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Data as of 2026-09-20
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Built 2026-09-21 (21 September 2026)

FMPP Demand Forecast Accuracy: Error, Bias and Worst Miss, 21 August to 20 September 2026

The day-ahead demand forecast for FMPP was off by 4.4% on average (mean absolute percentage error) over 719 hours from 21 August to 20 September 2026, and 67% of hours landed within 5% of the reading. Its bias was +2.5%: it ran high on average, an over forecast. The largest miss was 688 MW (27.8%) too high at 23 Aug 2026, 17:00 EDT (UTC-04:00). Dates and times are local (America/New_York).

Key Facts

  • The day-ahead demand forecast for FMPP was off by 4.4% on average (mean absolute percentage error) over 719 hours from 21 August to 20 September 2026, and 67% of hours landed within 5% of the reading. Its bias was +2.5%: it ran high on average, an over forecast. The largest miss was 688 MW (27.8%) too high at 23 Aug 2026, 17:00 EDT (UTC-04:00).
  • Across 53 US grids ranked by average error over their own latest 30 day windows, FMPP came 30 (1 is the smallest error).
  • On average the forecast differed from reported demand by 114 MW, against average demand of 2,531 MW.
  • The forecast was above reported demand in 67% of compared hours.

Forecast Error at a Glance

719 hours from 21 August to 20 September 2026
Average error4.4%
Bias+2.5%
Hours within 5%67%
Worst miss688 MW

Average error is the mean absolute percentage gap between the forecast and reported demand. Bias is the signed mean (+69 MW per hour on average): the forecast ran high on average, an over forecast. The worst miss was 688 MW (27.8%) too high at 23 Aug 2026, 17:00 EDT (UTC-04:00): forecast 3,164 MW, reported 2,476 MW.

