Belgium Demand Forecast Accuracy: Error, Bias and Worst Miss, 23 August to 20 September 2026
The day-ahead demand forecast for Belgium was off by 3.1% on average (mean absolute percentage error) over 687 hours from 23 August to 20 September 2026, and 82% of hours landed within 5% of the reading. Its bias was -0.2%: it ran close to balanced on average. The largest miss was 1,262 MW (12.2%) too high at 28 Aug 2026, 13:00 CEST (UTC+02:00). Dates and times are local (Europe/Brussels).
Key Facts
- The day-ahead demand forecast for Belgium was off by 3.1% on average (mean absolute percentage error) over 687 hours from 23 August to 20 September 2026, and 82% of hours landed within 5% of the reading. Its bias was -0.2%: it ran close to balanced on average. The largest miss was 1,262 MW (12.2%) too high at 28 Aug 2026, 13:00 CEST (UTC+02:00).
- Across 47 European bidding zones ranked by average error over their own latest 30 day windows, Belgium came 18 (1 is the smallest error).
- On average the forecast differed from reported demand by 276 MW, against average demand of 8,978 MW.
- The forecast was above reported demand in 48% of compared hours.
Forecast Error at a Glance
687 hours from 23 August to 20 September 2026Average error3.1%
Bias-0.2%
Hours within 5%82%
Worst miss1,262 MW
Average error is the mean absolute percentage gap between the forecast and reported demand. Bias is the signed mean (-19 MW per hour on average): the forecast ran close to balanced on average. The worst miss was 1,262 MW (12.2%) too high at 28 Aug 2026, 13:00 CEST (UTC+02:00): forecast 11,590 MW, reported 10,328 MW.
Source: ENTSO-E Transparency Platform (transparency.entsoe.eu), CC BY 4.0. Aggregated and converted by World Power Monitor; ENTSO-E does not endorse this site. (ENTSO-E Terms of Use plus CC BY 4.0 for listed data items) 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, 14:00 CEST (UTC+02:00)Data to 2026-09-20
| Local hour | Reported demand | Day-ahead forecast |
|---|---|---|
| 13 Sept, 15:00 | 8,635 MW | 9,047 MW |
| 13 Sept, 16:00 | 8,352 MW | 8,520 MW |
| 13 Sept, 17:00 | 8,505 MW | 8,103 MW |
| 13 Sept, 18:00 | 9,006 MW | 8,227 MW |
| 13 Sept, 19:00 | 8,787 MW | 8,366 MW |
| 13 Sept, 20:00 | 8,787 MW | 8,548 MW |
| 13 Sept, 21:00 | 8,591 MW | 8,416 MW |
| 13 Sept, 22:00 | 8,319 MW | 8,124 MW |
| 13 Sept, 23:00 | 7,858 MW | 7,725 MW |
| 14 Sept, 00:00 | 7,382 MW | 7,459 MW |
| 14 Sept, 01:00 | 7,154 MW | 7,255 MW |
| 14 Sept, 02:00 | 7,063 MW | 7,216 MW |
| 14 Sept, 03:00 | 7,056 MW | 7,136 MW |
| 14 Sept, 04:00 | 7,141 MW | 7,191 MW |
| 14 Sept, 05:00 | 7,470 MW | 7,490 MW |
| 14 Sept, 06:00 | 8,279 MW | 8,302 MW |
| 14 Sept, 07:00 | 9,142 MW | 9,085 MW |
| 14 Sept, 08:00 | 9,953 MW | 9,872 MW |
| 14 Sept, 09:00 | 10,523 MW | 10,308 MW |
| 14 Sept, 10:00 | 10,560 MW | 10,473 MW |
| 14 Sept, 11:00 | 10,642 MW | 11,048 MW |
| 14 Sept, 12:00 | 10,462 MW | 11,263 MW |
| 14 Sept, 13:00 | 10,484 MW | 11,281 MW |
| 14 Sept, 14:00 | 10,578 MW | 10,920 MW |
| 14 Sept, 15:00 | 10,512 MW | 10,148 MW |
| 14 Sept, 16:00 | 10,329 MW | 9,835 MW |
