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

ISO-NE Demand Forecast Accuracy: Error, Bias and Worst Miss, 28 September to 28 October 2026

The day-ahead demand forecast for ISO-NE was off by 3.3% on average (mean absolute percentage error) over 719 hours from 28 September to 28 October 2026, and 74% of hours landed within 5% of the reading. Its bias was -2.8%: it ran low on average, an under forecast. The largest miss was 1,662 MW (17.6%) too low at 23 Oct 2026, 11:00 EDT (UTC-04:00). Dates and times are local (America/New_York).

Key Facts

  • The day-ahead demand forecast for ISO-NE was off by 3.3% on average (mean absolute percentage error) over 719 hours from 28 September to 28 October 2026, and 74% of hours landed within 5% of the reading. Its bias was -2.8%: it ran low on average, an under forecast. The largest miss was 1,662 MW (17.6%) too low at 23 Oct 2026, 11:00 EDT (UTC-04:00).
  • Across 53 US grids ranked by average error over their own latest 30 day windows, ISO-NE came 22 (1 is the smallest error).
  • On average the forecast differed from reported demand by 347 MW, against average demand of 11,480 MW.
  • The forecast was above reported demand in 24% of compared hours.

Forecast Error at a Glance

719 hours from 28 September to 28 October 2026
Average error3.3%
Bias-2.8%
Hours within 5%74%
Worst miss1,662 MW