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)
FMPP day-ahead demand forecast and reported demand by hour Hourly reported demand and the day-ahead forecast for FMPP over the last 7 days of the window, to 20 Sept 2026, 21:00 EDT (UTC-04:00). Gaps are hours with a missing, zero or implausible report. 0 1,000 2,000 3,000 4,000 13 Sept, 22:0014 Sept, 22:0015 Sept, 22:0016 Sept, 22:0017 Sept, 22:0018 Sept, 22:0019 Sept, 22:00
Hourly reported demand and the day-ahead forecast for FMPP over the last 7 days of the window, to 20 Sept 2026, 21:00 EDT (UTC-04:00). Gaps are hours with a missing, zero or implausible report.
Data to 2026-09-20
FMPP day-ahead demand forecast and reported demand by hour
Local hourReported demandDay-ahead forecast
13 Sept, 22:002,571 MW2,449 MW
13 Sept, 23:002,360 MW2,248 MW
14 Sept, 00:002,196 MW2,100 MW
14 Sept, 01:002,080 MW1,996 MW
14 Sept, 02:001,984 MW1,923 MW
14 Sept, 03:001,928 MW1,896 MW
14 Sept, 04:001,933 MW1,934 MW
14 Sept, 05:002,011 MW2,039 MW
14 Sept, 06:002,124 MW2,151 MW
14 Sept, 07:002,197 MW2,222 MW
14 Sept, 08:002,329 MW2,409 MW
14 Sept, 09:002,557 MW2,633 MW
14 Sept, 10:002,775 MW2,853 MW
14 Sept, 11:002,952 MW3,064 MW
14 Sept, 12:003,060 MW3,327 MW
14 Sept, 13:003,173 MW3,438 MW
14 Sept, 14:003,222 MW3,527 MW
14 Sept, 15:003,289 MW3,500 MW
14 Sept, 16:003,369 MW3,441 MW
14 Sept, 17:003,276 MW3,304 MW
14 Sept, 18:003,094 MW3,208 MW
14 Sept, 19:003,023 MW3,102 MW
14 Sept, 20:003,002 MW2,944 MW
14 Sept, 21:002,865 MW2,741 MW
14 Sept, 22:002,654 MW2,519 MW
14 Sept, 23:002,425 MW2,308 MW
15 Sept, 00:002,246 MW2,151 MW
15 Sept, 01:002,124 MW2,036 MW
15 Sept, 02:002,026 MW1,969 MW
15 Sept, 03:001,982 MW1,936 MW
15 Sept, 04:001,974 MW1,965 MW
15 Sept, 05:002,077 MW2,080 MW
15 Sept, 06:002,192 MW2,182 MW
15 Sept, 07:002,242 MW2,256 MW
15 Sept, 08:002,372 MW2,438 MW
15 Sept, 09:002,547 MW2,654 MW
15 Sept, 10:002,777 MW2,868 MW
15 Sept, 11:002,976 MW3,036 MW
15 Sept, 12:003,094 MW3,248 MW
15 Sept, 13:003,039 MW3,318 MW
15 Sept, 14:002,921 MW3,367 MW
15 Sept, 15:002,856 MW3,380 MW
15 Sept, 16:002,944 MW3,356 MW
15 Sept, 17:002,957 MW3,180 MW
15 Sept, 18:002,875 MW3,050 MW
15 Sept, 19:002,814 MW2,977 MW
15 Sept, 20:002,841 MW2,878 MW
15 Sept, 21:002,766 MW2,710 MW
15 Sept, 22:002,573 MW2,484 MW
15 Sept, 23:002,364 MW2,293 MW
16 Sept, 00:002,190 MW2,246 MW
16 Sept, 01:002,068 MW2,129 MW
16 Sept, 02:001,994 MW2,055 MW
16 Sept, 03:001,953 MW2,027 MW
16 Sept, 04:001,961 MW2,060 MW
16 Sept, 05:002,060 MW2,205 MW
16 Sept, 06:002,195 MW2,304 MW
16 Sept, 07:002,240 MW2,382 MW
16 Sept, 08:002,316 MW2,532 MW
16 Sept, 09:002,460 MW2,712 MW
16 Sept, 10:002,624 MW2,890 MW
16 Sept, 11:002,761 MW3,024 MW
16 Sept, 12:002,935 MW3,020 MW
16 Sept, 13:003,058 MW3,114 MW
16 Sept, 14:003,116 MW3,215 MW
16 Sept, 15:003,157 MW3,289 MW
16 Sept, 16:003,192 MW3,276 MW
16 Sept, 17:003,168 MW3,270 MW
16 Sept, 18:003,078 MW3,152 MW
16 Sept, 19:002,952 MW3,052 MW
16 Sept, 20:002,938 MW2,919 MW
16 Sept, 21:002,772 MW2,699 MW
16 Sept, 22:002,550 MW2,465 MW
