Statistics
Page built 2026-09-21
Data as of 2026-09-20
Search
Built 2026-09-21 (21 September 2026)

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

The day-ahead demand forecast for TVA was off by 2.2% on average (mean absolute percentage error) over 719 hours from 21 August to 20 September 2026, and 94% of hours landed within 5% of the reading. Its bias was +1.0%: it ran high on average, an over forecast. The largest miss was 4,310 MW (17.1%) too high at 26 Aug 2026, 16:00 CDT (UTC-05:00). Dates and times are local (America/Chicago).

Key Facts

  • The day-ahead demand forecast for TVA was off by 2.2% on average (mean absolute percentage error) over 719 hours from 21 August to 20 September 2026, and 94% of hours landed within 5% of the reading. Its bias was +1.0%: it ran high on average, an over forecast. The largest miss was 4,310 MW (17.1%) too high at 26 Aug 2026, 16:00 CDT (UTC-05:00).
  • Across 53 US grids ranked by average error over their own latest 30 day windows, TVA came 9 (1 is the smallest error).
  • On average the forecast differed from reported demand by 522 MW, against average demand of 23,465 MW.
  • The forecast was above reported demand in 65% of compared hours.

Forecast Error at a Glance

719 hours from 21 August to 20 September 2026
Average error2.2%
Bias+1.0%
Hours within 5%94%
Worst miss4,310 MW