Average error is the mean absolute percentage gap between the forecast and reported demand. Bias is the signed mean (-282 MW per hour on average): the forecast ran low on average, an under forecast. The worst miss was 1,662 MW (17.6%) too low at 23 Oct 2026, 11:00 EDT (UTC-04:00): forecast 7,760 MW, reported 9,422 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)
ISO-NE day-ahead demand forecast and reported demand by hour Hourly reported demand and the day-ahead forecast for ISO-NE 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. 0 3,750 7,500 11,250 15,000 21 Oct, 08:0022 Oct, 08:0023 Oct, 08:0024 Oct, 08:0025 Oct, 08:0026 Oct, 08:0027 Oct, 08:00
Hourly reported demand and the day-ahead forecast for ISO-NE 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 hourReported demandDay-ahead forecast
21 Oct, 08:0012,431 MW12,410 MW
21 Oct, 09:0010,981 MW10,920 MW
21 Oct, 10:0010,020 MW9,630 MW
21 Oct, 11:009,541 MW8,940 MW
21 Oct, 12:009,691 MW8,860 MW
21 Oct, 13:009,724 MW9,020 MW
21 Oct, 14:0010,039 MW9,580 MW
21 Oct, 15:0010,632 MW10,450 MW
21 Oct, 16:0012,061 MW12,030 MW
21 Oct, 17:0013,517 MW13,700 MW
21 Oct, 18:0014,282 MW14,350 MW
21 Oct, 19:0014,120 MW14,110 MW
21 Oct, 20:0013,589 MW13,590 MW
21 Oct, 21:0012,846 MW12,800 MW
21 Oct, 22:0011,826 MW11,810 MW
21 Oct, 23:0010,932 MW10,920 MW
22 Oct, 00:0010,804 MW10,380 MW
22 Oct, 01:0010,820 MW9,990 MW
22 Oct, 02:0010,650 MW9,790 MW
22 Oct, 03:0010,624 MW9,790 MW
22 Oct, 04:0010,907 MW10,070 MW
22 Oct, 05:0010,971 MW10,930 MW
22 Oct, 06:0012,380 MW12,440 MW
22 Oct, 07:0013,281 MW13,210 MW
22 Oct, 08:0012,882 MW12,470 MW
22 Oct, 09:0011,595 MW11,530 MW
22 Oct, 10:0010,718 MW9,850 MW
22 Oct, 11:0010,009 MW9,010 MW
22 Oct, 12:009,567 MW8,650 MW
22 Oct, 13:009,688 MW8,820 MW
22 Oct, 14:0010,115 MW9,230 MW
22 Oct, 15:0010,739 MW10,230 MW
22 Oct, 16:0011,984 MW11,800 MW
22 Oct, 17:0013,422 MW13,350 MW
22 Oct, 18:0014,104 MW14,000 MW
22 Oct, 19:0013,950 MW13,800 MW
22 Oct, 20:0013,473 MW13,330 MW
22 Oct, 21:0012,767 MW12,610 MW
22 Oct, 22:0011,817 MW11,680 MW
22 Oct, 23:0011,165 MW10,850 MW
23 Oct, 00:0010,848 MW10,310 MW
23 Oct, 01:0010,740 MW9,930 MW
23 Oct, 02:0010,636 MW9,750 MW
23 Oct, 03:0010,577 MW9,730 MW
23 Oct, 04:0010,622 MW10,100 MW
23 Oct, 05:0011,207 MW11,010 MW
23 Oct, 06:0012,272 MW12,550 MW
23 Oct, 07:0013,088 MW13,420 MW
23 Oct, 08:0012,190 MW12,350 MW
23 Oct, 09:0010,419 MW10,150 MW
23 Oct, 10:009,734 MW8,640 MW
23 Oct, 11:009,422 MW7,760 MW
23 Oct, 12:009,077 MW7,750 MW
23 Oct, 13:009,131 MW8,040 MW
23 Oct, 14:009,596 MW8,600 MW
23 Oct, 15:0010,134 MW9,780 MW
23 Oct, 16:0011,517 MW11,500 MW
23 Oct, 17:0013,171 MW13,170 MW
23 Oct, 18:0013,729 MW13,900 MW
23 Oct, 19:0013,581 MW13,620 MW
23 Oct, 20:0013,281 MW13,250 MW
23 Oct, 21:0012,784 MW12,680 MW
23 Oct, 22:0012,097 MW11,930 MW
23 Oct, 23:0011,351 MW11,150 MW
24 Oct, 00:0010,801 MW10,670 MW
24 Oct, 01:0010,442 MW10,380 MW
24 Oct, 02:0010,279 MW10,170 MW
24 Oct, 03:0010,229 MW10,150 MW
24 Oct, 04:0010,365 MW10,290 MW
24 Oct, 05:0010,760 MW10,640 MW
24 Oct, 06:0011,513 MW11,390 MW
24 Oct, 07:0012,159 MW11,980 MW
24 Oct, 08:0011,597 MW11,060 MW
24 Oct, 09:0010,368 MW10,320 MW
24 Oct, 10:009,355 MW8,820 MW
24 Oct, 11:008,585 MW7,570 MW
24 Oct, 12:008,472 MW6,990 MW
24 Oct, 13:008,632 MW7,080 MW
