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Data as of 2026-09-19
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Built 2026-09-21 (21 September 2026)

SC Demand Forecast Accuracy: Error, Bias and Worst Miss, 21 August to 19 September 2026

The day-ahead demand forecast for SC was off by 4.8% on average (mean absolute percentage error) over 671 hours from 21 August to 19 September 2026, and 66% of hours landed within 5% of the reading. Its bias was +3.6%: it ran high on average, an over forecast. The largest miss was 3,274 MW (298.7%) too high at 15 Sept 2026, 15:00 EDT (UTC-04:00). Dates and times are local (America/New_York).

Key Facts

  • The day-ahead demand forecast for SC was off by 4.8% on average (mean absolute percentage error) over 671 hours from 21 August to 19 September 2026, and 66% of hours landed within 5% of the reading. Its bias was +3.6%: it ran high on average, an over forecast. The largest miss was 3,274 MW (298.7%) too high at 15 Sept 2026, 15:00 EDT (UTC-04:00).
  • Across 53 US grids ranked by average error over their own latest 30 day windows, SC came 31 (1 is the smallest error).
  • On average the forecast differed from reported demand by 161 MW, against average demand of 3,669 MW.
  • The forecast was above reported demand in 73% of compared hours.

Forecast Error at a Glance

671 hours from 21 August to 19 September 2026
Average error4.8%
Bias+3.6%
Hours within 5%66%
Worst miss3,274 MW

Average error is the mean absolute percentage gap between the forecast and reported demand. Bias is the signed mean (+108 MW per hour on average): the forecast ran high on average, an over forecast. The worst miss was 3,274 MW (298.7%) too high at 15 Sept 2026, 15:00 EDT (UTC-04:00): forecast 4,370 MW, reported 1,096 MW.

