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Data as of 2026-10-28
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Built 2026-10-28 (28 October 2026)

ERCOT Demand Forecast Accuracy: Error, Bias and Worst Miss, 28 September to 28 October 2026

The day-ahead demand forecast for ERCOT was off by 1.5% on average (mean absolute percentage error) over 695 hours from 28 September to 28 October 2026, and 97% of hours landed within 5% of the reading. Its bias was +0.3%: it ran close to balanced on average. The largest miss was 6,529 MW (9.8%) too high at 1 Oct 2026, 16:00 CDT (UTC-05:00). Dates and times are local (America/Chicago).

Key Facts

  • The day-ahead demand forecast for ERCOT was off by 1.5% on average (mean absolute percentage error) over 695 hours from 28 September to 28 October 2026, and 97% of hours landed within 5% of the reading. Its bias was +0.3%: it ran close to balanced on average. The largest miss was 6,529 MW (9.8%) too high at 1 Oct 2026, 16:00 CDT (UTC-05:00).
  • Across 53 US grids ranked by average error over their own latest 30 day windows, ERCOT came 4 (1 is the smallest error).
  • On average the forecast differed from reported demand by 871 MW, against average demand of 57,324 MW.
  • The forecast was above reported demand in 52% of compared hours.

Forecast Error at a Glance

695 hours from 28 September to 28 October 2026
Average error1.5%
Bias+0.3%
Hours within 5%97%
Worst miss6,529 MW

Average error is the mean absolute percentage gap between the forecast and reported demand. Bias is the signed mean (+163 MW per hour on average): the forecast ran close to balanced on average. The worst miss was 6,529 MW (9.8%) too high at 1 Oct 2026, 16:00 CDT (UTC-05:00): forecast 73,252 MW, reported 66,723 MW.

Source: U.S. Energy Information Administration (EIA). (US Government work, public domain) Data as of 2026-10-28. Accuracy is computed by World Power Monitor from the operator's hourly forecast and reported demand.

