid is one of its greatest assets,” said Sanford Fisher. “The ability to transfer power between regions is important when the heat is turned up in a particular place, but transfer capability can be limited between regions, and two regions can experience extreme heat at the same time, reducing the amount of “excess” power that can be shared,” she continued. “Importing power is an important tool, but it isn’t a silver bullet when temperatures are high.”
Control centers continuously manage electricity flows across transmission lines to reduce congestion and direct power where it is needed most.
“Grid operators are continually adjusting available resources as conditions change,” Sanford Fisher said. “The objective is to maintain the balance between electricity supply and demand while preserving as much operational flexibility as possible.”
If demand continues to approach available supply, operators may issue voluntary conservation requests, encouraging consumers to reduce electricity use during peak hours by adjusting thermostats, delaying the use of major appliances, or limiting other non-essential electricity consumption. These collective actions can help stabilize the grid during periods of exceptional demand.
Controlled rolling outages are considered only after other operational measures have been exhausted. These temporary, rotating outages are designed to prevent uncontrolled system-wide failures and protect the integrity of the broader electric grid.
“No single tool can maintain grid reliability during a major heat wave,” Fisher concluded. “Maintaining reliable service depends on combining demand response, energy storage, dispatchable generation, transmission management, regional coordination, and consumer participation as conditions evolve.”
Reducing Risk Before The Heat Arrives
To reduce the risk of unexpected equipment outages, non-essential maintenance on generation and transmission infrastructure may be postponed until after the heat wave has passed. Control centers also increase operational staffing so personnel are available to continuously monitor system conditions and respond quickly if operating conditions change.
“Not every generator is ‘on line’ all of the time,” explained Sanford Fisher. “Sometimes units are offline for maintenance or upgrades. These periods are usually scheduled. When a heat wave is coming, grid operators ask unit operators to defer maintenance or other scheduled outages and stay online to meet surging demand.” She continued, “More recently, units that are preparing to retire are often kept operating, at reduced levels, to be available to respond when extreme heat is in the forecast.”
Lessons From Recent Heat Waves
Record-breaking heat waves have pushed electricity demand beyond historical levels.
“California’s September 2022 heat wave is one of the strongest examples of how coordinated planning can improve reliability,” explained Sanford Fisher. “As electricity demand reached a record of more than 52 GW, grid operators relied on battery storage, demand response programs, public conservation requests, emergency generation, and electricity imports from neighboring states to avoid widespread outages. The event demonstrated that maintaining reliability depends on having multiple tools available.”
“Every major weather event provides new operational data that planners can use to improve future reliability,” Sanford Fisher said. “The objective isn’t to prepare for the last heat wave; it’s to understand how demand patterns, resource availability, and system performance are evolving so operators are better prepared for the next one.”
About Emily Sanford Fisher
Emily Sanford Fisher is the founder of Enodia Energy, where she advises utilities, regulators, industry groups, and nonprofits on electricity markets, transmission policy, grid modernization, and long-term energy strategy. She previously served as Chief Strategy Officer at the Smart Electric Power Alliance and as Executive Vice President, Clean Energy, and General Counsel at the Edison Electric Institute.