Average error is the mean absolute percentage gap between the forecast and reported demand. Bias is the signed mean (+253 MW per hour on average): the forecast ran high on average, an over forecast. The worst miss was 4,310 MW (17.1%) too high at 26 Aug 2026, 16:00 CDT (UTC-05:00): forecast 29,476 MW, reported 25,166 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, 20:00 CDT (UTC-05:00)
TVA day-ahead demand forecast and reported demand by hour Hourly reported demand and the day-ahead forecast for TVA over the last 7 days of the window, to 20 Sept 2026, 20:00 CDT (UTC-05:00). Gaps are hours with a missing, zero or implausible report. 0 10,000 20,000 30,000 40,000 13 Sept, 21:0014 Sept, 21:0015 Sept, 21:0016 Sept, 21:0017 Sept, 21:0018 Sept, 21:0019 Sept, 21:00
Hourly reported demand and the day-ahead forecast for TVA over the last 7 days of the window, to 20 Sept 2026, 20:00 CDT (UTC-05:00). Gaps are hours with a missing, zero or implausible report.
Data to 2026-09-20
TVA day-ahead demand forecast and reported demand by hour
Local hourReported demandDay-ahead forecast
13 Sept, 21:0023,775 MW23,592 MW
13 Sept, 22:0021,987 MW21,864 MW
13 Sept, 23:0020,525 MW20,411 MW
14 Sept, 00:0019,245 MW19,830 MW
14 Sept, 01:0018,296 MW18,953 MW
14 Sept, 02:0017,757 MW18,346 MW
14 Sept, 03:0017,371 MW17,956 MW
14 Sept, 04:0017,587 MW18,030 MW
14 Sept, 05:0018,501 MW18,881 MW
14 Sept, 06:0019,236 MW19,710 MW
14 Sept, 07:0019,963 MW20,512 MW
14 Sept, 08:0021,218 MW21,765 MW
14 Sept, 09:0022,974 MW23,533 MW
14 Sept, 10:0024,994 MW25,853 MW
14 Sept, 11:0026,949 MW27,788 MW
14 Sept, 12:0028,719 MW29,423 MW
14 Sept, 13:0029,624 MW30,512 MW
14 Sept, 14:0030,047 MW31,161 MW
14 Sept, 15:0030,100 MW31,632 MW
14 Sept, 16:0030,047 MW31,592 MW
14 Sept, 17:0029,493 MW30,885 MW
14 Sept, 18:0028,191 MW29,776 MW
14 Sept, 19:0027,465 MW28,782 MW
14 Sept, 20:0026,151 MW27,496 MW
14 Sept, 21:0024,335 MW25,733 MW
14 Sept, 22:0022,476 MW23,841 MW
14 Sept, 23:0020,874 MW22,176 MW
15 Sept, 00:0019,570 MW20,112 MW
15 Sept, 01:0018,504 MW19,157 MW
15 Sept, 02:0017,961 MW18,471 MW
15 Sept, 03:0017,366 MW18,153 MW
15 Sept, 04:0017,637 MW18,149 MW
15 Sept, 05:0018,337 MW18,935 MW
15 Sept, 06:0019,012 MW19,718 MW
15 Sept, 07:0019,748 MW20,527 MW
15 Sept, 08:0021,247 MW21,760 MW
15 Sept, 09:0023,285 MW23,700 MW
15 Sept, 10:0025,696 MW26,165 MW
15 Sept, 11:0027,848 MW28,471 MW
15 Sept, 12:0029,625 MW30,108 MW
15 Sept, 13:0030,629 MW31,125 MW
15 Sept, 14:0031,233 MW32,013 MW
15 Sept, 15:0031,665 MW32,438 MW
15 Sept, 16:0031,721 MW32,317 MW
15 Sept, 17:0031,184 MW31,639 MW
15 Sept, 18:0029,812 MW30,171 MW
15 Sept, 19:0028,800 MW29,320 MW
15 Sept, 20:0027,072 MW28,063 MW
15 Sept, 21:0025,221 MW26,331 MW
15 Sept, 22:0023,356 MW24,486 MW
15 Sept, 23:0021,854 MW22,674 MW
16 Sept, 00:0020,566 MW21,156 MW
16 Sept, 01:0019,509 MW20,143 MW
16 Sept, 02:0018,686 MW19,433 MW
16 Sept, 03:0018,319 MW18,898 MW
16 Sept, 04:0018,259 MW18,931 MW
16 Sept, 05:0019,017 MW19,627 MW
16 Sept, 06:0019,765 MW20,345 MW
16 Sept, 07:0020,399 MW20,993 MW
16 Sept, 08:0021,720 MW22,194 MW
16 Sept, 09:0023,540 MW24,026 MW
16 Sept, 10:0025,488 MW26,232 MW
16 Sept, 11:0027,557 MW28,340 MW
16 Sept, 12:0029,085 MW29,894 MW
16 Sept, 13:0030,029 MW31,017 MW
16 Sept, 14:0030,632 MW31,750 MW
16 Sept, 15:0031,062 MW32,240 MW
16 Sept, 16:0030,928 MW32,339 MW