Forecast and Reported Demand, Last 7 Days

Local time, to 28 Oct 2026, 06:00 CDT (UTC-05:00)
ERCOT day-ahead demand forecast and reported demand by hour Hourly reported demand and the day-ahead forecast for ERCOT over the last 7 days of the window, to 28 Oct 2026, 06:00 CDT (UTC-05:00). Gaps are hours with a missing, zero or implausible report. 0 20,000 40,000 60,000 80,000 21 Oct, 07:0022 Oct, 07:0023 Oct, 07:0024 Oct, 07:0025 Oct, 07:0026 Oct, 07:0027 Oct, 07:00
Hourly reported demand and the day-ahead forecast for ERCOT over the last 7 days of the window, to 28 Oct 2026, 06:00 CDT (UTC-05:00). Gaps are hours with a missing, zero or implausible report.
Data to 2026-10-28
Show the data table (168 rows)
Local hourReported demandDay-ahead forecast
21 Oct, 07:0049,380 MW48,934 MW
21 Oct, 08:0049,406 MW49,044 MW
21 Oct, 09:0050,617 MW50,356 MW
21 Oct, 10:0052,027 MW51,880 MW
21 Oct, 11:0053,678 MW53,425 MW
21 Oct, 12:0055,484 MW55,142 MW
21 Oct, 13:0057,633 MW57,136 MW
21 Oct, 14:0059,681 MW59,095 MW
21 Oct, 15:0061,478 MW60,833 MW
21 Oct, 16:0063,026 MW62,090 MW
21 Oct, 17:0062,732 MW61,907 MW
21 Oct, 18:0061,145 MW60,127 MW
21 Oct, 19:0060,186 MW58,987 MW
21 Oct, 20:0058,470 MW57,749 MW
21 Oct, 21:0056,129 MW55,810 MW
21 Oct, 22:0053,405 MW52,935 MW
21 Oct, 23:0050,291 MW49,875 MW
22 Oct, 00:0047,857 MW47,722 MW
22 Oct, 01:0045,964 MW45,855 MW
22 Oct, 02:0044,768 MW44,566 MW
22 Oct, 03:0044,266 MW43,979 MW
22 Oct, 04:0044,409 MW44,222 MW
22 Oct, 05:0045,772 MW45,620 MW
22 Oct, 06:0048,284 MW48,086 MW
22 Oct, 07:0049,448 MW49,298 MW
22 Oct, 08:0049,766 MW49,591 MW
22 Oct, 09:0051,387 MW51,115 MW
22 Oct, 10:0052,864 MW52,981 MW
22 Oct, 11:0054,555 MW54,948 MW
22 Oct, 12:0056,339 MW57,005 MW
22 Oct, 13:0058,280 MW59,446 MW
22 Oct, 14:0060,211 MW61,655 MW
22 Oct, 15:0062,151 MW63,474 MW
22 Oct, 16:0063,398 MW64,515 MW
22 Oct, 17:0063,087 MW64,053 MW
22 Oct, 18:0061,155 MW61,929 MW
22 Oct, 19:0059,731 MW60,683 MW
22 Oct, 20:0058,034 MW59,233 MW
22 Oct, 21:0056,025 MW57,159 MW
22 Oct, 22:0053,159 MW54,101 MW
22 Oct, 23:0050,083 MW50,934 MW
23 Oct, 00:0047,613 MW48,486 MW
23 Oct, 01:0045,845 MW46,449 MW
23 Oct, 02:0044,813 MW45,050 MW
23 Oct, 03:0044,215 MW44,433 MW
23 Oct, 04:0044,421 MW44,655 MW
23 Oct, 05:0045,545 MW45,892 MW
23 Oct, 06:0047,866 MW48,159 MW
23 Oct, 07:0048,727 MW49,442 MW
23 Oct, 08:0049,252 MW49,847 MW
23 Oct, 09:0050,948 MW51,550 MW
23 Oct, 10:0052,458 MW53,460 MW
23 Oct, 11:0054,313 MW55,422 MW
23 Oct, 12:0056,230 MW57,563 MW
23 Oct, 13:0058,642 MW60,013 MW
23 Oct, 14:0060,848 MW62,277 MW
23 Oct, 15:0062,803 MW63,846 MW
23 Oct, 16:0063,956 MW64,700 MW
23 Oct, 17:0063,475 MW64,070 MW
23 Oct, 18:0061,261 MW61,673 MW
23 Oct, 19:0059,591 MW60,033 MW
23 Oct, 20:0057,748 MW58,397 MW
23 Oct, 21:0055,909 MW56,350 MW
23 Oct, 22:0053,647 MW54,024 MW
23 Oct, 23:0051,105 MW51,373 MW
24 Oct, 00:0048,692 MW48,875 MW
24 Oct, 01:0046,734 MW46,899 MW
24 Oct, 02:0045,322 MW45,488 MW
24 Oct, 03:0044,474 MW44,590 MW
24 Oct, 04:0044,116 MW44,230 MW
24 Oct, 05:0044,386 MW44,499 MW
24 Oct, 06:0045,189 MW45,416 MW
24 Oct, 07:0046,271 MW46,293 MW
24 Oct, 08:0047,568 MW47,424 MW
24 Oct, 09:0049,463 MW49,698 MW
24 Oct, 10:0051,609 MW51,953 MW
24 Oct, 11:0053,770 MW54,104 MW
24 Oct, 12:0055,830 MW56,214 MW
24 Oct, 13:0057,893 MW58,360 MW
24 Oct, 14:0059,779 MW60,355 MW
24 Oct, 15:0061,388 MW62,106 MW
24 Oct, 16:0062,094 MW63,023 MW
24 Oct, 17:0061,625 MW62,708 MW
24 Oct, 18:0059,911 MW60,730 MW
24 Oct, 19:0058,813 MW59,464 MW
24 Oct, 20:0057,416 MW57,885 MW
24 Oct, 21:0055,830 MW55,900 MW
24 Oct, 22:0053,873 MW53,664 MW
24 Oct, 23:0051,692 MW51,149 MW
25 Oct, 00:0049,473 MW48,837 MW
25 Oct, 01:0047,510 MW46,892 MW
25 Oct, 02:0046,042 MW45,575 MW
25 Oct, 03:0045,064 MW44,675 MW
25 Oct, 04:0044,772 MW44,192 MW
25 Oct, 05:0044,674 MW44,224 MW
25 Oct, 06:0045,199 MW44,743 MW
25 Oct, 07:0045,730 MW45,318 MW
25 Oct, 08:0046,770 MW46,437 MW
25 Oct, 09:0048,526 MW48,586 MW
25 Oct, 10:0050,584 MW50,658 MW
25 Oct, 11:0052,689 MW52,616 MW
25 Oct, 12:0054,594 MW54,498 MW
25 Oct, 13:0056,326 MW56,266 MW
25 Oct, 14:0057,698 MW57,918 MW
25 Oct, 15:0058,296 MW59,306 MW
25 Oct, 16:0058,266 MW60,112 MW
25 Oct, 17:0057,642 MW59,999 MW
25 Oct, 18:0057,230 MW58,486 MW
25 Oct, 19:0057,506 MW58,067 MW
25 Oct, 20:0056,549 MW57,049 MW
25 Oct, 21:0054,832 MW55,394 MW
25 Oct, 22:0052,263 MW52,897 MW
25 Oct, 23:0049,476 MW50,027 MW
26 Oct, 00:0047,330 MW47,956 MW
26 Oct, 01:0045,696 MW46,169 MW
26 Oct, 02:0044,756 MW45,021 MW
26 Oct, 03:0044,208 MW44,536 MW
26 Oct, 04:0044,434 MW44,955 MW
26 Oct, 05:0045,622 MW46,397 MW
26 Oct, 06:0048,175 MW48,882 MW
26 Oct, 07:0048,966 MW50,287 MW
26 Oct, 08:0048,867 MW50,578 MW
26 Oct, 09:0050,147 MW51,900 MW
26 Oct, 10:0051,681 MW53,551 MW
26 Oct, 11:0053,510 MW55,129 MW
26 Oct, 12:0055,344 MW56,693 MW
26 Oct, 13:0057,075 MW58,440 MW
26 Oct, 14:0058,655 MW60,110 MW
26 Oct, 15:0059,715 MW61,405 MW
26 Oct, 16:0060,001 MW62,083 MW
26 Oct, 17:0059,364 MW61,648 MW
26 Oct, 18:0058,255 MW59,991 MW
26 Oct, 19:0058,393 MW59,637 MW
26 Oct, 20:0057,034 MW58,908 MW
26 Oct, 21:0054,525 MW56,966 MW
26 Oct, 22:0051,615 MW54,261 MW
26 Oct, 23:0049,509 MW51,341 MW
27 Oct, 00:0047,276 MW48,348 MW
27 Oct, 01:0045,576 MW46,476 MW
27 Oct, 02:0044,607 MW45,198 MW
27 Oct, 03:0044,316 MW44,567 MW
27 Oct, 04:0044,667 MW44,913 MW
27 Oct, 05:0046,073 MW46,704 MW
27 Oct, 06:0048,486 MW49,491 MW
27 Oct, 07:0049,632 MW50,824 MW
27 Oct, 08:0049,852 MW50,831 MW
27 Oct, 09:0051,179 MW51,969 MW
27 Oct, 10:0052,593 MW53,345 MW
27 Oct, 11:0054,204 MW54,758 MW
27 Oct, 12:0055,851 MW56,153 MW
27 Oct, 13:0057,560 MW57,570 MW
27 Oct, 14:0058,988 MW58,582 MW
27 Oct, 15:0060,273 MW59,316 MW
27 Oct, 16:0061,075 MW59,848 MW
27 Oct, 17:0060,793 MW59,491 MW
27 Oct, 18:0059,772 MW58,188 MW
27 Oct, 19:0059,283 MW57,978 MW
27 Oct, 20:0058,308 MW57,281 MW
27 Oct, 21:0056,837 MW55,520 MW
27 Oct, 22:0054,140 MW53,151 MW
27 Oct, 23:0051,403 MW50,588 MW
28 Oct, 00:0049,195 MW48,708 MW
28 Oct, 01:0047,282 MW46,924 MW
28 Oct, 02:0046,079 MW45,813 MW
28 Oct, 03:0045,336 MW45,124 MW
28 Oct, 04:0045,856 MW45,305 MW
28 Oct, 05:0047,390 MW46,884 MW
28 Oct, 06:0049,943 MW49,430 MW

