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

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

The day-ahead demand forecast for SPP was off by 4.9% on average (mean absolute percentage error) over 703 hours from 29 September to 28 October 2026, and 62% of hours landed within 5% of the reading. Its bias was +4.1%: it ran high on average, an over forecast. The largest miss was 5,019 MW (17.4%) too high at 16 Oct 2026, 23:00 CDT (UTC-05:00). Dates and times are local (America/Chicago).

Key Facts

  • The day-ahead demand forecast for SPP was off by 4.9% on average (mean absolute percentage error) over 703 hours from 29 September to 28 October 2026, and 62% of hours landed within 5% of the reading. Its bias was +4.1%: it ran high on average, an over forecast. The largest miss was 5,019 MW (17.4%) too high at 16 Oct 2026, 23:00 CDT (UTC-05:00).
  • Across 53 US grids ranked by average error over their own latest 30 day windows, SPP came 32 (1 is the smallest error).
  • On average the forecast differed from reported demand by 1,560 MW, against average demand of 32,442 MW.
  • The forecast was above reported demand in 76% of compared hours.

Forecast Error at a Glance

703 hours from 29 September to 28 October 2026
Average error4.9%
Bias+4.1%
Hours within 5%62%
Worst miss5,019 MW

Average error is the mean absolute percentage gap between the forecast and reported demand. Bias is the signed mean (+1,277 MW per hour on average): the forecast ran high on average, an over forecast. The worst miss was 5,019 MW (17.4%) too high at 16 Oct 2026, 23:00 CDT (UTC-05:00): forecast 33,836 MW, reported 28,817 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)
SPP day-ahead demand forecast and reported demand by hour Hourly reported demand and the day-ahead forecast for SPP 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 10,000 20,000 30,000 40,000 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 SPP 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, 07:0031,371 MW34,690 MW
21 Oct, 08:0031,395 MW34,878 MW
21 Oct, 09:0031,377 MW34,619 MW
21 Oct, 10:0031,611 MW35,034 MW
21 Oct, 11:0032,060 MW35,511 MW
21 Oct, 12:0032,564 MW36,140 MW
21 Oct, 13:0033,144 MW36,945 MW
21 Oct, 14:0033,719 MW37,716 MW
21 Oct, 15:0034,294 MW38,259 MW
21 Oct, 16:0034,906 MW38,572 MW
21 Oct, 17:0034,994 MW38,655 MW
21 Oct, 18:0034,680 MW38,164 MW
21 Oct, 19:0034,438 MW37,497 MW
21 Oct, 20:0033,600 MW36,918 MW
21 Oct, 21:0032,526 MW35,932 MW
21 Oct, 22:0031,015 MW34,599 MW
21 Oct, 23:0029,490 MW33,225 MW
22 Oct, 00:0028,403 MW28,369 MW
22 Oct, 01:0027,716 MW27,705 MW
22 Oct, 02:0027,239 MW27,303 MW
