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

The day-ahead demand forecast for PJM was off by 3.0% on average (mean absolute percentage error) over 719 hours from 28 September to 28 October 2026, and 84% of hours landed within 5% of the reading. Its bias was -1.1%: it ran low on average, an under forecast. The largest miss was 7,621 MW (9.2%) too high at 19 Oct 2026, 05:00 EDT (UTC-04:00). Dates and times are local (America/New_York).

Key Facts

The day-ahead demand forecast for PJM was off by 3.0% on average (mean absolute percentage error) over 719 hours from 28 September to 28 October 2026, and 84% of hours landed within 5% of the reading. Its bias was -1.1%: it ran low on average, an under forecast. The largest miss was 7,621 MW (9.2%) too high at 19 Oct 2026, 05:00 EDT (UTC-04:00).
Across 53 US grids ranked by average error over their own latest 30 day windows, PJM came 17 (1 is the smallest error).
On average the forecast differed from reported demand by 2,588 MW, against average demand of 86,957 MW.
The forecast was above reported demand in 35% of compared hours.

Forecast Error at a Glance

719 hours from 28 September to 28 October 2026

Average error3.0%

Bias-1.1%

Hours within 5%84%

Worst miss7,621 MW

Average error is the mean absolute percentage gap between the forecast and reported demand. Bias is the signed mean (-936 MW per hour on average): the forecast ran low on average, an under forecast. The worst miss was 7,621 MW (9.2%) too high at 19 Oct 2026, 05:00 EDT (UTC-04:00): forecast 90,333 MW, reported 82,712 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, 07:00 EDT (UTC-04:00)

Hourly reported demand and the day-ahead forecast for PJM over the last 7 days of the window, to 28 Oct 2026, 07:00 EDT (UTC-04:00). Gaps are hours with a missing, zero or implausible report.

Data to 2026-10-28

Show the data table (168 rows)

