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

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

The day-ahead demand forecast for PACW was off by 2.6% on average (mean absolute percentage error) over 719 hours from 21 August to 20 September 2026, and 86% of hours landed within 5% of the reading. Its bias was +0.8%: it ran high on average, an over forecast. The largest miss was 263 MW (11.0%) too high at 9 Sept 2026, 12:00 PDT (UTC-07:00). Dates and times are local (America/Los_Angeles).

Key Facts

  • The day-ahead demand forecast for PACW was off by 2.6% on average (mean absolute percentage error) over 719 hours from 21 August to 20 September 2026, and 86% of hours landed within 5% of the reading. Its bias was +0.8%: it ran high on average, an over forecast. The largest miss was 263 MW (11.0%) too high at 9 Sept 2026, 12:00 PDT (UTC-07:00).
  • Across 53 US grids ranked by average error over their own latest 30 day windows, PACW came 13 (1 is the smallest error).
  • On average the forecast differed from reported demand by 60 MW, against average demand of 2,261 MW.
  • The forecast was above reported demand in 58% of compared hours.

Forecast Error at a Glance

719 hours from 21 August to 20 September 2026
Average error2.6%
Bias+0.8%
Hours within 5%86%
Worst miss263 MW

Average error is the mean absolute percentage gap between the forecast and reported demand. Bias is the signed mean (+16 MW per hour on average): the forecast ran high on average, an over forecast. The worst miss was 263 MW (11.0%) too high at 9 Sept 2026, 12:00 PDT (UTC-07:00): forecast 2,660 MW, reported 2,397 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, 18:00 PDT (UTC-07:00)
PACW day-ahead demand forecast and reported demand by hour Hourly reported demand and the day-ahead forecast for PACW over the last 7 days of the window, to 20 Sept 2026, 18:00 PDT (UTC-07:00). Gaps are hours with a missing, zero or implausible report. 0 750 1,500 2,250 3,000 13 Sept, 19:0014 Sept, 19:0015 Sept, 19:0016 Sept, 19:0017 Sept, 19:0018 Sept, 19:0019 Sept, 19:00
Hourly reported demand and the day-ahead forecast for PACW over the last 7 days of the window, to 20 Sept 2026, 18:00 PDT (UTC-07:00). Gaps are hours with a missing, zero or implausible report.
Data to 2026-09-20
PACW day-ahead demand forecast and reported demand by hour
Local hourReported demandDay-ahead forecast
13 Sept, 19:002,298 MW2,297 MW
13 Sept, 20:002,280 MW2,259 MW
13 Sept, 21:002,152 MW2,152 MW
13 Sept, 22:002,002 MW2,008 MW
13 Sept, 23:001,889 MW1,893 MW
