Italy Sardinia Demand Forecast Accuracy: Error, Bias and Worst Miss, 23 August to 20 September 2026
The day-ahead demand forecast for Italy Sardinia was off by 5.9% on average (mean absolute percentage error) over 686 hours from 23 August to 20 September 2026, and 55% of hours landed within 5% of the reading. Its bias was +3.7%: it ran high on average, an over forecast. The largest miss was 244 MW (35.3%) too high at 12 Sept 2026, 16:00 CEST (UTC+02:00). Dates and times are local (Europe/Rome).
Key Facts
- The day-ahead demand forecast for Italy Sardinia was off by 5.9% on average (mean absolute percentage error) over 686 hours from 23 August to 20 September 2026, and 55% of hours landed within 5% of the reading. Its bias was +3.7%: it ran high on average, an over forecast. The largest miss was 244 MW (35.3%) too high at 12 Sept 2026, 16:00 CEST (UTC+02:00).
- Across 47 European bidding zones ranked by average error over their own latest 30 day windows, Italy Sardinia came 35 (1 is the smallest error).
- On average the forecast differed from reported demand by 58 MW, against average demand of 1,032 MW.
- The forecast was above reported demand in 69% of compared hours.
Forecast Error at a Glance
686 hours from 23 August to 20 September 2026Average error5.9%
Bias+3.7%
Hours within 5%55%
Worst miss244 MW
Average error is the mean absolute percentage gap between the forecast and reported demand. Bias is the signed mean (+30 MW per hour on average): the forecast ran high on average, an over forecast. The worst miss was 244 MW (35.3%) too high at 12 Sept 2026, 16:00 CEST (UTC+02:00): forecast 935 MW, reported 691 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, 13:00 CEST (UTC+02:00)Data to 2026-09-20
| Local hour | Reported demand | Day-ahead forecast |
|---|---|---|
| 13 Sept, 14:00 | 563 MW | 713 MW |
| 13 Sept, 15:00 | 589 MW | 775 MW |
| 13 Sept, 16:00 | 643 MW | 840 MW |
| 13 Sept, 17:00 | 782 MW | 928 MW |
| 13 Sept, 18:00 | 904 MW | 1,003 MW |
| 13 Sept, 19:00 | 1,021 MW | 1,088 MW |
| 13 Sept, 20:00 | 1,065 MW | 1,123 MW |
| 13 Sept, 21:00 | 1,003 MW | 1,068 MW |
| 13 Sept, 22:00 | 935 MW | 995 MW |
| 13 Sept, 23:00 | 871 MW | 920 MW |
| 14 Sept, 00:00 | 811 MW | 860 MW |
| 14 Sept, 01:00 | 776 MW | 820 MW |
| 14 Sept, 02:00 | 762 MW | 790 MW |
| 14 Sept, 03:00 | 755 MW | 775 MW |
| 14 Sept, 04:00 | 750 MW | 770 MW |
| 14 Sept, 05:00 | 769 MW | 783 MW |
| 14 Sept, 06:00 | 847 MW | 875 MW |
| 14 Sept, 07:00 | 910 MW | 940 MW |
| 14 Sept, 08:00 | 916 MW | 993 MW |
| 14 Sept, 09:00 | 869 MW | 958 MW |
| 14 Sept, 10:00 | 805 MW | 883 MW |
| 14 Sept, 11:00 | 769 MW | 858 MW |
| 14 Sept, 12:00 | 761 MW | 803 MW |
| 14 Sept, 13:00 | 731 MW | 803 MW |
| 14 Sept, 14:00 | 728 MW | 803 MW |