24 Oct, 14:008,894 MW7,610 MW
24 Oct, 15:009,707 MW8,620 MW
24 Oct, 16:0010,927 MW10,460 MW
24 Oct, 17:0012,537 MW12,240 MW
24 Oct, 18:0013,160 MW13,200 MW
24 Oct, 19:0013,011 MW12,870 MW
24 Oct, 20:0012,724 MW12,610 MW
24 Oct, 21:0012,278 MW12,130 MW
24 Oct, 22:0011,673 MW11,480 MW
24 Oct, 23:0011,051 MW10,820 MW
25 Oct, 00:0010,647 MW10,610 MW
25 Oct, 01:0010,734 MW10,280 MW
25 Oct, 02:0010,649 MW10,080 MW
25 Oct, 03:0010,606 MW10,120 MW
25 Oct, 04:0010,175 MW10,110 MW
25 Oct, 05:0010,433 MW10,400 MW
25 Oct, 06:0011,022 MW11,070 MW
25 Oct, 07:0011,589 MW11,410 MW
25 Oct, 08:0011,022 MW10,720 MW
25 Oct, 09:0010,103 MW8,910 MW
25 Oct, 10:009,342 MW7,930 MW
25 Oct, 11:008,621 MW7,250 MW
25 Oct, 12:008,341 MW6,880 MW
25 Oct, 13:008,413 MW7,120 MW
25 Oct, 14:009,042 MW7,960 MW
25 Oct, 15:0010,252 MW9,070 MW
25 Oct, 16:0011,432 MW11,680 MW
25 Oct, 17:0013,031 MW13,200 MW
25 Oct, 18:0013,688 MW14,000 MW
25 Oct, 19:0013,459 MW13,640 MW
25 Oct, 20:0012,982 MW12,930 MW
25 Oct, 21:0012,235 MW12,190 MW
25 Oct, 22:0011,479 MW11,370 MW
25 Oct, 23:0010,958 MW10,610 MW
26 Oct, 00:0010,753 MW10,050 MW
26 Oct, 01:0010,449 MW9,750 MW
26 Oct, 02:0010,545 MW9,610 MW
26 Oct, 03:0010,659 MW9,650 MW
26 Oct, 04:0010,915 MW10,000 MW
26 Oct, 05:0011,225 MW10,900 MW
26 Oct, 06:0012,630 MW12,370 MW
26 Oct, 07:0013,556 MW13,240 MW
26 Oct, 08:0012,791 MW12,470 MW
26 Oct, 09:0011,638 MW11,030 MW
26 Oct, 10:0010,881 MW10,050 MW
26 Oct, 11:0010,443 MW9,400 MW
26 Oct, 12:0010,540 MW9,200 MW
26 Oct, 13:0010,483 MW9,600 MW
26 Oct, 14:0010,993 MW9,940 MW
26 Oct, 15:0011,297 MW10,720 MW
26 Oct, 16:0012,553 MW12,320 MW
26 Oct, 17:0013,835 MW13,880 MW
26 Oct, 18:0014,372 MW14,100 MW
26 Oct, 19:0014,040 MW13,810 MW
26 Oct, 20:0013,450 MW13,410 MW
26 Oct, 21:0012,681 MW12,620 MW
26 Oct, 22:0011,895 MW11,590 MW
26 Oct, 23:0011,035 MW10,670 MW
27 Oct, 00:0011,039 MW10,090 MW
27 Oct, 01:0010,967 MW9,710 MW
27 Oct, 02:0010,768 MW9,510 MW
27 Oct, 03:0010,674 MW9,500 MW
27 Oct, 04:0010,928 MW9,800 MW
27 Oct, 05:0011,264 MW10,720 MW
27 Oct, 06:0012,135 MW12,260 MW
27 Oct, 07:0012,974 MW13,050 MW
27 Oct, 08:0012,239 MW12,170 MW
27 Oct, 09:0011,005 MW10,620 MW
27 Oct, 10:0010,137 MW9,250 MW
27 Oct, 11:009,416 MW8,380 MW
27 Oct, 12:009,017 MW8,120 MW
27 Oct, 13:009,147 MW8,240 MW
27 Oct, 14:009,637 MW9,040 MW
27 Oct, 15:009,999 MW10,180 MW
27 Oct, 16:0011,876 MW11,970 MW
27 Oct, 17:0013,685 MW13,640 MW
27 Oct, 18:0014,393 MW14,400 MW
27 Oct, 19:0014,232 MW14,240 MW
27 Oct, 20:0013,762 MW13,790 MW
27 Oct, 21:0013,112 MW13,060 MW
27 Oct, 22:0012,193 MW12,090 MW
27 Oct, 23:0011,462 MW11,240 MW
28 Oct, 00:0011,413 MW10,750 MW
28 Oct, 01:0011,056 MW10,410 MW
28 Oct, 02:0011,112 MW10,280 MW
28 Oct, 03:0011,083 MW10,310 MW
28 Oct, 04:0011,126 MW10,660 MW
28 Oct, 05:0011,799 MW11,540 MW
28 Oct, 06:0013,182 MW13,120 MW
28 Oct, 07:0014,060 MW13,950 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). ISO-NE Demand Forecast Accuracy: Error, Bias and Worst Miss. https://worldpowermonitor.com/forecast-accuracy/iso-ne/

Plain text

World Power Monitor. ISO-NE 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/iso-ne/

BibTeX 
@misc{wpm_forecast_accuracy_iso_ne_2026,
  title = {{ISO-NE 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/iso-ne/}
}

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