Source: U.S. Energy Information Administration (EIA). (US Government work, public domain) Data as of 2026-09-19. 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 19 Sept 2026, 23:00 EDT (UTC-04:00)
SC day-ahead demand forecast and reported demand by hour Hourly reported demand and the day-ahead forecast for SC over the last 7 days of the window, to 19 Sept 2026, 23:00 EDT (UTC-04:00). Gaps are hours with a missing, zero or implausible report. 0 1,250 2,500 3,750 5,000 13 Sept, 00:0014 Sept, 00:0015 Sept, 00:0016 Sept, 00:0017 Sept, 00:0018 Sept, 00:0019 Sept, 00:00
Hourly reported demand and the day-ahead forecast for SC over the last 7 days of the window, to 19 Sept 2026, 23:00 EDT (UTC-04:00). Gaps are hours with a missing, zero or implausible report.
Data to 2026-09-19
SC day-ahead demand forecast and reported demand by hour
Local hourReported demandDay-ahead forecast
13 Sept, 00:003,363 MW3,489 MW
13 Sept, 01:003,222 MW3,380 MW
13 Sept, 02:003,087 MW3,247 MW
13 Sept, 03:003,043 MW3,131 MW
13 Sept, 04:003,004 MW3,097 MW
13 Sept, 05:002,981 MW3,037 MW
13 Sept, 06:003,016 MW3,055 MW
13 Sept, 07:003,059 MW3,119 MW
13 Sept, 08:003,257 MW3,292 MW
13 Sept, 09:003,483 MW3,506 MW
13 Sept, 10:003,715 MW3,692 MW
13 Sept, 11:003,983 MW3,789 MW
13 Sept, 12:004,205 MW3,991 MW
13 Sept, 13:004,411 MW4,115 MW
13 Sept, 14:004,608 MW4,192 MW
13 Sept, 15:004,612 MW4,203 MW
13 Sept, 16:004,627 MW4,336 MW
13 Sept, 17:004,657 MW4,363 MW
13 Sept, 18:004,639 MW4,282 MW
13 Sept, 19:004,422 MW4,241 MW
13 Sept, 20:004,219 MW4,209 MW
13 Sept, 21:003,977 MW4,122 MW
13 Sept, 22:003,770 MW3,887 MW
13 Sept, 23:003,542 MW3,681 MW
14 Sept, 00:003,324 MW3,497 MW
14 Sept, 01:003,136 MW3,374 MW
14 Sept, 02:003,012 MW3,211 MW
14 Sept, 03:003,056 MW3,115 MW
14 Sept, 04:003,012 MW3,068 MW
14 Sept, 05:003,078 MW3,078 MW
14 Sept, 06:003,175 MW3,206 MW
14 Sept, 07:003,213 MW3,268 MW
14 Sept, 08:003,347 MW3,337 MW
14 Sept, 09:003,590 MW3,532 MW
14 Sept, 10:003,765 MW3,834 MW
14 Sept, 11:004,098 MW4,168 MW
14 Sept, 12:004,376 MW4,437 MW
14 Sept, 13:004,538 MW4,643 MW
14 Sept, 14:004,664 MW4,765 MW
14 Sept, 15:004,635 MW4,824 MW
14 Sept, 16:004,678 MW4,885 MW
14 Sept, 17:004,656 MW4,899 MW
14 Sept, 18:004,643 MW4,882 MW
14 Sept, 19:004,468 MW4,809 MW
14 Sept, 20:004,289 MW4,705 MW
14 Sept, 21:004,017 MW4,578 MW
14 Sept, 22:003,808 MW4,240 MW
14 Sept, 23:003,553 MW3,932 MW
15 Sept, 00:003,378 MW3,740 MW
15 Sept, 01:003,178 MW3,486 MW
15 Sept, 02:003,035 MW3,314 MW
15 Sept, 03:003,048 MW3,201 MW
15 Sept, 04:003,014 MW3,156 MW
15 Sept, 05:003,113 MW3,120 MW
15 Sept, 06:003,231 MW3,269 MW
15 Sept, 07:003,274 MW3,331 MW
15 Sept, 08:003,381 MW3,380 MW
15 Sept, 09:003,554 MW3,472 MW
15 Sept, 10:003,715 MW3,649 MW
15 Sept, 11:003,862 MW3,861 MW
15 Sept, 12:004,059 MW4,066 MW
15 Sept, 13:004,178 MW4,199 MW
15 Sept, 14:004,302 MW4,319 MW
15 Sept, 15:001,096 MW4,370 MW
15 Sept, 16:00n/a4,401 MW
15 Sept, 17:004,261 MW4,404 MW
15 Sept, 18:004,233 MW4,369 MW
15 Sept, 19:004,070 MW4,270 MW
15 Sept, 20:003,927 MW4,141 MW
15 Sept, 21:003,726 MW4,018 MW
15 Sept, 22:003,486 MW3,718 MW
15 Sept, 23:003,202 MW3,472 MW
