Question 1

What does the ERCOT footprint cover?

Accepted Answer

The Electric Reliability Council of Texas manages roughly 90% of the state's electric load across 254 counties. Notably outside the ERCOT footprint are far West Texas (which sits in the Western Interconnection), parts of the Panhandle and East Texas (which sit in the Eastern Interconnection), and a handful of municipal utilities. ERCOT is unique among major U.S. grids in operating as an electrical island — only a small set of DC ties to the Southwest Power Pool and Mexico connect it to neighboring grids — which means it cannot easily import emergency power during a crisis, as Winter Storm Uri made painfully clear in February 2021.

Question 2

What does the Texas generation mix look like?

Accepted Answer

ERCOT runs the largest installed wind fleet of any U.S. system, with most of the capacity concentrated in West Texas and the Panhandle along the Caprock Escarpment, plus a growing build-out of South Texas wind near the coast. Utility-scale solar has grown explosively in the past several years, particularly in West and Central Texas. Natural gas combined-cycle and peaker fleets remain the dispatchable backbone, with two large nuclear units at Comanche Peak and South Texas Project providing baseload. Battery storage is now scaling rapidly. Congestion on the West-to-load transmission corridors remains a chronic constraint.

Question 3

What weather events most stress the ERCOT grid?

Accepted Answer

Two opposite stress regimes define ERCOT operations. The summer challenge is extreme heat — record air conditioning demand across Dallas–Fort Worth, Houston, San Antonio, and Austin pushes the system to lean on solar and wind output for daytime peaks while preserving thermal capacity for the post-sunset evening ramp. The winter challenge is the opposite — Arctic cold snaps push gas wellhead production into freeze-offs at the same moment they spike heating demand. Hurricanes drive multi-day load loss across the eastern half of the footprint (Harvey 2017, Ike 2008, Beryl 2024), and spring severe weather brings tornadoes and large hail that damages solar facilities.

Question 4

What kinds of NWS alerts dominate Texas summers?

Accepted Answer

Summer in the Texas metros is defined by Heat Advisories and Excessive Heat Warnings issued when forecast heat indices exceed 105°F (Advisory) or 110°F (Warning) for two or more hours, criteria that are routinely met across Houston, Dallas–Fort Worth, San Antonio, and Austin from late June into September. The metros along the Gulf Coast see additional Coastal Flood Statements during onshore-flow events, and the Hill Country and South Texas plains can pick up Severe Thunderstorm Warnings and Tornado Warnings on most active afternoons.

Question 5

How does the National Hurricane Center's outlook affect Texas?

Accepted Answer

The National Hurricane Center publishes Tropical Weather Outlooks every six hours during hurricane season (June 1 through November 30) covering the Atlantic and Gulf basins. Once a system poses a credible threat to the Texas coast, the NHC issues Hurricane Watches (within 48 hours of expected onset) and Hurricane Warnings (within 36 hours), typically followed by Storm Surge Warnings for the coastal counties. Major Texas landfalls — Harvey in 2017, Ike in 2008, Beryl in 2024 — drove multi-day load loss across the eastern half of the footprint and prolonged restoration in the most damaged areas.

Question 6

What weather drives Arctic outbreaks across Texas?

Accepted Answer

When the polar vortex weakens or dislocates, modified Arctic air can sweep south across the Plains and reach all the way to the Rio Grande Valley. These events are forecast 5 to 10 days in advance through Climate Prediction Center 6–10 day outlooks and downstream Winter Storm Watches, then Winter Storm Warnings and Wind Chill Warnings as the airmass approaches. The February 2021 Winter Storm Uri event remains the benchmark — sustained sub-freezing temperatures across the entire state for nearly a week, with overnight lows in the single digits across the Hill Country and DFW.

Question 7

Why is severe weather a year-round concern for the Texas grid?

Accepted Answer

North and Central Texas sit at the southern end of Tornado Alley, with peak tornado season from late March through May but secondary peaks in October and November. Storm Prediction Center convective outlooks (Marginal through High Risk) flag days when supercells are likely, and Tornado Watches and Severe Thunderstorm Watches typically precede individual storms by hours. Large hail (1.75 inch and up) is a particular concern for the rapidly growing utility-scale solar fleet across West and Central Texas.

Question 8

How are coastal Texas storm surge alerts issued?

Accepted Answer

Storm Surge Watches and Storm Surge Warnings are issued by the National Hurricane Center for the coastal counties along the western Gulf when life-threatening inundation from a tropical system is possible (Watch, within 48 hours) or expected (Warning, within 36 hours). Surge forecasts are accompanied by inundation maps that estimate water heights above ground level. The Galveston-Houston region, the Coastal Bend, and the Lower Texas Coast each have distinct surge histories that inform pre-storm staging and evacuation decisions.

Question 9

What sources are referenced for the historical events on this page?

Accepted Answer

Specific event references on this page (the February 2021 Winter Storm Uri event, Hurricanes Harvey 2017, Ike 2008, and Beryl 2024) are drawn from the FERC, NERC, and Regional Entity Joint Inquiry into the February 2021 Cold Weather Event, ERCOT's published event reports and market notices at ercot.com, the National Hurricane Center's Tropical Cyclone Reports at nhc.noaa.gov, and NWS event summaries. NWS heat-index criteria are documented in the relevant NWS forecast office Weather-Ready Nation pages.

Metric	Actual	Normal	Departure
CDD	1690.0	1185.3	+504.7
HDD	752.9	1151.9	-399.0

ERCOT

Temperature Forecast

Precipitation Chance

Recent History (7 days)

ERCOT — Frequently Asked Questions