14 Sept, 00:001,798 MW1,827 MW
14 Sept, 01:001,744 MW1,788 MW
14 Sept, 02:001,732 MW1,774 MW
14 Sept, 03:001,745 MW1,784 MW
14 Sept, 04:001,812 MW1,869 MW
14 Sept, 05:001,990 MW2,050 MW
14 Sept, 06:002,217 MW2,264 MW
14 Sept, 07:002,351 MW2,395 MW
14 Sept, 08:002,331 MW2,420 MW
14 Sept, 09:002,287 MW2,395 MW
14 Sept, 10:002,241 MW2,368 MW
14 Sept, 11:002,193 MW2,348 MW
14 Sept, 12:002,202 MW2,350 MW
14 Sept, 13:002,202 MW2,362 MW
14 Sept, 14:002,195 MW2,384 MW
14 Sept, 15:002,250 MW2,425 MW
14 Sept, 16:002,328 MW2,499 MW
14 Sept, 17:002,415 MW2,563 MW
14 Sept, 18:002,460 MW2,590 MW
14 Sept, 19:002,502 MW2,572 MW
14 Sept, 20:002,419 MW2,495 MW
14 Sept, 21:002,271 MW2,351 MW
14 Sept, 22:002,083 MW2,175 MW
14 Sept, 23:001,943 MW2,037 MW
15 Sept, 00:001,840 MW1,948 MW
15 Sept, 01:001,785 MW1,879 MW
15 Sept, 02:001,750 MW1,844 MW
15 Sept, 03:001,746 MW1,838 MW
15 Sept, 04:001,807 MW1,904 MW
15 Sept, 05:001,959 MW2,069 MW
15 Sept, 06:002,189 MW2,269 MW
15 Sept, 07:002,333 MW2,389 MW
15 Sept, 08:002,327 MW2,407 MW
15 Sept, 09:002,321 MW2,388 MW
15 Sept, 10:002,280 MW2,374 MW
15 Sept, 11:002,273 MW2,370 MW
15 Sept, 12:002,266 MW2,380 MW
15 Sept, 13:002,268 MW2,404 MW
15 Sept, 14:002,286 MW2,428 MW
15 Sept, 15:002,295 MW2,458 MW
15 Sept, 16:002,353 MW2,498 MW
15 Sept, 17:002,400 MW2,539 MW
15 Sept, 18:002,408 MW2,561 MW
15 Sept, 19:002,433 MW2,554 MW
15 Sept, 20:002,392 MW2,489 MW
15 Sept, 21:002,258 MW2,350 MW
15 Sept, 22:002,097 MW2,176 MW
15 Sept, 23:001,954 MW2,036 MW
16 Sept, 00:001,868 MW1,951 MW
16 Sept, 01:001,809 MW1,789 MW
16 Sept, 02:001,777 MW1,789 MW
16 Sept, 03:001,771 MW1,781 MW
16 Sept, 04:001,820 MW1,798 MW
16 Sept, 05:001,974 MW1,965 MW
16 Sept, 06:002,194 MW2,226 MW
16 Sept, 07:002,321 MW2,368 MW
16 Sept, 08:002,316 MW2,370 MW
16 Sept, 09:002,285 MW2,339 MW
16 Sept, 10:002,265 MW2,312 MW
16 Sept, 11:002,234 MW2,296 MW
16 Sept, 12:002,249 MW2,326 MW
16 Sept, 13:002,280 MW2,371 MW
16 Sept, 14:002,322 MW2,423 MW
16 Sept, 15:002,367 MW2,485 MW
16 Sept, 16:002,466 MW2,558 MW
16 Sept, 17:002,550 MW2,621 MW
16 Sept, 18:002,572 MW2,634 MW
16 Sept, 19:002,518 MW2,624 MW
16 Sept, 20:002,464 MW2,545 MW
16 Sept, 21:002,293 MW2,385 MW
16 Sept, 22:002,126 MW2,196 MW
16 Sept, 23:001,989 MW2,039 MW
17 Sept, 00:001,873 MW1,963 MW
17 Sept, 01:001,806 MW1,881 MW
17 Sept, 02:001,769 MW1,828 MW
17 Sept, 03:001,777 MW1,805 MW
17 Sept, 04:001,806 MW1,849 MW
17 Sept, 05:001,962 MW1,991 MW
17 Sept, 06:002,177 MW2,177 MW
17 Sept, 07:002,301 MW2,305 MW
17 Sept, 08:002,344 MW2,315 MW
17 Sept, 09:002,373 MW2,295 MW