Assumptions

  • Only hours with both a forecast and a positive demand reading count (695 of 720 hours in the window). Missing and zero values, and readings under 30% or over 3 times the grid's own median for the window, are treated as reporting faults and left out.
  • Error is (forecast minus reported demand) divided by reported demand; average error uses absolute values so high and low misses do not cancel. Bias keeps the sign and does cancel.
  • Reported demand is preliminary and may be revised. A 30 day window is a short sample and one heat wave or holiday can move these figures.
  • US figures are for the EIA balancing authority or region named on this page. US and European grids are ranked separately.
Cite this page
APA 7

World Power Monitor. (2026). ERCOT Demand Forecast Accuracy: Error, Bias and Worst Miss. https://worldpowermonitor.com/forecast-accuracy/ercot/

Plain text

World Power Monitor. ERCOT Demand Forecast Accuracy: Error, Bias and Worst Miss. Data as of 2026-10-28. Data from U.S. Energy Information Administration. https://worldpowermonitor.com/forecast-accuracy/ercot/

BibTeX 
@misc{wpm_forecast_accuracy_ercot_2026,
  title = {{ERCOT Demand Forecast Accuracy: Error, Bias and Worst Miss}},
  author = {{World Power Monitor}},
  year = {2026},
  note = {Data as of 2026-10-28. Data from U.S. Energy Information Administration.},
  url = {https://worldpowermonitor.com/forecast-accuracy/ercot/}
}

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