22 Oct, 03:0027,081 MW27,128 MW
22 Oct, 04:0027,318 MW27,364 MW
22 Oct, 05:0028,229 MW28,253 MW
22 Oct, 06:0030,075 MW29,915 MW
22 Oct, 07:0031,349 MW30,915 MW
22 Oct, 08:0031,508 MW31,251 MW
22 Oct, 09:0031,681 MW31,571 MW
22 Oct, 10:0032,133 MW32,183 MW
22 Oct, 11:0032,672 MW32,775 MW
22 Oct, 12:0033,393 MW33,587 MW
22 Oct, 13:0034,363 MW34,525 MW
22 Oct, 14:0035,104 MW35,264 MW
22 Oct, 15:0035,718 MW35,812 MW
22 Oct, 16:0036,062 MW36,218 MW
22 Oct, 17:0035,847 MW36,175 MW
22 Oct, 18:0035,237 MW35,639 MW
22 Oct, 19:0034,800 MW35,058 MW
22 Oct, 20:0034,025 MW34,317 MW
22 Oct, 21:0032,926 MW33,142 MW
22 Oct, 22:0031,487 MW31,630 MW
22 Oct, 23:0029,945 MW30,074 MW
23 Oct, 00:0028,779 MW28,575 MW
23 Oct, 01:0028,033 MW27,849 MW
23 Oct, 02:0027,614 MW27,393 MW
23 Oct, 03:0027,384 MW27,157 MW
23 Oct, 04:0027,547 MW27,324 MW
23 Oct, 05:0028,364 MW28,143 MW
23 Oct, 06:0030,060 MW29,655 MW
23 Oct, 07:0031,259 MW30,717 MW
23 Oct, 08:0031,474 MW31,122 MW
23 Oct, 09:0031,619 MW31,502 MW
23 Oct, 10:0032,091 MW32,221 MW
23 Oct, 11:0032,733 MW32,896 MW
23 Oct, 12:0033,377 MW33,703 MW
23 Oct, 13:0034,123 MW34,528 MW
23 Oct, 14:0034,747 MW35,154 MW
23 Oct, 15:0035,234 MW35,665 MW
23 Oct, 16:0035,441 MW36,054 MW
23 Oct, 17:0035,204 MW35,936 MW
23 Oct, 18:0034,353 MW35,198 MW
23 Oct, 19:0033,822 MW34,549 MW
23 Oct, 20:0032,934 MW33,565 MW
23 Oct, 21:0032,011 MW32,523 MW
23 Oct, 22:0030,934 MW31,224 MW
23 Oct, 23:0029,645 MW29,839 MW
24 Oct, 00:0028,616 MW31,415 MW
24 Oct, 01:0027,803 MW30,796 MW
24 Oct, 02:0027,287 MW30,376 MW
24 Oct, 03:0026,996 MW30,150 MW
24 Oct, 04:0026,903 MW30,206 MW
24 Oct, 05:0027,238 MW30,522 MW
24 Oct, 06:0027,834 MW31,059 MW
24 Oct, 07:0028,532 MW31,742 MW
24 Oct, 08:0029,117 MW32,190 MW
24 Oct, 09:0029,759 MW32,761 MW
24 Oct, 10:0030,278 MW33,856 MW
24 Oct, 11:0030,972 MW34,664 MW
24 Oct, 12:0031,587 MW35,622 MW
24 Oct, 13:0032,312 MW36,604 MW
24 Oct, 14:0033,007 MW37,472 MW
24 Oct, 15:0033,574 MW38,074 MW
24 Oct, 16:0033,838 MW38,424 MW
24 Oct, 17:0033,654 MW38,251 MW
24 Oct, 18:0033,051 MW37,594 MW
24 Oct, 19:0032,684 MW36,796 MW
24 Oct, 20:0031,903 MW35,961 MW
24 Oct, 21:0031,007 MW35,045 MW
24 Oct, 22:0030,012 MW34,040 MW
24 Oct, 23:0028,929 MW32,840 MW
25 Oct, 00:0028,027 MW27,988 MW
25 Oct, 01:0027,254 MW27,261 MW
25 Oct, 02:0026,708 MW26,808 MW
25 Oct, 03:0026,406 MW26,521 MW
25 Oct, 04:0026,342 MW26,447 MW
25 Oct, 05:0026,473 MW26,631 MW
25 Oct, 06:0026,903 MW27,083 MW
25 Oct, 07:0027,611 MW27,667 MW
25 Oct, 08:0028,282 MW28,360 MW
25 Oct, 09:0028,945 MW29,012 MW
25 Oct, 10:0029,547 MW29,657 MW
25 Oct, 11:0030,314 MW30,394 MW
25 Oct, 12:0031,144 MW31,172 MW
