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

SWPW Demand Forecast Accuracy: Error, Bias and Worst Miss, 29 September to 28 October 2026

The day-ahead demand forecast for SWPW was off by 10.8% on average (mean absolute percentage error) over 689 hours from 29 September to 28 October 2026, and 63% of hours landed within 5% of the reading. Its bias was +10.1%: it ran high on average, an over forecast. The largest miss was 1,043 MW (38.7%) too high at 2 Oct 2026, 15:00 CDT (UTC-05:00). Dates and times are local (America/Chicago).

Key Facts

  • The day-ahead demand forecast for SWPW was off by 10.8% on average (mean absolute percentage error) over 689 hours from 29 September to 28 October 2026, and 63% of hours landed within 5% of the reading. Its bias was +10.1%: it ran high on average, an over forecast. The largest miss was 1,043 MW (38.7%) too high at 2 Oct 2026, 15:00 CDT (UTC-05:00).
  • Across 53 US grids ranked by average error over their own latest 30 day windows, SWPW came 44 (1 is the smallest error).
  • On average the forecast differed from reported demand by 289 MW, against average demand of 2,681 MW.
  • The forecast was above reported demand in 78% of compared hours.

Forecast Error at a Glance

689 hours from 29 September to 28 October 2026
Average error10.8%
Bias+10.1%
Hours within 5%63%
Worst miss1,043 MW

