MISO Demand Forecast Accuracy: Error, Bias and Worst Miss, 21 August to 20 September 2026
The day-ahead demand forecast for MISO was off by 2.1% on average (mean absolute percentage error) over 719 hours from 21 August to 20 September 2026, and 96% of hours landed within 5% of the reading. Its bias was +1.8%: it ran high on average, an over forecast. The largest miss was 7,452 MW (6.9%) too high at 4 Sept 2026, 14:00 EDT (UTC-04:00). Dates and times are local (America/New_York).
Key Facts
- The day-ahead demand forecast for MISO was off by 2.1% on average (mean absolute percentage error) over 719 hours from 21 August to 20 September 2026, and 96% of hours landed within 5% of the reading. Its bias was +1.8%: it ran high on average, an over forecast. The largest miss was 7,452 MW (6.9%) too high at 4 Sept 2026, 14:00 EDT (UTC-04:00).
- Across 53 US grids ranked by average error over their own latest 30 day windows, MISO came 8 (1 is the smallest error).
- On average the forecast differed from reported demand by 1,859 MW, against average demand of 86,448 MW.
- The forecast was above reported demand in 84% of compared hours.
Forecast Error at a Glance
719 hours from 21 August to 20 September 2026Average error2.1%
Bias+1.8%
Hours within 5%96%
Worst miss7,452 MW
Average error is the mean absolute percentage gap between the forecast and reported demand. Bias is the signed mean (+1,620 MW per hour on average): the forecast ran high on average, an over forecast. The worst miss was 7,452 MW (6.9%) too high at 4 Sept 2026, 14:00 EDT (UTC-04:00): forecast 115.3 GW, reported 107.9 GW.
Source: U.S. Energy Information Administration (EIA). (US Government work, public domain) Data as of 2026-09-20. 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 20 Sept 2026, 21:00 EDT (UTC-04:00)Data to 2026-09-20
| Local hour | Reported demand | Day-ahead forecast |
|---|---|---|
| 13 Sept, 22:00 | 79,634 MW | 81,907 MW |
| 13 Sept, 23:00 | 75,030 MW | 77,172 MW |
| 14 Sept, 00:00 | 71,805 MW | 74,198 MW |
| 14 Sept, 01:00 | 69,165 MW | 71,729 MW |
| 14 Sept, 02:00 | 67,915 MW | 69,664 MW |
| 14 Sept, 03:00 | 66,740 MW | 68,396 MW |
| 14 Sept, 04:00 | 65,856 MW | 68,060 MW |
| 14 Sept, 05:00 | 66,444 MW | 68,595 MW |
| 14 Sept, 06:00 | 69,310 MW | 71,902 MW |
| 14 Sept, 07:00 | 72,857 MW | 74,820 MW |
| 14 Sept, 08:00 | 74,207 MW | 76,913 MW |
| 14 Sept, 09:00 | 75,980 MW | 78,841 MW |
| 14 Sept, 10:00 | 78,647 MW | 81,329 MW |
| 14 Sept, 11:00 | 81,153 MW | 84,260 MW |
| 14 Sept, 12:00 | 84,327 MW | 87,161 MW |
| 14 Sept, 13:00 | 87,105 MW | 89,775 MW |
| 14 Sept, 14:00 | 89,437 MW | 91,959 MW |
| 14 Sept, 15:00 | 90,553 MW | 93,294 MW |
| 14 Sept, 16:00 | 91,735 MW | 94,350 MW |
| 14 Sept, 17:00 | 92,067 MW | 95,146 MW |
| 14 Sept, 18:00 | 91,703 MW | 95,149 MW |
| 14 Sept, 19:00 | 90,151 MW | 93,923 MW |
| 14 Sept, 20:00 | 88,981 MW | 92,301 MW |
| 14 Sept, 21:00 | 86,577 MW | 89,880 MW |
| 14 Sept, 22:00 | 82,756 MW | 85,904 MW |
| 14 Sept, 23:00 | 78,235 MW | 81,138 MW |
| 15 Sept, 00:00 | 74,451 MW | 77,097 MW |