16 Sept, 17:0030,314 MW31,593 MW
16 Sept, 18:0029,016 MW30,137 MW
16 Sept, 19:0028,163 MW29,194 MW
16 Sept, 20:0026,830 MW27,946 MW
16 Sept, 21:0025,048 MW26,140 MW
16 Sept, 22:0023,214 MW24,367 MW
16 Sept, 23:0021,547 MW22,588 MW
17 Sept, 00:0020,221 MW20,905 MW
17 Sept, 01:0019,436 MW19,824 MW
17 Sept, 02:0018,714 MW19,045 MW
17 Sept, 03:0018,246 MW18,537 MW
17 Sept, 04:0018,304 MW18,482 MW
17 Sept, 05:0018,798 MW19,187 MW
17 Sept, 06:0019,476 MW19,954 MW
17 Sept, 07:0020,035 MW20,714 MW
17 Sept, 08:0021,490 MW22,000 MW
17 Sept, 09:0023,500 MW23,902 MW
17 Sept, 10:0025,642 MW26,294 MW
17 Sept, 11:0027,601 MW28,491 MW
17 Sept, 12:0029,319 MW30,010 MW
17 Sept, 13:0029,964 MW31,087 MW
17 Sept, 14:0030,573 MW32,004 MW
17 Sept, 15:0030,632 MW32,411 MW
17 Sept, 16:0030,695 MW32,486 MW
17 Sept, 17:0030,172 MW31,679 MW
17 Sept, 18:0028,939 MW30,290 MW
17 Sept, 19:0028,443 MW29,346 MW
17 Sept, 20:0026,969 MW27,929 MW
17 Sept, 21:0024,867 MW26,104 MW
17 Sept, 22:0023,173 MW24,337 MW
17 Sept, 23:0021,130 MW22,598 MW
18 Sept, 00:0020,326 MW21,164 MW
18 Sept, 01:0019,320 MW20,075 MW
18 Sept, 02:0018,574 MW19,391 MW
18 Sept, 03:0018,075 MW18,879 MW
18 Sept, 04:0018,099 MW18,783 MW
18 Sept, 05:0018,857 MW19,532 MW
18 Sept, 06:0019,569 MW20,234 MW
18 Sept, 07:0020,070 MW20,895 MW
18 Sept, 08:0021,415 MW22,294 MW
18 Sept, 09:0023,584 MW24,291 MW
18 Sept, 10:0026,025 MW26,679 MW
18 Sept, 11:0028,441 MW28,944 MW
18 Sept, 12:0030,009 MW30,442 MW
18 Sept, 13:0030,836 MW31,391 MW
18 Sept, 14:0031,369 MW32,231 MW
18 Sept, 15:0031,277 MW32,415 MW
18 Sept, 16:0031,143 MW32,256 MW
18 Sept, 17:0030,346 MW31,352 MW
18 Sept, 18:0028,685 MW29,805 MW
18 Sept, 19:0027,610 MW28,747 MW
18 Sept, 20:0026,084 MW27,435 MW
18 Sept, 21:0024,563 MW25,655 MW
18 Sept, 22:0023,042 MW24,102 MW
18 Sept, 23:0021,497 MW22,411 MW
19 Sept, 00:0020,179 MW20,928 MW
19 Sept, 01:0019,130 MW19,864 MW
19 Sept, 02:0018,068 MW18,965 MW
19 Sept, 03:0017,665 MW18,458 MW
19 Sept, 04:0017,623 MW18,080 MW
19 Sept, 05:0017,578 MW18,090 MW
19 Sept, 06:0017,555 MW18,186 MW
19 Sept, 07:0018,211 MW18,831 MW
19 Sept, 08:0020,015 MW20,338 MW
19 Sept, 09:0022,198 MW22,583 MW
19 Sept, 10:0024,566 MW25,077 MW
19 Sept, 11:0026,892 MW27,483 MW
19 Sept, 12:0028,633 MW29,236 MW
19 Sept, 13:0029,503 MW30,503 MW
19 Sept, 14:0029,649 MW31,161 MW
19 Sept, 15:0029,837 MW31,362 MW
19 Sept, 16:0029,596 MW30,967 MW
19 Sept, 17:0028,869 MW30,312 MW
19 Sept, 18:0027,497 MW28,754 MW
19 Sept, 19:0026,207 MW27,792 MW
19 Sept, 20:0024,840 MW26,537 MW
19 Sept, 21:0023,349 MW24,670 MW
19 Sept, 22:0021,902 MW23,210 MW
19 Sept, 23:0020,573 MW21,885 MW
20 Sept, 00:0019,482 MW19,701 MW
20 Sept, 01:0018,549 MW18,692 MW
20 Sept, 02:0017,887 MW17,880 MW
20 Sept, 03:0017,245 MW17,354 MW
20 Sept, 04:0016,924 MW17,030 MW
20 Sept, 05:0016,990 MW17,062 MW
20 Sept, 06:0017,229 MW17,140 MW
20 Sept, 07:0017,811 MW17,829 MW
20 Sept, 08:0019,389 MW19,463 MW
20 Sept, 09:0021,344 MW21,329 MW
20 Sept, 10:0023,242 MW23,618 MW
20 Sept, 11:0025,274 MW25,890 MW
20 Sept, 12:0027,340 MW27,439 MW
20 Sept, 13:0028,845 MW28,732 MW
20 Sept, 14:0029,758 MW29,606 MW
20 Sept, 15:0030,252 MW30,251 MW
20 Sept, 16:0030,252 MW30,423 MW
20 Sept, 17:0029,755 MW29,964 MW
20 Sept, 18:0029,755 MW28,600 MW
20 Sept, 19:0027,211 MW27,571 MW
20 Sept, 20:0027,211 MW26,008 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.