16 Sept, 00:003,007 MW3,294 MW
16 Sept, 01:002,878 MW3,113 MW
16 Sept, 02:002,725 MW2,979 MW
16 Sept, 03:002,697 MW2,893 MW
16 Sept, 04:002,705 MW2,824 MW
16 Sept, 05:002,766 MW2,822 MW
16 Sept, 06:002,893 MW2,948 MW
16 Sept, 07:002,928 MW2,974 MW
16 Sept, 08:002,973 MW3,024 MW
16 Sept, 09:003,221 MW3,134 MW
16 Sept, 10:003,349 MW3,274 MW
16 Sept, 11:003,616 MW3,491 MW
16 Sept, 12:003,837 MW3,717 MW
16 Sept, 13:003,950 MW3,918 MW
16 Sept, 14:004,164 MW4,105 MW
16 Sept, 15:004,290 MW4,216 MW
16 Sept, 16:004,332 MW4,278 MW
16 Sept, 17:004,338 MW4,286 MW
16 Sept, 18:004,219 MW4,268 MW
16 Sept, 19:003,974 MW4,193 MW
16 Sept, 20:003,836 MW4,034 MW
16 Sept, 21:003,613 MW3,903 MW
16 Sept, 22:003,349 MW3,633 MW
16 Sept, 23:003,358 MW3,386 MW
17 Sept, 00:002,733 MW3,209 MW
17 Sept, 01:002,783 MW3,063 MW
17 Sept, 02:002,687 MW2,916 MW
17 Sept, 03:002,633 MW2,803 MW
17 Sept, 04:002,624 MW2,756 MW
17 Sept, 05:002,710 MW2,775 MW
17 Sept, 06:002,849 MW2,891 MW
17 Sept, 07:002,792 MW2,938 MW
17 Sept, 08:002,904 MW2,991 MW
17 Sept, 09:003,090 MW3,109 MW
17 Sept, 10:003,302 MW3,261 MW
17 Sept, 11:003,453 MW3,490 MW
17 Sept, 12:003,792 MW3,755 MW
17 Sept, 13:004,062 MW3,979 MW
17 Sept, 14:004,244 MW4,193 MW
17 Sept, 15:004,305 MW4,303 MW
17 Sept, 16:004,419 MW4,403 MW
17 Sept, 17:004,405 MW4,424 MW
17 Sept, 18:004,280 MW4,402 MW
17 Sept, 19:004,089 MW4,336 MW
17 Sept, 20:003,888 MW4,145 MW
17 Sept, 21:003,700 MW4,017 MW
17 Sept, 22:00n/a3,760 MW
17 Sept, 23:00n/a3,510 MW
18 Sept, 00:003,007 MW3,303 MW
18 Sept, 01:002,902 MW3,086 MW
18 Sept, 02:002,765 MW2,952 MW
18 Sept, 03:002,753 MW2,845 MW
18 Sept, 04:002,726 MW2,788 MW
18 Sept, 05:002,836 MW2,805 MW
18 Sept, 06:002,919 MW2,919 MW
18 Sept, 07:002,994 MW2,988 MW
18 Sept, 08:003,122 MW3,077 MW
18 Sept, 09:003,301 MW3,241 MW
18 Sept, 10:003,408 MW3,452 MW
18 Sept, 11:003,631 MW3,739 MW
18 Sept, 12:003,908 MW4,051 MW
18 Sept, 13:004,140 MW4,306 MW
18 Sept, 14:004,344 MW4,501 MW
18 Sept, 15:004,485 MW4,585 MW
18 Sept, 16:004,594 MW4,672 MW
18 Sept, 17:004,623 MW4,697 MW
18 Sept, 18:004,486 MW4,675 MW
18 Sept, 19:004,296 MW4,579 MW
18 Sept, 20:004,095 MW4,416 MW
18 Sept, 21:003,884 MW4,243 MW
18 Sept, 22:003,668 MW3,970 MW
18 Sept, 23:003,479 MW3,727 MW
19 Sept, 00:003,304 MW3,513 MW
19 Sept, 01:003,119 MW3,292 MW
19 Sept, 02:003,005 MW3,130 MW
19 Sept, 03:002,931 MW3,026 MW
19 Sept, 04:002,919 MW2,969 MW
19 Sept, 05:002,900 MW2,941 MW
19 Sept, 06:002,871 MW2,972 MW
19 Sept, 07:002,953 MW3,015 MW
19 Sept, 08:003,134 MW3,136 MW
19 Sept, 09:003,426 MW3,357 MW
19 Sept, 10:003,673 MW3,569 MW
19 Sept, 11:003,900 MW3,807 MW
19 Sept, 12:004,125 MW4,005 MW
19 Sept, 13:004,354 MW4,153 MW
19 Sept, 14:004,498 MW4,278 MW
19 Sept, 15:004,388 MW4,329 MW
19 Sept, 16:004,418 MW4,340 MW
19 Sept, 17:004,157 MW4,328 MW
19 Sept, 18:004,125 MW4,255 MW
19 Sept, 19:003,872 MW4,180 MW
19 Sept, 20:003,752 MW4,073 MW
19 Sept, 21:003,705 MW3,937 MW
19 Sept, 22:003,780 MW3,741 MW
19 Sept, 23:003,628 MW3,561 MW

Assumptions

  • Only hours with both a forecast and a positive demand reading count (671 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.