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Built 2026-10-28 (28 October 2026)

Greece Demand Forecast Accuracy: Error, Bias and Worst Miss, 30 September to 28 October 2026

The day-ahead demand forecast for Greece was off by 3.4% on average (mean absolute percentage error) over 661 hours from 30 September to 28 October 2026, and 77% 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 1,656 MW (21.5%) too low at 2 Oct 2026, 12:00 EEST (UTC+03:00). Dates and times are local (Europe/Athens).

Key Facts

  • The day-ahead demand forecast for Greece was off by 3.4% on average (mean absolute percentage error) over 661 hours from 30 September to 28 October 2026, and 77% 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 1,656 MW (21.5%) too low at 2 Oct 2026, 12:00 EEST (UTC+03:00).
  • Across 47 European bidding zones ranked by average error over their own latest 30 day windows, Greece came 27 (1 is the smallest error).
  • On average the forecast differed from reported demand by 202 MW, against average demand of 5,222 MW.
  • The forecast was above reported demand in 49% of compared hours.

Forecast Error at a Glance

661 hours from 30 September to 28 October 2026
Average error3.4%
Bias-1.1%
Hours within 5%77%
Worst miss1,656 MW

Average error is the mean absolute percentage gap between the forecast and reported demand. Bias is the signed mean (-86 MW per hour on average): the forecast ran low on average, an under forecast. The worst miss was 1,656 MW (21.5%) too low at 2 Oct 2026, 12:00 EEST (UTC+03:00): forecast 6,053 MW, reported 7,708 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 2026-10-28. 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, 13:00 EET (UTC+02:00)
Greece day-ahead demand forecast and reported demand by hour Hourly reported demand and the day-ahead forecast for Greece over the last 7 days of the window, to 28 Oct 2026, 13:00 EET (UTC+02:00). Gaps are hours with a missing, zero or implausible report. 0 2,000 4,000 6,000 8,000 21 Oct, 15:0022 Oct, 15:0023 Oct, 15:0024 Oct, 15:0025 Oct, 14:0026 Oct, 14:0027 Oct, 14:00
Hourly reported demand and the day-ahead forecast for Greece over the last 7 days of the window, to 28 Oct 2026, 13:00 EET (UTC+02:00). 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, 15:005,800 MW5,610 MW
21 Oct, 16:005,730 MW5,450 MW
21 Oct, 17:005,699 MW5,458 MW
21 Oct, 18:005,729 MW5,685 MW
21 Oct, 19:006,103 MW6,150 MW
21 Oct, 20:006,102 MW6,155 MW
21 Oct, 21:005,759 MW5,783 MW
21 Oct, 22:005,252 MW5,330 MW
21 Oct, 23:004,844 MW4,940 MW
22 Oct, 00:004,507 MW4,555 MW
22 Oct, 01:004,214 MW4,288 MW
22 Oct, 02:004,109 MW4,165 MW
22 Oct, 03:004,072 MW4,100 MW
22 Oct, 04:004,054 MW4,090 MW