| 15 Sept, 01:00 | 72,207 MW | 74,617 MW |
| 15 Sept, 02:00 | 70,758 MW | 72,392 MW |
| 15 Sept, 03:00 | 69,306 MW | 70,952 MW |
| 15 Sept, 04:00 | 68,997 MW | 70,430 MW |
| 15 Sept, 05:00 | 69,244 MW | 71,446 MW |
| 15 Sept, 06:00 | 71,826 MW | 73,674 MW |
| 15 Sept, 07:00 | 75,376 MW | 76,495 MW |
| 15 Sept, 08:00 | 77,350 MW | 78,854 MW |
| 15 Sept, 09:00 | 79,140 MW | 80,931 MW |
| 15 Sept, 10:00 | 82,016 MW | 83,975 MW |
| 15 Sept, 11:00 | 85,659 MW | 87,888 MW |
| 15 Sept, 12:00 | 89,591 MW | 91,890 MW |
| 15 Sept, 13:00 | 93,217 MW | 95,414 MW |
| 15 Sept, 14:00 | 96,498 MW | 98,361 MW |
| 15 Sept, 15:00 | 98,565 MW | 100.3 GW |
| 15 Sept, 16:00 | 100.2 GW | 101.4 GW |
| 15 Sept, 17:00 | 100.5 GW | 102.0 GW |
| 15 Sept, 18:00 | 100.3 GW | 101.6 GW |
| 15 Sept, 19:00 | 98,387 MW | 100.2 GW |
| 15 Sept, 20:00 | 97,356 MW | 98,116 MW |
| 15 Sept, 21:00 | 94,529 MW | 95,125 MW |
| 15 Sept, 22:00 | 90,004 MW | 90,428 MW |
| 15 Sept, 23:00 | 84,726 MW | 84,885 MW |
| 16 Sept, 00:00 | 81,081 MW | 80,879 MW |
| 16 Sept, 01:00 | 77,869 MW | 77,607 MW |
| 16 Sept, 02:00 | 75,491 MW | 74,857 MW |
| 16 Sept, 03:00 | 73,729 MW | 73,071 MW |
| 16 Sept, 04:00 | 72,738 MW | 72,332 MW |
| 16 Sept, 05:00 | 73,342 MW | 73,245 MW |
| 16 Sept, 06:00 | 75,639 MW | 75,375 MW |
| 16 Sept, 07:00 | 79,005 MW | 78,028 MW |
| 16 Sept, 08:00 | 80,647 MW | 80,162 MW |
| 16 Sept, 09:00 | 82,252 MW | 82,287 MW |
| 16 Sept, 10:00 | 84,606 MW | 85,259 MW |
| 16 Sept, 11:00 | 87,169 MW | 88,812 MW |
| 16 Sept, 12:00 | 90,375 MW | 92,239 MW |
| 16 Sept, 13:00 | 93,757 MW | 95,320 MW |
| 16 Sept, 14:00 | 96,431 MW | 97,808 MW |
| 16 Sept, 15:00 | 97,913 MW | 99,120 MW |
| 16 Sept, 16:00 | 99,044 MW | 99,964 MW |
| 16 Sept, 17:00 | 98,975 MW | 100.4 GW |
| 16 Sept, 18:00 | 98,100 MW | 100.1 GW |
| 16 Sept, 19:00 | 96,232 MW | 98,579 MW |
| 16 Sept, 20:00 | 94,651 MW | 96,523 MW |
| 16 Sept, 21:00 | 92,487 MW | 93,924 MW |
| 16 Sept, 22:00 | 88,209 MW | 89,727 MW |
| 16 Sept, 23:00 | 83,729 MW | 84,677 MW |
| 17 Sept, 00:00 | 80,015 MW | 80,214 MW |
| 17 Sept, 01:00 | 77,328 MW | 78,439 MW |
| 17 Sept, 02:00 | 74,632 MW | 75,723 MW |
| 17 Sept, 03:00 | 73,021 MW | 73,970 MW |
| 17 Sept, 04:00 | 72,344 MW | 73,295 MW |
| 17 Sept, 05:00 | 73,073 MW | 73,803 MW |
| 17 Sept, 06:00 | 75,847 MW | 76,378 MW |
| 17 Sept, 07:00 | 79,045 MW | 79,108 MW |
| 17 Sept, 08:00 | 80,942 MW | 82,392 MW |
| 17 Sept, 09:00 | 82,358 MW | 84,876 MW |
| 17 Sept, 10:00 | 85,535 MW | 88,088 MW |
| 17 Sept, 11:00 | 88,724 MW | 91,823 MW |
| 17 Sept, 12:00 | 91,715 MW | 94,686 MW |
| 17 Sept, 13:00 | 94,873 MW | 97,828 MW |
| 17 Sept, 14:00 | 97,246 MW | 100.3 GW |
| 17 Sept, 15:00 | 98,699 MW | 101.9 GW |
| 17 Sept, 16:00 | 99,636 MW | 102.9 GW |
| 17 Sept, 17:00 | 100.1 GW | 103.2 GW |
| 17 Sept, 18:00 | 99,331 MW | 102.6 GW |
| 17 Sept, 19:00 | 97,441 MW | 100.8 GW |
| 17 Sept, 20:00 | 95,306 MW | 98,953 MW |
| 17 Sept, 21:00 | 92,678 MW | 96,014 MW |
| 17 Sept, 22:00 | 88,291 MW | 91,328 MW |
| 17 Sept, 23:00 | 83,631 MW | 85,760 MW |