| 14 Sept, 15:00 | 728 MW | 835 MW |
| 14 Sept, 16:00 | 787 MW | 898 MW |
| 14 Sept, 17:00 | 897 MW | 978 MW |
| 14 Sept, 18:00 | 999 MW | 1,040 MW |
| 14 Sept, 19:00 | 1,093 MW | 1,123 MW |
| 14 Sept, 20:00 | 1,109 MW | 1,160 MW |
| 14 Sept, 21:00 | 1,030 MW | 1,070 MW |
| 14 Sept, 22:00 | 946 MW | 995 MW |
| 14 Sept, 23:00 | 867 MW | 925 MW |
| 15 Sept, 00:00 | 776 MW | 835 MW |
| 15 Sept, 01:00 | 739 MW | 798 MW |
| 15 Sept, 02:00 | 733 MW | 770 MW |
| 15 Sept, 03:00 | 738 MW | 760 MW |
| 15 Sept, 04:00 | 729 MW | 763 MW |
| 15 Sept, 05:00 | 755 MW | 785 MW |
| 15 Sept, 06:00 | 853 MW | 863 MW |
| 15 Sept, 07:00 | 917 MW | 943 MW |
| 15 Sept, 08:00 | 912 MW | 980 MW |
| 15 Sept, 09:00 | 859 MW | 975 MW |
| 15 Sept, 10:00 | 806 MW | 898 MW |
| 15 Sept, 11:00 | 764 MW | 850 MW |
| 15 Sept, 12:00 | 784 MW | 815 MW |
| 15 Sept, 13:00 | 752 MW | 768 MW |
| 15 Sept, 14:00 | 725 MW | 740 MW |
| 15 Sept, 15:00 | 760 MW | 775 MW |
| 15 Sept, 16:00 | 810 MW | 835 MW |
| 15 Sept, 17:00 | 896 MW | 928 MW |
| 15 Sept, 18:00 | 997 MW | 1,008 MW |
| 15 Sept, 19:00 | 1,106 MW | 1,095 MW |
| 15 Sept, 20:00 | 1,135 MW | 1,113 MW |
| 15 Sept, 21:00 | 1,041 MW | 1,028 MW |
| 15 Sept, 22:00 | 960 MW | 953 MW |
| 15 Sept, 23:00 | 882 MW | 880 MW |
| 16 Sept, 00:00 | 818 MW | 850 MW |
| 16 Sept, 01:00 | 781 MW | 805 MW |
| 16 Sept, 02:00 | 768 MW | 788 MW |
| 16 Sept, 03:00 | 761 MW | 775 MW |
| 16 Sept, 04:00 | 758 MW | 778 MW |
| 16 Sept, 05:00 | 783 MW | 795 MW |
| 16 Sept, 06:00 | 866 MW | 873 MW |
| 16 Sept, 07:00 | 936 MW | 948 MW |
| 16 Sept, 08:00 | 937 MW | 973 MW |
| 16 Sept, 09:00 | 873 MW | 948 MW |
| 16 Sept, 10:00 | 820 MW | 900 MW |
| 16 Sept, 11:00 | 785 MW | 855 MW |
| 16 Sept, 12:00 | 765 MW | 833 MW |
| 16 Sept, 13:00 | 756 MW | 785 MW |
| 16 Sept, 14:00 | 734 MW | 790 MW |
| 16 Sept, 15:00 | 747 MW | 813 MW |
| 16 Sept, 16:00 | 809 MW | 870 MW |
| 16 Sept, 17:00 | 929 MW | 938 MW |
| 16 Sept, 18:00 | 1,033 MW | 1,008 MW |
| 16 Sept, 19:00 | 1,134 MW | 1,110 MW |
| 16 Sept, 20:00 | 1,149 MW | 1,123 MW |
| 16 Sept, 21:00 | 1,059 MW | 1,035 MW |
| 16 Sept, 22:00 | 971 MW | 960 MW |
| 16 Sept, 23:00 | 890 MW | 893 MW |
| 17 Sept, 00:00 | 828 MW | 820 MW |
| 17 Sept, 01:00 | 786 MW | 785 MW |
| 17 Sept, 02:00 | 769 MW | 780 MW |
| 17 Sept, 03:00 | 765 MW | 780 MW |
| 17 Sept, 04:00 | 765 MW | 773 MW |
| 17 Sept, 05:00 | 781 MW | 785 MW |
| 17 Sept, 06:00 | 865 MW | 863 MW |
| 17 Sept, 07:00 | 936 MW | 940 MW |
| 17 Sept, 08:00 | 939 MW | 953 MW |
| 17 Sept, 09:00 | 873 MW | 920 MW |
| 17 Sept, 10:00 | 820 MW | 868 MW |
| 17 Sept, 11:00 | 777 MW | 805 MW |
| 17 Sept, 12:00 | 803 MW | 783 MW |
| 17 Sept, 13:00 | 770 MW | 768 MW |
| 17 Sept, 14:00 | 759 MW | 768 MW |
| 17 Sept, 15:00 | 777 MW | 760 MW |
| 17 Sept, 16:00 | 830 MW | 838 MW |