22 Oct, 05:004,194 MW4,220 MW
22 Oct, 06:004,564 MW4,608 MW
22 Oct, 07:005,150 MW5,153 MW
22 Oct, 08:005,548 MW5,510 MW
22 Oct, 09:006,048 MW5,838 MW
22 Oct, 10:006,379 MW5,990 MW
22 Oct, 11:006,476 MW6,100 MW
22 Oct, 12:006,525 MW6,160 MW
22 Oct, 13:006,355 MW6,135 MW
22 Oct, 14:006,305 MW5,903 MW
22 Oct, 15:006,141 MW5,618 MW
22 Oct, 16:005,757 MW5,450 MW
22 Oct, 17:005,573 MW5,470 MW
22 Oct, 18:005,756 MW5,685 MW
22 Oct, 19:006,101 MW6,100 MW
22 Oct, 20:006,083 MW6,080 MW
22 Oct, 21:005,736 MW5,710 MW
22 Oct, 22:005,262 MW5,270 MW
22 Oct, 23:004,809 MW4,908 MW
23 Oct, 00:004,501 MW4,540 MW
23 Oct, 01:004,269 MW4,300 MW
23 Oct, 02:004,140 MW4,170 MW
23 Oct, 03:004,057 MW4,110 MW
23 Oct, 04:004,107 MW4,098 MW
23 Oct, 05:004,231 MW4,218 MW
23 Oct, 06:004,594 MW4,608 MW
23 Oct, 07:005,099 MW5,115 MW
23 Oct, 08:005,334 MW5,475 MW
23 Oct, 09:005,553 MW5,793 MW
23 Oct, 10:005,599 MW5,950 MW
23 Oct, 11:005,684 MW6,010 MW
23 Oct, 12:005,680 MW6,073 MW
23 Oct, 13:005,756 MW6,070 MW
23 Oct, 14:005,642 MW5,848 MW
23 Oct, 15:005,448 MW5,608 MW
23 Oct, 16:005,231 MW5,443 MW
23 Oct, 17:005,271 MW5,465 MW
23 Oct, 18:005,586 MW5,648 MW
23 Oct, 19:005,958 MW6,010 MW
23 Oct, 20:005,878 MW5,973 MW
23 Oct, 21:005,512 MW5,580 MW
23 Oct, 22:005,086 MW5,170 MW
23 Oct, 23:004,691 MW4,830 MW
24 Oct, 00:004,443 MW4,520 MW
24 Oct, 01:004,255 MW4,270 MW
24 Oct, 02:004,113 MW4,150 MW
24 Oct, 03:004,019 MW4,073 MW
24 Oct, 04:003,980 MW4,040 MW
24 Oct, 05:004,009 MW4,065 MW
24 Oct, 06:004,186 MW4,268 MW
24 Oct, 07:004,500 MW4,515 MW
24 Oct, 08:004,665 MW4,858 MW
24 Oct, 09:004,961 MW5,180 MW
24 Oct, 10:005,209 MW5,400 MW
24 Oct, 11:005,408 MW5,563 MW
24 Oct, 12:005,435 MW5,660 MW
24 Oct, 13:005,438 MW5,630 MW
24 Oct, 14:005,156 MW5,398 MW
24 Oct, 15:004,890 MW5,160 MW
24 Oct, 16:004,835 MW5,053 MW
24 Oct, 17:005,002 MW5,098 MW
24 Oct, 18:005,198 MW5,328 MW
24 Oct, 19:005,570 MW5,695 MW
24 Oct, 20:005,449 MW5,628 MW
24 Oct, 21:005,142 MW5,290 MW
24 Oct, 22:004,810 MW4,928 MW
24 Oct, 23:004,467 MW4,663 MW
25 Oct, 00:004,283 MWn/a
25 Oct, 01:004,105 MWn/a
25 Oct, 02:003,982 MWn/a
25 Oct, 03:003,887 MWn/a
25 Oct, 03:003,780 MWn/a
25 Oct, 04:003,736 MWn/a
25 Oct, 05:003,817 MWn/a
25 Oct, 06:004,155 MWn/a
25 Oct, 07:004,751 MWn/a
25 Oct, 08:005,290 MWn/a
25 Oct, 09:005,490 MWn/a
25 Oct, 10:005,537 MWn/a
25 Oct, 11:005,745 MWn/a
25 Oct, 12:005,537 MWn/a
25 Oct, 13:005,388 MWn/a
25 Oct, 14:004,914 MWn/a
25 Oct, 15:004,599 MWn/a
25 Oct, 16:004,728 MWn/a
25 Oct, 17:005,316 MWn/a
25 Oct, 18:005,585 MWn/a
25 Oct, 19:005,631 MWn/a
25 Oct, 20:005,471 MWn/a
25 Oct, 21:005,205 MWn/a
25 Oct, 22:004,800 MWn/a
25 Oct, 23:00n/an/a
26 Oct, 00:004,216 MW4,249 MW
26 Oct, 01:003,986 MW3,970 MW