Average error is the mean absolute percentage gap between the forecast and reported demand. Bias is the signed mean (+269 MW per hour on average): the forecast ran high on average, an over forecast. The worst miss was 1,043 MW (38.7%) too high at 2 Oct 2026, 15:00 CDT (UTC-05:00): forecast 3,741 MW, reported 2,698 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)
SWPW day-ahead demand forecast and reported demand by hour Hourly reported demand and the day-ahead forecast for SWPW 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 1,000 2,000 3,000 4,000 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 SWPW 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, 07:002,693 MW3,335 MW
21 Oct, 08:002,782 MW3,423 MW
21 Oct, 09:002,733 MW3,345 MW
21 Oct, 10:002,688 MW3,375 MW
21 Oct, 11:002,703 MW3,436 MW
21 Oct, 12:002,710 MW3,425 MW
21 Oct, 13:002,713 MW3,470 MW
21 Oct, 14:002,751 MW3,431 MW
21 Oct, 15:002,824 MW3,490 MW
21 Oct, 16:002,865 MW3,561 MW
21 Oct, 17:002,903 MW3,631 MW
21 Oct, 18:002,938 MW3,667 MW
21 Oct, 19:002,995 MW3,726 MW
21 Oct, 20:002,969 MW3,715 MW
21 Oct, 21:002,891 MW3,656 MW
21 Oct, 22:002,807 MW3,550 MW
21 Oct, 23:002,681 MW3,413 MW
22 Oct, 00:002,549 MW2,531 MW
22 Oct, 01:002,447 MW2,449 MW
22 Oct, 02:002,387 MW2,391 MW
22 Oct, 03:002,359 MW2,356 MW
22 Oct, 04:002,347 MW2,341 MW
22 Oct, 05:002,367 MW2,378 MW
22 Oct, 06:002,456 MW2,473 MW
22 Oct, 07:002,627 MW2,645 MW
22 Oct, 08:002,737 MW2,736 MW
22 Oct, 09:002,778 MW2,699 MW
22 Oct, 10:002,808 MW2,647 MW
22 Oct, 11:002,820 MW2,651 MW
22 Oct, 12:002,821 MW2,677 MW
22 Oct, 13:002,823 MW2,698 MW
22 Oct, 14:002,790 MW2,755 MW
22 Oct, 15:002,807 MW2,792 MW
22 Oct, 16:002,840 MW2,761 MW
22 Oct, 17:002,894 MW2,823 MW
22 Oct, 18:002,928 MW2,891 MW
22 Oct, 19:002,954 MW2,977 MW
22 Oct, 20:002,922 MW2,962 MW
22 Oct, 21:002,853 MW2,894 MW
22 Oct, 22:002,763 MW2,799 MW
22 Oct, 23:002,639 MW2,664 MW
23 Oct, 00:002,520 MW2,565 MW
23 Oct, 01:002,454 MW2,487 MW
23 Oct, 02:002,400 MW2,439 MW
23 Oct, 03:002,363 MW2,408 MW
23 Oct, 04:002,368 MW2,390 MW
23 Oct, 05:002,393 MW2,426 MW
23 Oct, 06:002,487 MW2,513 MW
23 Oct, 07:002,644 MW2,701 MW
23 Oct, 08:002,763 MW2,796 MW
23 Oct, 09:002,748 MW2,763 MW
23 Oct, 10:002,670 MW2,722 MW
23 Oct, 11:002,669 MW2,731 MW
23 Oct, 12:002,674 MW2,762 MW
23 Oct, 13:002,685 MW2,787 MW
23 Oct, 14:002,716 MW2,786 MW
23 Oct, 15:002,759 MW2,843 MW
23 Oct, 16:002,813 MW2,817 MW
23 Oct, 17:002,867 MW2,868 MW
23 Oct, 18:002,929 MW2,912 MW
23 Oct, 19:002,963 MW2,974 MW
23 Oct, 20:002,921 MW2,932 MW
23 Oct, 21:002,840 MW2,844 MW
23 Oct, 22:002,780 MW2,783 MW
23 Oct, 23:002,676 MW2,686 MW
24 Oct, 00:002,565 MW3,194 MW
24 Oct, 01:002,463 MW3,117 MW
24 Oct, 02:002,393 MW3,064 MW
24 Oct, 03:002,356 MW3,028 MW
24 Oct, 04:002,340 MW3,018 MW
24 Oct, 05:002,347 MW3,075 MW
24 Oct, 06:002,393 MW3,176 MW
24 Oct, 07:002,479 MW3,250 MW
24 Oct, 08:002,559 MW3,300 MW
24 Oct, 09:002,602 MW3,319 MW
24 Oct, 10:002,621 MW3,349 MW
24 Oct, 11:002,663 MW3,323 MW
24 Oct, 12:002,602 MW3,340 MW
24 Oct, 13:002,565 MW3,336 MW
24 Oct, 14:002,602 MW3,314 MW
24 Oct, 15:002,634 MW3,346 MW
24 Oct, 16:002,674 MW3,308 MW