25 Oct, 13:0031,984 MW31,891 MW
25 Oct, 14:0032,599 MW32,539 MW
25 Oct, 15:0033,166 MW33,151 MW
25 Oct, 16:0033,540 MW33,747 MW
25 Oct, 17:0033,595 MW34,072 MW
25 Oct, 18:0033,351 MW33,678 MW
25 Oct, 19:0033,228 MW33,371 MW
25 Oct, 20:0032,409 MW32,703 MW
25 Oct, 21:0031,427 MW31,740 MW
25 Oct, 22:0030,148 MW30,386 MW
25 Oct, 23:0028,814 MW28,951 MW
26 Oct, 00:0027,888 MW28,047 MW
26 Oct, 01:0027,150 MW27,396 MW
26 Oct, 02:0026,819 MW27,062 MW
26 Oct, 03:0026,724 MW26,945 MW
26 Oct, 04:0026,837 MW27,178 MW
26 Oct, 05:0027,786 MW28,153 MW
26 Oct, 06:0029,640 MW29,849 MW
26 Oct, 07:0031,073 MW31,063 MW
26 Oct, 08:0031,428 MW31,411 MW
26 Oct, 09:0031,634 MW31,805 MW
26 Oct, 10:0032,094 MW32,300 MW
26 Oct, 11:0032,698 MW32,763 MW
26 Oct, 12:0033,263 MW33,290 MW
26 Oct, 13:0033,774 MW34,019 MW
26 Oct, 14:0034,073 MW34,426 MW
26 Oct, 15:0034,346 MW34,795 MW
26 Oct, 16:0034,493 MW35,085 MW
26 Oct, 17:0034,280 MW35,110 MW
26 Oct, 18:0034,003 MW34,719 MW
26 Oct, 19:0033,819 MW34,419 MW
26 Oct, 20:0033,034 MW33,692 MW
26 Oct, 21:0031,932 MW32,707 MW
26 Oct, 22:0030,564 MW31,267 MW
26 Oct, 23:0029,201 MW29,705 MW
27 Oct, 00:0028,192 MW28,476 MW
27 Oct, 01:0027,531 MW27,773 MW
27 Oct, 02:0027,165 MW27,361 MW
27 Oct, 03:0027,042 MW27,199 MW
27 Oct, 04:0027,236 MW27,435 MW
27 Oct, 05:0028,132 MW28,343 MW
27 Oct, 06:0029,941 MW30,015 MW
27 Oct, 07:0031,292 MW31,187 MW
27 Oct, 08:0031,484 MW31,470 MW
27 Oct, 09:0031,783 MW31,675 MW
27 Oct, 10:0032,184 MW32,072 MW
27 Oct, 11:0032,587 MW32,445 MW
27 Oct, 12:0032,919 MW32,791 MW
27 Oct, 13:0033,421 MW33,217 MW
27 Oct, 14:0033,785 MW33,520 MW
27 Oct, 15:0034,161 MW33,766 MW
27 Oct, 16:0034,458 MW34,002 MW
27 Oct, 17:0034,454 MW34,032 MW
27 Oct, 18:0034,323 MW33,771 MW
27 Oct, 19:0034,322 MW33,591 MW
27 Oct, 20:0033,577 MW33,088 MW
27 Oct, 21:0032,466 MW32,147 MW
27 Oct, 22:0031,024 MW30,805 MW
27 Oct, 23:0029,598 MW29,388 MW
28 Oct, 00:0028,601 MW28,455 MW
28 Oct, 01:0028,028 MW27,765 MW
28 Oct, 02:0027,588 MW27,359 MW
28 Oct, 03:0027,450 MW27,205 MW
28 Oct, 04:0027,730 MW27,358 MW
28 Oct, 05:0028,681 MW28,190 MW
28 Oct, 06:0030,447 MW29,850 MW

Assumptions

  • Only hours with both a forecast and a positive demand reading count (703 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). SPP Demand Forecast Accuracy: Error, Bias and Worst Miss. https://worldpowermonitor.com/forecast-accuracy/spp/

Plain text

World Power Monitor. SPP 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/

BibTeX 
@misc{wpm_forecast_accuracy_spp_2026,
  title = {{SPP 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/}
}

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