| 14 Sept, 17:00 | 10,209 MW | 9,959 MW |
| 14 Sept, 18:00 | 10,046 MW | 9,937 MW |
| 14 Sept, 19:00 | 9,712 MW | 9,737 MW |
| 14 Sept, 20:00 | 9,495 MW | 9,523 MW |
| 14 Sept, 21:00 | 9,216 MW | 9,113 MW |
| 14 Sept, 22:00 | 8,997 MW | 8,722 MW |
| 14 Sept, 23:00 | 8,525 MW | 8,300 MW |
| 15 Sept, 00:00 | 8,133 MW | 7,888 MW |
| 15 Sept, 01:00 | 7,837 MW | 7,625 MW |
| 15 Sept, 02:00 | 7,624 MW | 7,565 MW |
| 15 Sept, 03:00 | 7,489 MW | 7,498 MW |
| 15 Sept, 04:00 | 7,494 MW | 7,445 MW |
| 15 Sept, 05:00 | 7,837 MW | 7,725 MW |
| 15 Sept, 06:00 | 8,609 MW | 8,435 MW |
| 15 Sept, 07:00 | 9,428 MW | 9,192 MW |
| 15 Sept, 08:00 | 10,328 MW | 10,050 MW |
| 15 Sept, 09:00 | 10,887 MW | 10,529 MW |
| 15 Sept, 10:00 | 11,083 MW | 10,640 MW |
| 15 Sept, 11:00 | 11,646 MW | 10,949 MW |
| 15 Sept, 12:00 | 11,699 MW | 10,945 MW |
| 15 Sept, 13:00 | 11,504 MW | 10,834 MW |
| 15 Sept, 14:00 | 11,048 MW | 10,312 MW |
| 15 Sept, 15:00 | 10,524 MW | 9,876 MW |
| 15 Sept, 16:00 | 10,323 MW | 9,603 MW |
| 15 Sept, 17:00 | 10,278 MW | 9,809 MW |
| 15 Sept, 18:00 | 10,160 MW | 10,288 MW |
| 15 Sept, 19:00 | 9,871 MW | 9,855 MW |
| 15 Sept, 20:00 | 9,690 MW | 9,765 MW |
| 15 Sept, 21:00 | 9,290 MW | 9,247 MW |
| 15 Sept, 22:00 | 9,068 MW | 8,830 MW |
| 15 Sept, 23:00 | 8,769 MW | 8,378 MW |
| 16 Sept, 00:00 | 8,370 MW | 7,985 MW |
| 16 Sept, 01:00 | 8,099 MW | 7,645 MW |
| 16 Sept, 02:00 | 7,857 MW | 7,366 MW |
| 16 Sept, 03:00 | 7,686 MW | 7,254 MW |
| 16 Sept, 04:00 | 7,758 MW | 7,342 MW |
| 16 Sept, 05:00 | 7,894 MW | 7,602 MW |
| 16 Sept, 06:00 | 8,548 MW | 8,403 MW |
| 16 Sept, 07:00 | 9,313 MW | 9,203 MW |
| 16 Sept, 08:00 | 10,076 MW | 9,818 MW |
| 16 Sept, 09:00 | 10,527 MW | 10,284 MW |
| 16 Sept, 10:00 | 10,652 MW | 10,474 MW |
| 16 Sept, 11:00 | 10,881 MW | 10,660 MW |
| 16 Sept, 12:00 | 11,075 MW | 10,496 MW |
| 16 Sept, 13:00 | 10,998 MW | 10,264 MW |
| 16 Sept, 14:00 | 10,579 MW | 10,164 MW |
| 16 Sept, 15:00 | 10,260 MW | 10,386 MW |
| 16 Sept, 16:00 | 9,871 MW | 10,086 MW |
| 16 Sept, 17:00 | 9,952 MW | 9,844 MW |
| 16 Sept, 18:00 | 9,967 MW | 9,817 MW |
| 16 Sept, 19:00 | 9,456 MW | 9,496 MW |
| 16 Sept, 20:00 | 9,589 MW | 9,364 MW |
| 16 Sept, 21:00 | 9,424 MW | 9,011 MW |
| 16 Sept, 22:00 | 9,120 MW | 8,564 MW |
| 16 Sept, 23:00 | 8,515 MW | 8,030 MW |
| 17 Sept, 00:00 | 7,998 MW | 7,658 MW |
| 17 Sept, 01:00 | 7,796 MW | 7,404 MW |
| 17 Sept, 02:00 | 7,613 MW | 7,215 MW |
| 17 Sept, 03:00 | 7,531 MW | 7,240 MW |
| 17 Sept, 04:00 | 7,659 MW | 7,227 MW |
| 17 Sept, 05:00 | 7,956 MW | 7,548 MW |
| 17 Sept, 06:00 | 8,636 MW | 8,460 MW |
| 17 Sept, 07:00 | 9,428 MW | 9,245 MW |
| 17 Sept, 08:00 | 10,030 MW | 9,977 MW |
| 17 Sept, 09:00 | 10,638 MW | 10,433 MW |
| 17 Sept, 10:00 | 10,808 MW | 10,830 MW |
| 17 Sept, 11:00 | 11,161 MW | 11,136 MW |
| 17 Sept, 12:00 | 10,710 MW | 10,946 MW |
| 17 Sept, 13:00 | 10,507 MW | 10,687 MW |
| 17 Sept, 14:00 | 10,048 MW | 10,288 MW |
| 17 Sept, 15:00 | 9,895 MW | 10,141 MW |
| 17 Sept, 16:00 | 9,833 MW | 9,944 MW |
| 17 Sept, 17:00 | 10,029 MW | 9,885 MW |
| 17 Sept, 18:00 | 10,100 MW | 9,831 MW |