24 Oct, 17:002,750 MW3,391 MW
24 Oct, 18:002,810 MW3,493 MW
24 Oct, 19:002,864 MW3,565 MW
24 Oct, 20:002,854 MW3,572 MW
24 Oct, 21:002,802 MW3,534 MW
24 Oct, 22:002,749 MW3,459 MW
24 Oct, 23:002,655 MW3,384 MW
25 Oct, 00:002,564 MW2,621 MW
25 Oct, 01:002,479 MW2,530 MW
25 Oct, 02:002,423 MW2,472 MW
25 Oct, 03:002,386 MW2,439 MW
25 Oct, 04:002,380 MW2,435 MW
25 Oct, 05:002,390 MW2,446 MW
25 Oct, 06:002,429 MW2,478 MW
25 Oct, 07:002,501 MW2,545 MW
25 Oct, 08:002,594 MW2,610 MW
25 Oct, 09:002,638 MW2,620 MW
25 Oct, 10:002,647 MW2,582 MW
25 Oct, 11:002,624 MW2,570 MW
25 Oct, 12:002,600 MW2,595 MW
25 Oct, 13:002,584 MW2,602 MW
25 Oct, 14:002,578 MW2,632 MW
25 Oct, 15:002,590 MW2,662 MW
25 Oct, 16:002,625 MW2,644 MW
25 Oct, 17:002,675 MW2,745 MW
25 Oct, 18:002,783 MW2,866 MW
25 Oct, 19:002,896 MW2,971 MW
25 Oct, 20:002,892 MW2,979 MW
25 Oct, 21:002,832 MW2,931 MW
25 Oct, 22:002,748 MW2,838 MW
25 Oct, 23:002,627 MW2,715 MW
26 Oct, 00:002,510 MW2,626 MW
26 Oct, 01:002,438 MW2,533 MW
26 Oct, 02:002,400 MW2,480 MW
26 Oct, 03:002,381 MW2,445 MW
26 Oct, 04:002,386 MW2,439 MW
26 Oct, 05:002,434 MW2,466 MW
26 Oct, 06:002,547 MW2,577 MW
26 Oct, 07:002,719 MW2,760 MW
26 Oct, 08:002,799 MW2,856 MW
26 Oct, 09:002,781 MW2,837 MW
26 Oct, 10:002,757 MW2,773 MW
26 Oct, 11:002,726 MW2,748 MW
26 Oct, 12:002,692 MW2,730 MW
26 Oct, 13:002,650 MW2,701 MW
26 Oct, 14:002,617 MW2,720 MW
26 Oct, 15:002,595 MW2,737 MW
26 Oct, 16:002,606 MW2,689 MW
26 Oct, 17:002,684 MW2,757 MW
26 Oct, 18:002,805 MW2,839 MW
26 Oct, 19:002,923 MW2,953 MW
26 Oct, 20:002,918 MW2,958 MW
26 Oct, 21:002,864 MW2,916 MW
26 Oct, 22:002,782 MW2,840 MW
26 Oct, 23:002,658 MW2,719 MW
27 Oct, 00:002,547 MW2,609 MW
27 Oct, 01:002,475 MW2,509 MW
27 Oct, 02:002,440 MW2,465 MW
27 Oct, 03:002,430 MW2,435 MW
27 Oct, 04:002,440 MW2,432 MW
27 Oct, 05:002,487 MW2,462 MW
27 Oct, 06:002,603 MW2,575 MW
27 Oct, 07:002,792 MW2,751 MW
27 Oct, 08:002,895 MW2,836 MW
27 Oct, 09:002,859 MW2,803 MW
27 Oct, 10:002,780 MW2,744 MW
27 Oct, 11:002,703 MW2,732 MW
27 Oct, 12:002,670 MW2,723 MW
27 Oct, 13:002,635 MW2,697 MW
27 Oct, 14:002,615 MW2,726 MW
27 Oct, 15:002,605 MW2,738 MW
27 Oct, 16:002,609 MW2,677 MW
27 Oct, 17:002,686 MW2,728 MW
27 Oct, 18:002,807 MW2,796 MW
27 Oct, 19:002,901 MW2,913 MW
27 Oct, 20:002,887 MW2,924 MW
27 Oct, 21:002,831 MW2,874 MW
27 Oct, 22:002,756 MW2,796 MW
27 Oct, 23:002,645 MW2,668 MW
28 Oct, 00:002,529 MW2,561 MW
28 Oct, 01:002,470 MW2,473 MW
28 Oct, 02:002,432 MW2,430 MW
28 Oct, 03:002,413 MW2,407 MW
28 Oct, 04:002,417 MW2,401 MW
28 Oct, 05:002,492 MW2,447 MW
28 Oct, 06:002,615 MW2,556 MW

Assumptions

  • Only hours with both a forecast and a positive demand reading count (689 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). SWPW Demand Forecast Accuracy: Error, Bias and Worst Miss. https://worldpowermonitor.com/forecast-accuracy/spp-west/

Plain text

World Power Monitor. SWPW 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/spp-west/

BibTeX 
@misc{wpm_forecast_accuracy_spp_west_2026,
  title = {{SWPW 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/spp-west/}
}

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