17 Sept, 10:002,325 MW2,279 MW
17 Sept, 11:002,315 MW2,277 MW
17 Sept, 12:002,341 MW2,321 MW
17 Sept, 13:002,385 MW2,379 MW
17 Sept, 14:002,401 MW2,434 MW
17 Sept, 15:002,434 MW2,493 MW
17 Sept, 16:002,468 MW2,555 MW
17 Sept, 17:002,546 MW2,641 MW
17 Sept, 18:002,549 MW2,652 MW
17 Sept, 19:002,537 MW2,635 MW
17 Sept, 20:002,484 MW2,553 MW
17 Sept, 21:002,334 MW2,376 MW
17 Sept, 22:002,164 MW2,186 MW
17 Sept, 23:002,002 MW2,037 MW
18 Sept, 00:001,892 MW1,942 MW
18 Sept, 01:001,832 MW1,788 MW
18 Sept, 02:001,798 MW1,788 MW
18 Sept, 03:001,785 MW1,782 MW
18 Sept, 04:001,828 MW1,831 MW
18 Sept, 05:001,968 MW1,986 MW
18 Sept, 06:002,158 MW2,205 MW
18 Sept, 07:002,288 MW2,331 MW
18 Sept, 08:002,313 MW2,328 MW
18 Sept, 09:002,291 MW2,296 MW
18 Sept, 10:002,275 MW2,276 MW
18 Sept, 11:002,262 MW2,246 MW
18 Sept, 12:002,266 MW2,260 MW
18 Sept, 13:002,276 MW2,291 MW
18 Sept, 14:002,309 MW2,334 MW
18 Sept, 15:002,377 MW2,377 MW
18 Sept, 16:002,460 MW2,477 MW
18 Sept, 17:002,528 MW2,561 MW
18 Sept, 18:002,512 MW2,583 MW
18 Sept, 19:002,467 MW2,529 MW
18 Sept, 20:002,373 MW2,432 MW
18 Sept, 21:002,265 MW2,304 MW
18 Sept, 22:002,110 MW2,137 MW
18 Sept, 23:001,964 MW2,000 MW
19 Sept, 00:001,848 MW1,885 MW
19 Sept, 01:001,794 MW1,820 MW
19 Sept, 02:001,734 MW1,762 MW
19 Sept, 03:001,716 MW1,729 MW
19 Sept, 04:001,740 MW1,758 MW
19 Sept, 05:001,789 MW1,794 MW
19 Sept, 06:001,885 MW1,882 MW
19 Sept, 07:001,989 MW1,982 MW
19 Sept, 08:002,068 MW2,076 MW
19 Sept, 09:002,113 MW2,098 MW
19 Sept, 10:002,090 MW2,097 MW
19 Sept, 11:002,115 MW2,103 MW
19 Sept, 12:002,099 MW2,129 MW
19 Sept, 13:002,123 MW2,136 MW
19 Sept, 14:002,171 MW2,215 MW
19 Sept, 15:002,262 MW2,303 MW
19 Sept, 16:002,369 MW2,401 MW
19 Sept, 17:002,460 MW2,462 MW
19 Sept, 18:002,466 MW2,451 MW
19 Sept, 19:002,412 MW2,425 MW
19 Sept, 20:002,314 MW2,326 MW
19 Sept, 21:002,192 MW2,179 MW
19 Sept, 22:002,048 MW2,035 MW
19 Sept, 23:001,916 MW1,906 MW
20 Sept, 00:001,816 MW1,818 MW
20 Sept, 01:001,741 MW1,785 MW
20 Sept, 02:001,710 MW1,738 MW
20 Sept, 03:001,684 MW1,723 MW
20 Sept, 04:001,708 MW1,722 MW
20 Sept, 05:001,742 MW1,764 MW
20 Sept, 06:001,806 MW1,823 MW
20 Sept, 07:001,910 MW1,910 MW
20 Sept, 08:002,012 MW2,014 MW
20 Sept, 09:002,045 MW2,064 MW
20 Sept, 10:002,070 MW2,090 MW
20 Sept, 11:002,065 MW2,109 MW
20 Sept, 12:002,116 MW2,140 MW
20 Sept, 13:002,164 MW2,181 MW
20 Sept, 14:002,202 MW2,261 MW
20 Sept, 15:002,400 MW2,361 MW
20 Sept, 16:002,540 MW2,470 MW
20 Sept, 17:002,658 MW2,549 MW
20 Sept, 18:002,590 MW2,579 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.