Local hour	Reported demand	Day-ahead forecast
21 Oct, 08:00	92,120 MW	88,107 MW
21 Oct, 09:00	89,125 MW	86,273 MW
21 Oct, 10:00	88,048 MW	84,786 MW
21 Oct, 11:00	87,793 MW	84,124 MW
21 Oct, 12:00	86,763 MW	84,011 MW
21 Oct, 13:00	86,536 MW	84,071 MW
21 Oct, 14:00	86,984 MW	84,729 MW
21 Oct, 15:00	87,334 MW	86,466 MW
21 Oct, 16:00	88,662 MW	88,941 MW
21 Oct, 17:00	90,584 MW	90,258 MW
21 Oct, 18:00	92,494 MW	91,728 MW
21 Oct, 19:00	93,776 MW	91,409 MW
21 Oct, 20:00	92,348 MW	89,002 MW
21 Oct, 21:00	89,336 MW	85,060 MW
21 Oct, 22:00	85,367 MW	81,181 MW
21 Oct, 23:00	81,831 MW	78,047 MW
22 Oct, 00:00	80,151 MW	76,208 MW
22 Oct, 01:00	79,754 MW	75,538 MW
22 Oct, 02:00	78,958 MW	75,536 MW
22 Oct, 03:00	79,082 MW	77,238 MW
22 Oct, 04:00	79,768 MW	81,500 MW
22 Oct, 05:00	82,992 MW	88,226 MW
22 Oct, 06:00	89,269 MW	92,238 MW
22 Oct, 07:00	93,956 MW	91,491 MW
22 Oct, 08:00	93,500 MW	88,748 MW
22 Oct, 09:00	90,297 MW	86,663 MW
22 Oct, 10:00	88,526 MW	85,285 MW
22 Oct, 11:00	88,441 MW	84,472 MW
22 Oct, 12:00	87,998 MW	84,485 MW
22 Oct, 13:00	87,898 MW	84,563 MW
22 Oct, 14:00	87,870 MW	85,115 MW
22 Oct, 15:00	88,572 MW	86,712 MW
22 Oct, 16:00	89,379 MW	88,928 MW
22 Oct, 17:00	91,119 MW	90,293 MW
22 Oct, 18:00	92,921 MW	91,488 MW
22 Oct, 19:00	93,737 MW	91,241 MW
22 Oct, 20:00	92,420 MW	88,843 MW
22 Oct, 21:00	89,498 MW	84,824 MW
22 Oct, 22:00	86,226 MW	80,800 MW
22 Oct, 23:00	83,316 MW	77,568 MW
23 Oct, 00:00	80,520 MW	75,900 MW
23 Oct, 01:00	78,741 MW	75,029 MW
23 Oct, 02:00	77,767 MW	74,892 MW
23 Oct, 03:00	77,247 MW	76,203 MW
23 Oct, 04:00	78,404 MW	80,093 MW
23 Oct, 05:00	81,549 MW	86,422 MW
23 Oct, 06:00	87,511 MW	90,598 MW
23 Oct, 07:00	91,912 MW	90,595 MW
23 Oct, 08:00	91,934 MW	88,862 MW
23 Oct, 09:00	89,478 MW	87,263 MW
23 Oct, 10:00	88,505 MW	86,013 MW
23 Oct, 11:00	88,553 MW	85,320 MW
23 Oct, 12:00	87,764 MW	85,000 MW
23 Oct, 13:00	87,258 MW	84,932 MW
23 Oct, 14:00	87,307 MW	85,212 MW
23 Oct, 15:00	87,886 MW	86,571 MW
23 Oct, 16:00	87,805 MW	88,419 MW
23 Oct, 17:00	89,063 MW	89,078 MW
23 Oct, 18:00	90,232 MW	89,892 MW
23 Oct, 19:00	90,603 MW	89,377 MW
23 Oct, 20:00	89,374 MW	87,279 MW
23 Oct, 21:00	87,293 MW	84,272 MW
23 Oct, 22:00	84,625 MW	80,770 MW
23 Oct, 23:00	81,286 MW	77,862 MW
24 Oct, 00:00	78,938 MW	75,580 MW
24 Oct, 01:00	77,336 MW	74,613 MW
24 Oct, 02:00	76,402 MW	74,230 MW
24 Oct, 03:00	76,276 MW	74,736 MW
24 Oct, 04:00	76,969 MW	76,547 MW
24 Oct, 05:00	78,558 MW	79,359 MW
24 Oct, 06:00	81,189 MW	81,849 MW
24 Oct, 07:00	84,575 MW	82,583 MW
24 Oct, 08:00	85,981 MW	81,668 MW
24 Oct, 09:00	85,906 MW	80,310 MW
24 Oct, 10:00	85,535 MW	79,127 MW
24 Oct, 11:00	83,882 MW	78,086 MW
24 Oct, 12:00	82,834 MW	77,357 MW
24 Oct, 13:00	81,852 MW	77,134 MW
24 Oct, 14:00	81,780 MW	77,647 MW
24 Oct, 15:00	82,368 MW	79,387 MW
24 Oct, 16:00	82,718 MW	81,753 MW
24 Oct, 17:00	84,058 MW	83,185 MW
24 Oct, 18:00	86,038 MW	84,806 MW
24 Oct, 19:00	87,063 MW	84,831 MW
24 Oct, 20:00	86,076 MW	83,290 MW
24 Oct, 21:00	84,499 MW	80,819 MW
24 Oct, 22:00	82,059 MW	77,939 MW
24 Oct, 23:00	79,779 MW	75,576 MW
25 Oct, 00:00	77,794 MW	73,944 MW
25 Oct, 01:00	76,216 MW	73,131 MW
25 Oct, 02:00	75,496 MW	72,767 MW
25 Oct, 03:00	75,913 MW	73,270 MW
25 Oct, 04:00	76,552 MW	74,849 MW
25 Oct, 05:00	77,009 MW	77,313 MW