| 17 Sept, 19:00 | 9,679 MW | 9,306 MW |
| 17 Sept, 20:00 | 9,478 MW | 9,300 MW |
| 17 Sept, 21:00 | 9,444 MW | 8,976 MW |
| 17 Sept, 22:00 | 9,191 MW | 8,560 MW |
| 17 Sept, 23:00 | 8,635 MW | 8,104 MW |
| 18 Sept, 00:00 | 8,387 MW | 7,881 MW |
| 18 Sept, 01:00 | 8,087 MW | 7,688 MW |
| 18 Sept, 02:00 | 7,916 MW | 7,556 MW |
| 18 Sept, 03:00 | 7,719 MW | 7,432 MW |
| 18 Sept, 04:00 | 7,601 MW | 7,484 MW |
| 18 Sept, 05:00 | 7,863 MW | 7,772 MW |
| 18 Sept, 06:00 | 8,612 MW | 8,538 MW |
| 18 Sept, 07:00 | 9,288 MW | 9,253 MW |
| 18 Sept, 08:00 | 9,957 MW | 9,869 MW |
| 18 Sept, 09:00 | 10,642 MW | 10,435 MW |
| 18 Sept, 10:00 | 10,869 MW | 10,535 MW |
| 18 Sept, 11:00 | 11,133 MW | 10,551 MW |
| 18 Sept, 12:00 | 10,953 MW | 10,370 MW |
| 18 Sept, 13:00 | 10,952 MW | 10,262 MW |
| 18 Sept, 14:00 | 10,623 MW | 9,911 MW |
| 18 Sept, 15:00 | 10,476 MW | 9,723 MW |
| 18 Sept, 16:00 | 10,095 MW | 9,991 MW |
| 18 Sept, 17:00 | 9,977 MW | 9,924 MW |
| 18 Sept, 18:00 | 9,826 MW | 9,781 MW |
| 18 Sept, 19:00 | 9,511 MW | 9,412 MW |
| 18 Sept, 20:00 | 9,354 MW | 9,175 MW |
| 18 Sept, 21:00 | 9,117 MW | 8,814 MW |
| 18 Sept, 22:00 | 8,973 MW | 8,540 MW |
| 18 Sept, 23:00 | 8,479 MW | 8,146 MW |
| 19 Sept, 00:00 | 8,058 MW | 7,678 MW |
| 19 Sept, 01:00 | 7,714 MW | 7,345 MW |
| 19 Sept, 02:00 | 7,458 MW | 7,072 MW |
| 19 Sept, 03:00 | 7,385 MW | 6,929 MW |
| 19 Sept, 04:00 | 7,256 MW | 6,874 MW |
| 19 Sept, 05:00 | 7,287 MW | 6,884 MW |
| 19 Sept, 06:00 | 7,561 MW | 7,125 MW |
| 19 Sept, 07:00 | 7,963 MW | 7,426 MW |
| 19 Sept, 08:00 | 8,407 MW | 8,006 MW |
| 19 Sept, 09:00 | 8,760 MW | 8,725 MW |
| 19 Sept, 10:00 | 9,073 MW | 9,320 MW |
| 19 Sept, 11:00 | 9,367 MW | 9,709 MW |
| 19 Sept, 12:00 | 9,177 MW | 9,860 MW |
| 19 Sept, 13:00 | 9,048 MW | 9,900 MW |
| 19 Sept, 14:00 | 8,931 MW | 9,536 MW |
| 19 Sept, 15:00 | 8,654 MW | 8,918 MW |
| 19 Sept, 16:00 | 8,544 MW | 8,635 MW |
| 19 Sept, 17:00 | 8,756 MW | 8,485 MW |
| 19 Sept, 18:00 | 8,879 MW | 8,467 MW |
| 19 Sept, 19:00 | 8,783 MW | 8,568 MW |
| 19 Sept, 20:00 | 8,826 MW | 8,568 MW |
| 19 Sept, 21:00 | 8,580 MW | 8,267 MW |
| 19 Sept, 22:00 | 8,397 MW | 8,018 MW |
| 19 Sept, 23:00 | 8,154 MW | 7,619 MW |
| 20 Sept, 00:00 | 7,724 MW | 7,382 MW |
| 20 Sept, 01:00 | 7,572 MW | 7,162 MW |
| 20 Sept, 02:00 | 7,391 MW | 7,008 MW |
| 20 Sept, 03:00 | 7,167 MW | 6,842 MW |
| 20 Sept, 04:00 | 7,026 MW | 6,811 MW |
| 20 Sept, 05:00 | 6,901 MW | 6,795 MW |
| 20 Sept, 06:00 | 7,266 MW | 7,057 MW |
| 20 Sept, 07:00 | 7,561 MW | 7,313 MW |
| 20 Sept, 08:00 | 7,852 MW | 7,577 MW |
| 20 Sept, 09:00 | 8,289 MW | 7,973 MW |
| 20 Sept, 10:00 | 8,652 MW | 8,530 MW |
| 20 Sept, 11:00 | 9,198 MW | 8,869 MW |
| 20 Sept, 12:00 | 9,602 MW | 8,879 MW |
| 20 Sept, 13:00 | 9,814 MW | 8,770 MW |
| 20 Sept, 14:00 | 9,150 MW | 8,791 MW |
Assumptions
- Only hours with both a forecast and a positive demand reading count (687 of 687 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.
- European figures are for the ENTSO-E bidding zone named on this page. US and European grids are ranked separately.