Weather & grid risk

The short version

Weather is by far the largest cause of grid outages and reliability events. Every major US ISO has experienced weather-related crises in recent years: Winter Storm Uri in ERCOT (February 2021), the CAISO Heat Dome events (August 2020 and August 2022), Hurricane Ida in MISO and Hurricane Beryl in ERCOT, and ongoing Public Safety Power Shutoffs across the West. Climate trends are making extreme events more frequent and more intense, while resource mix transitions are introducing new vulnerabilities (gas-electric fuel coupling, inverter resource trip behavior, transmission constraints during simultaneous failures). The cumulative effect is that grid planners must increasingly design for weather scenarios that fall well outside historical norms.

Extreme cold and the gas-electric coupling

Extreme cold weather creates simultaneous problems on the supply and demand sides of the grid. Demand spikes as electric heating loads — heat pumps, electric resistance heat, and some types of supplemental heat — dramatically increase. Supply contracts as natural gas plants face fuel curtailments (heating customers have priority access to natural gas during cold weather emergencies), as wind turbines shut down in dangerous icing conditions, as coal piles freeze, and as plant equipment fails when ambient temperatures fall outside design limits. The compounding effect is severe.

Winter Storm Uri in February 2021 was the most severe modern example. More than 30 GW of generation went offline simultaneously in ERCOT as gas plants lost fuel supply, as wind turbines iced up, and as plant equipment failed. Rolling blackouts lasted days. Approximately 246 deaths were attributed to the event in Texas. The post-event response included Texas Senate Bill 3 (signed June 2021), which mandated weatherization for ERCOT generators and natural gas infrastructure. Compliance standards have been progressively tightened, with significant capital investment by generators in cold-weather hardening. Whether the post-Uri weatherization framework will hold up against future cold events is the central question stress-testing ERCOT reliability.

Heat waves and the cascading capacity problem

Extreme heat creates a different but equally serious set of problems. Air conditioning load surges to record peaks. Transmission lines sag more in hot conditions, limiting their current ratings (line ratings are often based on conservative assumptions, but in extreme heat actual capacity can drop 5-15% below normal ratings). Thermal power plants lose efficiency as cooling water and ambient air temperatures rise — natural gas turbines lose 5-10% capacity in extreme heat, and steam-cycle plants lose efficiency on hot days. Solar PV output declines as panel temperatures rise — typical losses are 0.3-0.5% per degree C above standard test conditions, meaning a 100 MW solar facility might produce 15-20% less in extreme heat than in cooler conditions with similar irradiance.

The CAISO August 2020 rotating outages illustrated how these dynamics combine. Demand exceeded forecasts; multiple thermal plants underperformed due to heat-related derating; solar resources declined as expected as evening approached but heat persisted; and imports from neighboring regions were unavailable because the same heat wave was stressing those regions simultaneously. The August 2022 Heat Dome event was even more severe in raw conditions but was managed without rotating outages, partly because of substantial battery storage buildout that had occurred in the intervening years. Battery deployment continues to be a critical hedge against summer reliability events in heat-exposed regions.

Hurricanes and the multi-week recovery

Hurricanes cause widespread, prolonged outages through multiple compounding mechanisms. High winds damage overhead transmission and distribution infrastructure (tree falls, conductor whip, structural damage to towers). Storm surge floods substations and underground equipment. Falling trees damage distribution lines. Prolonged inland heavy rain causes additional flooding. The combination is uniquely difficult to recover from because it damages infrastructure across thousands of square miles simultaneously, requires extensive line worker and equipment mobilization, and often coincides with damaged roads that slow restoration crews.

Hurricane Maria (September 2017) destroyed most of Puerto Rico's grid; restoration took nearly a year for some areas. Hurricane Ida (August 2021) left more than a million MISO customers without power for over a week. Hurricane Ian (September 2022) caused multi-billion-dollar damage to Florida grid infrastructure. Hurricane Beryl (July 2024) left over 2 million Texas customers without power for an extended period during summer heat. The repeated pattern has driven significant investment in undergrounding (where economically justified), hardened substations, vegetation management, and storm response capability — though the increase in storm frequency and intensity continues to outpace many utility hardening programs.

Wildfires and PSPS

The fourth major weather threat pattern is wildfire risk, primarily in the Western US. Electric utility equipment has been identified as the ignition source for several of California's most catastrophic wildfires — the 2017 Tubbs Fire, 2018 Camp Fire (which destroyed the town of Paradise), and others. The civil liability exposure for wildfire-caused damage has been enormous: PG&E entered bankruptcy in 2019 with approximately $30 billion in wildfire-related liabilities. In response, Western utilities have implemented Public Safety Power Shutoff (PSPS) protocols — intentionally de-energizing transmission and distribution circuits during high fire risk conditions.

PSPS events have affected millions of customers across California, Oregon, and Washington over the past several years. The events are unpopular with customers (electricity is intentionally cut off, sometimes for multiple days) but the alternative — equipment-caused ignitions that could destroy entire communities — is worse. PSPS has driven rapid growth of behind-the-meter solar-plus-storage for resilience, particularly in fire-prone areas. It has also driven utility investment in undergrounding (PG&E has committed to undergrounding 10,000 miles of distribution lines), enhanced weather monitoring, vegetation management programs, and grid hardening. The combination of these investments is gradually reducing PSPS frequency and scope, though the underlying climate and wildfire risk continues to evolve.

What this means for commercial buyers

Three implications for commercial procurement and facility planning. First, geographic risk concentration matters: facilities in ERCOT face winter cold risk, CAISO summer heat risk and PSPS exposure, Gulf Coast hurricane risk, etc. Site selection for new facilities should explicitly factor weather-related grid risk alongside cost. Second, behind-the-meter resilience (microgrids, on-site generation, BTM solar+storage) has shifted from optional to standard for many facility types — particularly data centers, healthcare, manufacturing with continuous processes, and critical commercial facilities. Third, weatherization-related reliability investment is being recovered through utility rate cases, meaning rates in weather-exposed regions are rising to fund hardening programs. For long-term procurement strategy, factoring in trajectory of weather-related rate impact has become a meaningful variable in TCO modeling.