25 Oct, 06:00	78,578 MW	79,424 MW
25 Oct, 07:00	81,395 MW	80,161 MW
25 Oct, 08:00	82,733 MW	79,242 MW
25 Oct, 09:00	82,883 MW	77,984 MW
25 Oct, 10:00	82,163 MW	77,332 MW
25 Oct, 11:00	81,166 MW	77,010 MW
25 Oct, 12:00	80,918 MW	76,919 MW
25 Oct, 13:00	80,847 MW	77,137 MW
25 Oct, 14:00	81,591 MW	78,227 MW
25 Oct, 15:00	82,737 MW	80,598 MW
25 Oct, 16:00	83,725 MW	83,762 MW
25 Oct, 17:00	85,814 MW	85,706 MW
25 Oct, 18:00	88,272 MW	87,601 MW
25 Oct, 19:00	89,917 MW	87,415 MW
25 Oct, 20:00	88,614 MW	85,059 MW
25 Oct, 21:00	86,010 MW	81,955 MW
25 Oct, 22:00	82,590 MW	78,717 MW
25 Oct, 23:00	80,512 MW	76,473 MW
26 Oct, 00:00	79,130 MW	75,208 MW
26 Oct, 01:00	77,770 MW	74,760 MW
26 Oct, 02:00	77,369 MW	74,938 MW
26 Oct, 03:00	77,730 MW	76,865 MW
26 Oct, 04:00	79,243 MW	81,451 MW
26 Oct, 05:00	82,456 MW	88,899 MW
26 Oct, 06:00	88,719 MW	93,204 MW
26 Oct, 07:00	93,593 MW	92,409 MW
26 Oct, 08:00	93,636 MW	89,527 MW
26 Oct, 09:00	91,278 MW	87,540 MW
26 Oct, 10:00	89,651 MW	86,239 MW
26 Oct, 11:00	89,634 MW	85,708 MW
26 Oct, 12:00	89,392 MW	85,761 MW
26 Oct, 13:00	89,512 MW	85,935 MW
26 Oct, 14:00	89,805 MW	86,612 MW
26 Oct, 15:00	90,069 MW	88,356 MW
26 Oct, 16:00	90,518 MW	90,866 MW
26 Oct, 17:00	92,591 MW	92,317 MW
26 Oct, 18:00	94,169 MW	93,734 MW
26 Oct, 19:00	94,460 MW	92,919 MW
26 Oct, 20:00	92,490 MW	89,612 MW
26 Oct, 21:00	89,484 MW	85,271 MW
26 Oct, 22:00	85,381 MW	81,124 MW
26 Oct, 23:00	82,054 MW	77,824 MW
27 Oct, 00:00	80,152 MW	75,911 MW
27 Oct, 01:00	78,764 MW	74,808 MW
27 Oct, 02:00	78,269 MW	74,563 MW
27 Oct, 03:00	77,824 MW	75,861 MW
27 Oct, 04:00	79,026 MW	79,742 MW
27 Oct, 05:00	80,931 MW	86,253 MW
27 Oct, 06:00	87,348 MW	90,489 MW
27 Oct, 07:00	91,751 MW	90,564 MW
27 Oct, 08:00	91,876 MW	88,651 MW
27 Oct, 09:00	89,820 MW	87,241 MW
27 Oct, 10:00	89,439 MW	86,317 MW
27 Oct, 11:00	89,545 MW	86,026 MW
27 Oct, 12:00	89,330 MW	86,241 MW
27 Oct, 13:00	89,386 MW	86,575 MW
27 Oct, 14:00	89,898 MW	87,283 MW
27 Oct, 15:00	90,553 MW	89,043 MW
27 Oct, 16:00	91,168 MW	91,138 MW
27 Oct, 17:00	92,441 MW	92,419 MW
27 Oct, 18:00	94,287 MW	93,407 MW
27 Oct, 19:00	94,717 MW	92,357 MW
27 Oct, 20:00	92,938 MW	89,296 MW
27 Oct, 21:00	89,835 MW	85,079 MW
27 Oct, 22:00	85,286 MW	80,886 MW
27 Oct, 23:00	81,771 MW	77,824 MW
28 Oct, 00:00	79,858 MW	75,736 MW
28 Oct, 01:00	78,949 MW	74,614 MW
28 Oct, 02:00	77,863 MW	74,294 MW
28 Oct, 03:00	77,713 MW	75,538 MW
28 Oct, 04:00	78,527 MW	79,168 MW
28 Oct, 05:00	80,593 MW	85,394 MW
28 Oct, 06:00	86,630 MW	89,535 MW
28 Oct, 07:00	91,035 MW	89,789 MW

Assumptions

Only hours with both a forecast and a positive demand reading count (719 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). PJM Demand Forecast Accuracy: Error, Bias and Worst Miss. https://worldpowermonitor.com/forecast-accuracy/pjm/

Plain text

World Power Monitor. PJM 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/pjm/

BibTeX

@misc{wpm_forecast_accuracy_pjm_2026,
  title = {{PJM 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/pjm/}
}

Permalink: https://worldpowermonitor.com/forecast-accuracy/pjm/

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

Key Facts

Forecast Error at a Glance

Forecast and Reported Demand, Last 7 Days

Assumptions

Related