16 Sept, 23:002,322 MW2,257 MW
17 Sept, 00:002,141 MW2,062 MW
17 Sept, 01:002,011 MW1,962 MW
17 Sept, 02:001,926 MW1,898 MW
17 Sept, 03:001,876 MW1,881 MW
17 Sept, 04:001,897 MW1,918 MW
17 Sept, 05:001,976 MW2,048 MW
17 Sept, 06:002,116 MW2,166 MW
17 Sept, 07:002,161 MW2,249 MW
17 Sept, 08:002,266 MW2,400 MW
17 Sept, 09:002,418 MW2,557 MW
17 Sept, 10:002,595 MW2,722 MW
17 Sept, 11:002,759 MW2,869 MW
17 Sept, 12:002,909 MW2,986 MW
17 Sept, 13:002,999 MW3,076 MW
17 Sept, 14:003,007 MW3,139 MW
17 Sept, 15:003,057 MW3,184 MW
17 Sept, 16:003,100 MW3,200 MW
17 Sept, 17:003,101 MW3,137 MW
17 Sept, 18:003,012 MW3,025 MW
17 Sept, 19:002,918 MW2,945 MW
17 Sept, 20:002,848 MW2,817 MW
17 Sept, 21:002,657 MW2,613 MW
17 Sept, 22:002,451 MW2,397 MW
17 Sept, 23:002,246 MW2,183 MW
18 Sept, 00:002,072 MW2,047 MW
18 Sept, 01:001,952 MW1,954 MW
18 Sept, 02:001,881 MW1,878 MW
18 Sept, 03:001,827 MW1,856 MW
18 Sept, 04:001,834 MW1,896 MW
18 Sept, 05:001,914 MW2,001 MW
18 Sept, 06:002,049 MW2,113 MW
18 Sept, 07:002,117 MW2,199 MW
18 Sept, 08:002,211 MW2,342 MW
18 Sept, 09:002,371 MW2,535 MW
18 Sept, 10:002,607 MW2,742 MW
18 Sept, 11:002,649 MW2,896 MW
18 Sept, 12:002,810 MW3,024 MW
18 Sept, 13:002,897 MW3,125 MW
18 Sept, 14:002,920 MW3,196 MW
18 Sept, 15:002,976 MW3,231 MW
18 Sept, 16:002,978 MW3,210 MW
18 Sept, 17:002,934 MW3,123 MW
18 Sept, 18:002,859 MW2,974 MW
18 Sept, 19:002,732 MW2,855 MW
18 Sept, 20:002,710 MW2,731 MW
18 Sept, 21:002,586 MW2,564 MW
18 Sept, 22:002,406 MW2,365 MW
18 Sept, 23:002,232 MW2,188 MW
19 Sept, 00:002,056 MW2,023 MW
19 Sept, 01:001,926 MW1,918 MW
19 Sept, 02:001,823 MW1,831 MW
19 Sept, 03:001,759 MW1,787 MW
19 Sept, 04:001,721 MW1,790 MW
19 Sept, 05:001,734 MW1,823 MW
19 Sept, 06:001,784 MW1,870 MW
19 Sept, 07:001,826 MW1,956 MW
19 Sept, 08:001,986 MW2,129 MW
19 Sept, 09:002,190 MW2,365 MW
19 Sept, 10:002,422 MW2,591 MW
19 Sept, 11:002,647 MW2,755 MW
19 Sept, 12:002,762 MW2,905 MW
19 Sept, 13:002,870 MW2,972 MW
19 Sept, 14:002,841 MW3,018 MW
19 Sept, 15:002,788 MW3,019 MW
19 Sept, 16:002,731 MW2,988 MW
19 Sept, 17:002,676 MW2,896 MW
19 Sept, 18:002,681 MW2,781 MW
19 Sept, 19:002,667 MW2,694 MW
19 Sept, 20:002,653 MW2,590 MW
19 Sept, 21:002,531 MW2,430 MW
19 Sept, 22:002,377 MW2,250 MW
19 Sept, 23:002,209 MW2,097 MW
20 Sept, 00:002,075 MW1,961 MW
20 Sept, 01:001,939 MW1,864 MW
20 Sept, 02:001,835 MW1,797 MW
20 Sept, 03:001,757 MW1,749 MW
20 Sept, 04:001,741 MW1,744 MW
20 Sept, 05:001,721 MW1,773 MW
20 Sept, 06:001,759 MW1,806 MW
20 Sept, 07:001,790 MW1,907 MW
20 Sept, 08:001,956 MW2,072 MW
20 Sept, 09:002,209 MW2,294 MW
20 Sept, 10:002,417 MW2,522 MW
20 Sept, 11:002,633 MW2,717 MW
20 Sept, 12:002,808 MW2,856 MW
20 Sept, 13:002,908 MW2,942 MW
20 Sept, 14:002,904 MW2,989 MW
20 Sept, 15:002,929 MW3,004 MW
20 Sept, 16:002,899 MW2,937 MW
20 Sept, 17:002,826 MW2,854 MW
20 Sept, 18:002,723 MW2,753 MW
20 Sept, 19:002,662 MW2,685 MW
20 Sept, 20:002,605 MW2,594 MW
20 Sept, 21:002,469 MW2,454 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.