26 Oct, 02:003,847 MW3,880 MW
26 Oct, 03:003,813 MW3,810 MW
26 Oct, 04:003,790 MW3,800 MW
26 Oct, 05:003,956 MW3,985 MW
26 Oct, 06:004,406 MW4,410 MW
26 Oct, 07:004,881 MW4,973 MW
26 Oct, 08:005,171 MW5,420 MW
26 Oct, 09:005,538 MW5,788 MW
26 Oct, 10:005,902 MW5,960 MW
26 Oct, 11:006,184 MW6,105 MW
26 Oct, 12:006,428 MW6,200 MW
26 Oct, 13:006,391 MW6,218 MW
26 Oct, 14:006,314 MW6,025 MW
26 Oct, 15:006,010 MW5,793 MW
26 Oct, 16:005,804 MW5,685 MW
26 Oct, 17:005,923 MW5,818 MW
26 Oct, 18:006,260 MW6,135 MW
26 Oct, 19:006,301 MW6,135 MW
26 Oct, 20:006,218 MW6,065 MW
26 Oct, 21:005,842 MW5,730 MW
26 Oct, 22:005,328 MW5,223 MW
26 Oct, 23:004,940 MW4,830 MW
27 Oct, 00:004,572 MW4,440 MW
27 Oct, 01:004,317 MW4,220 MW
27 Oct, 02:004,179 MW4,130 MW
27 Oct, 03:004,085 MW4,068 MW
27 Oct, 04:004,127 MW4,068 MW
27 Oct, 05:004,294 MW4,235 MW
27 Oct, 06:004,693 MW4,655 MW
27 Oct, 07:005,197 MW5,200 MW
27 Oct, 08:005,965 MW5,650 MW
27 Oct, 09:006,336 MW6,000 MW
27 Oct, 10:006,287 MW6,080 MW
27 Oct, 11:006,443 MW6,140 MW
27 Oct, 12:006,685 MW6,220 MW
27 Oct, 13:006,777 MW6,180 MW
27 Oct, 14:006,518 MW5,980 MW
27 Oct, 15:006,076 MW5,760 MW
27 Oct, 16:005,762 MW5,690 MW
27 Oct, 17:005,809 MW5,931 MW
27 Oct, 18:006,244 MW6,351 MW
27 Oct, 19:006,299 MW6,370 MW
27 Oct, 20:006,251 MW6,290 MW
27 Oct, 21:005,860 MW5,920 MW
27 Oct, 22:005,342 MW5,420 MW
27 Oct, 23:004,979 MW5,030 MW
28 Oct, 00:004,682 MW4,597 MW
28 Oct, 01:004,338 MW4,303 MW
28 Oct, 02:004,175 MW4,178 MW
28 Oct, 03:004,061 MW4,090 MW
28 Oct, 04:004,033 MW4,050 MW
28 Oct, 05:004,049 MW4,108 MW
28 Oct, 06:004,148 MW4,233 MW
28 Oct, 07:004,340 MW4,425 MW
28 Oct, 08:004,899 MW4,793 MW
28 Oct, 09:005,604 MW5,188 MW
28 Oct, 10:005,954 MW5,433 MW
28 Oct, 11:005,591 MW5,590 MW
28 Oct, 12:005,551 MW5,730 MW
28 Oct, 13:005,556 MW5,690 MW

Assumptions

  • Only hours with both a forecast and a positive demand reading count (661 of 686 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.
Cite this page
APA 7

World Power Monitor. (2026). Greece Demand Forecast Accuracy: Error, Bias and Worst Miss. https://worldpowermonitor.com/forecast-accuracy/gr/

Plain text

World Power Monitor. Greece Demand Forecast Accuracy: Error, Bias and Worst Miss. Data as of 2026-10-28. Data from ENTSO-E Transparency Platform. https://worldpowermonitor.com/forecast-accuracy/gr/

BibTeX 
@misc{wpm_forecast_accuracy_gr_2026,
  title = {{Greece Demand Forecast Accuracy: Error, Bias and Worst Miss}},
  author = {{World Power Monitor}},
  year = {2026},
  note = {Data as of 2026-10-28. Data from ENTSO-E Transparency Platform.},
  url = {https://worldpowermonitor.com/forecast-accuracy/gr/}
}

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