| 17 Sept, 17:00 | 959 MW | 930 MW |
| 17 Sept, 18:00 | 1,079 MW | 1,028 MW |
| 17 Sept, 19:00 | 1,165 MW | 1,090 MW |
| 17 Sept, 20:00 | 1,164 MW | 1,093 MW |
| 17 Sept, 21:00 | 1,075 MW | 1,015 MW |
| 17 Sept, 22:00 | 1,003 MW | 935 MW |
| 17 Sept, 23:00 | 926 MW | 860 MW |
| 18 Sept, 00:00 | 828 MW | 833 MW |
| 18 Sept, 01:00 | 795 MW | 795 MW |
| 18 Sept, 02:00 | 773 MW | 783 MW |
| 18 Sept, 03:00 | 766 MW | 780 MW |
| 18 Sept, 04:00 | 764 MW | 780 MW |
| 18 Sept, 05:00 | 790 MW | 790 MW |
| 18 Sept, 06:00 | 870 MW | 875 MW |
| 18 Sept, 07:00 | 942 MW | 955 MW |
| 18 Sept, 08:00 | 934 MW | 980 MW |
| 18 Sept, 09:00 | 877 MW | 955 MW |
| 18 Sept, 10:00 | 826 MW | 910 MW |
| 18 Sept, 11:00 | 804 MW | 865 MW |
| 18 Sept, 12:00 | 766 MW | 828 MW |
| 18 Sept, 13:00 | 771 MW | 833 MW |
| 18 Sept, 14:00 | 793 MW | 803 MW |
| 18 Sept, 15:00 | 781 MW | 878 MW |
| 18 Sept, 16:00 | 777 MW | 958 MW |
| 18 Sept, 17:00 | 916 MW | 1,005 MW |
| 18 Sept, 18:00 | 1,034 MW | 1,033 MW |
| 18 Sept, 19:00 | 1,132 MW | 1,103 MW |
| 18 Sept, 20:00 | 1,136 MW | 1,110 MW |
| 18 Sept, 21:00 | 1,048 MW | 1,033 MW |
| 18 Sept, 22:00 | 964 MW | 953 MW |
| 18 Sept, 23:00 | 905 MW | 875 MW |
| 19 Sept, 00:00 | 822 MW | 828 MW |
| 19 Sept, 01:00 | 781 MW | 795 MW |
| 19 Sept, 02:00 | 759 MW | 785 MW |
| 19 Sept, 03:00 | 743 MW | 780 MW |
| 19 Sept, 04:00 | 746 MW | 778 MW |
| 19 Sept, 05:00 | 757 MW | 783 MW |
| 19 Sept, 06:00 | 817 MW | 830 MW |
| 19 Sept, 07:00 | 855 MW | 870 MW |
| 19 Sept, 08:00 | 857 MW | 885 MW |
| 19 Sept, 09:00 | 825 MW | 893 MW |
| 19 Sept, 10:00 | 784 MW | 840 MW |
| 19 Sept, 11:00 | 727 MW | 795 MW |
| 19 Sept, 12:00 | 736 MW | 770 MW |
| 19 Sept, 13:00 | 690 MW | 768 MW |
| 19 Sept, 14:00 | 696 MW | 765 MW |
| 19 Sept, 15:00 | 683 MW | 795 MW |
| 19 Sept, 16:00 | 707 MW | 840 MW |
| 19 Sept, 17:00 | 825 MW | 913 MW |
| 19 Sept, 18:00 | 945 MW | 1,000 MW |
| 19 Sept, 19:00 | 1,048 MW | 1,068 MW |
| 19 Sept, 20:00 | 1,053 MW | 1,065 MW |
| 19 Sept, 21:00 | 976 MW | 998 MW |
| 19 Sept, 22:00 | 910 MW | 923 MW |
| 19 Sept, 23:00 | 849 MW | 860 MW |
| 20 Sept, 00:00 | 805 MW | 815 MW |
| 20 Sept, 01:00 | 778 MW | 780 MW |
| 20 Sept, 02:00 | 753 MW | 768 MW |
| 20 Sept, 03:00 | 739 MW | 753 MW |
| 20 Sept, 04:00 | 735 MW | 753 MW |
| 20 Sept, 05:00 | 753 MW | 753 MW |
| 20 Sept, 06:00 | 787 MW | 790 MW |
| 20 Sept, 07:00 | 804 MW | 798 MW |
| 20 Sept, 08:00 | 813 MW | 818 MW |
| 20 Sept, 09:00 | 788 MW | 828 MW |
| 20 Sept, 10:00 | 789 MW | 798 MW |
| 20 Sept, 11:00 | 775 MW | 735 MW |
| 20 Sept, 12:00 | 775 MW | 748 MW |
| 20 Sept, 13:00 | 728 MW | 718 MW |
Assumptions
- Only hours with both a forecast and a positive demand reading count (686 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.