| 18 Sept, 00:00 | 80,045 MW | 80,574 MW |
| 18 Sept, 01:00 | 77,004 MW | 77,334 MW |
| 18 Sept, 02:00 | 74,610 MW | 75,409 MW |
| 18 Sept, 03:00 | 73,100 MW | 73,499 MW |
| 18 Sept, 04:00 | 71,739 MW | 72,596 MW |
| 18 Sept, 05:00 | 71,939 MW | 72,428 MW |
| 18 Sept, 06:00 | 74,209 MW | 75,069 MW |
| 18 Sept, 07:00 | 77,098 MW | 77,460 MW |
| 18 Sept, 08:00 | 78,632 MW | 80,403 MW |
| 18 Sept, 09:00 | 80,663 MW | 82,731 MW |
| 18 Sept, 10:00 | 83,678 MW | 85,874 MW |
| 18 Sept, 11:00 | 86,667 MW | 89,421 MW |
| 18 Sept, 12:00 | 89,678 MW | 91,981 MW |
| 18 Sept, 13:00 | 92,618 MW | 94,882 MW |
| 18 Sept, 14:00 | 94,909 MW | 97,167 MW |
| 18 Sept, 15:00 | 96,280 MW | 98,358 MW |
| 18 Sept, 16:00 | 96,880 MW | 98,942 MW |
| 18 Sept, 17:00 | 96,568 MW | 98,934 MW |
| 18 Sept, 18:00 | 95,479 MW | 97,808 MW |
| 18 Sept, 19:00 | 93,107 MW | 95,286 MW |
| 18 Sept, 20:00 | 90,786 MW | 92,522 MW |
| 18 Sept, 21:00 | 87,690 MW | 89,689 MW |
| 18 Sept, 22:00 | 83,775 MW | 85,954 MW |
| 18 Sept, 23:00 | 79,716 MW | 81,362 MW |
| 19 Sept, 00:00 | 75,745 MW | 76,866 MW |
| 19 Sept, 01:00 | 73,218 MW | 72,840 MW |
| 19 Sept, 02:00 | 71,190 MW | 70,990 MW |
| 19 Sept, 03:00 | 69,564 MW | 70,097 MW |
| 19 Sept, 04:00 | 68,308 MW | 68,943 MW |
| 19 Sept, 05:00 | 68,037 MW | 68,285 MW |
| 19 Sept, 06:00 | 68,689 MW | 68,374 MW |
| 19 Sept, 07:00 | 69,876 MW | 68,704 MW |
| 19 Sept, 08:00 | 70,357 MW | 71,452 MW |
| 19 Sept, 09:00 | 73,431 MW | 75,671 MW |
| 19 Sept, 10:00 | 77,384 MW | 78,529 MW |
| 19 Sept, 11:00 | 80,852 MW | 82,420 MW |
| 19 Sept, 12:00 | 84,128 MW | 85,295 MW |
| 19 Sept, 13:00 | 86,768 MW | 88,483 MW |
| 19 Sept, 14:00 | 88,812 MW | 91,092 MW |
| 19 Sept, 15:00 | 90,241 MW | 92,862 MW |
| 19 Sept, 16:00 | 91,471 MW | 94,135 MW |
| 19 Sept, 17:00 | 91,891 MW | 94,545 MW |
| 19 Sept, 18:00 | 91,792 MW | 93,947 MW |
| 19 Sept, 19:00 | 90,302 MW | 92,143 MW |
| 19 Sept, 20:00 | 88,050 MW | 90,073 MW |
| 19 Sept, 21:00 | 85,233 MW | 87,622 MW |
| 19 Sept, 22:00 | 81,548 MW | 83,953 MW |
| 19 Sept, 23:00 | 77,842 MW | 79,564 MW |
| 20 Sept, 00:00 | 74,478 MW | 75,342 MW |
| 20 Sept, 01:00 | 73,895 MW | 72,012 MW |
| 20 Sept, 02:00 | 71,680 MW | 70,226 MW |
| 20 Sept, 03:00 | 69,931 MW | 68,357 MW |
| 20 Sept, 04:00 | 68,613 MW | 68,045 MW |
| 20 Sept, 05:00 | 68,177 MW | 67,543 MW |
| 20 Sept, 06:00 | 68,390 MW | 67,731 MW |
| 20 Sept, 07:00 | 69,419 MW | 67,505 MW |
| 20 Sept, 08:00 | 70,616 MW | 69,101 MW |
| 20 Sept, 09:00 | 73,818 MW | 73,179 MW |
| 20 Sept, 10:00 | 77,345 MW | 76,021 MW |
| 20 Sept, 11:00 | 80,980 MW | 79,839 MW |
| 20 Sept, 12:00 | 84,662 MW | 83,029 MW |
| 20 Sept, 13:00 | 87,687 MW | 85,689 MW |
| 20 Sept, 14:00 | 90,018 MW | 88,058 MW |
| 20 Sept, 15:00 | 91,593 MW | 89,674 MW |
| 20 Sept, 16:00 | 92,755 MW | 91,023 MW |
| 20 Sept, 17:00 | 93,745 MW | 91,785 MW |
| 20 Sept, 18:00 | 94,043 MW | 91,685 MW |
| 20 Sept, 19:00 | 92,648 MW | 90,355 MW |
| 20 Sept, 20:00 | 91,503 MW | 88,747 MW |
| 20 Sept, 21:00 | 88,549 MW | 86,291 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.