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

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

The day-ahead demand forecast for NEVP was off by 7.8% on average (mean absolute percentage error) over 717 hours from 21 August to 20 September 2026, and 38% of hours landed within 5% of the reading. Its bias was -7.5%: it ran low on average, an under forecast. The largest miss was 1,609 MW (19.7%) too low at 9 Sept 2026, 17:00 PDT (UTC-07:00). Dates and times are local (America/Los_Angeles).

Key Facts

  • The day-ahead demand forecast for NEVP was off by 7.8% on average (mean absolute percentage error) over 717 hours from 21 August to 20 September 2026, and 38% of hours landed within 5% of the reading. Its bias was -7.5%: it ran low on average, an under forecast. The largest miss was 1,609 MW (19.7%) too low at 9 Sept 2026, 17:00 PDT (UTC-07:00).
  • Across 53 US grids ranked by average error over their own latest 30 day windows, NEVP came 39 (1 is the smallest error).
  • On average the forecast differed from reported demand by 484 MW, against average demand of 6,107 MW.
  • The forecast was above reported demand in 7% of compared hours.

Forecast Error at a Glance

717 hours from 21 August to 20 September 2026
Average error7.8%
Bias-7.5%
Hours within 5%38%
Worst miss1,609 MW

Average error is the mean absolute percentage gap between the forecast and reported demand. Bias is the signed mean (-471 MW per hour on average): the forecast ran low on average, an under forecast. The worst miss was 1,609 MW (19.7%) too low at 9 Sept 2026, 17:00 PDT (UTC-07:00): forecast 6,555 MW, reported 8,164 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)
NEVP day-ahead demand forecast and reported demand by hour Hourly reported demand and the day-ahead forecast for NEVP 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 2,000 4,000 6,000 8,000 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 NEVP 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
NEVP day-ahead demand forecast and reported demand by hour
Local hourReported demandDay-ahead forecast
13 Sept, 19:006,840 MW6,672 MW
13 Sept, 20:006,555 MW6,405 MW
13 Sept, 21:006,211 MW6,125 MW
13 Sept, 22:005,855 MW5,833 MW
13 Sept, 23:005,488 MW5,450 MW
14 Sept, 00:005,181 MW5,162 MW
14 Sept, 01:004,946 MW4,983 MW
14 Sept, 02:004,739 MW4,788 MW
14 Sept, 03:004,598 MW4,647 MW
14 Sept, 04:004,555 MW4,525 MW
14 Sept, 05:004,626 MW4,452 MW
14 Sept, 06:004,687 MW4,455 MW
14 Sept, 07:005,015 MW4,588 MW
14 Sept, 08:005,973 MW4,805 MW
14 Sept, 09:006,140 MW5,097 MW
14 Sept, 10:006,117 MW5,390 MW
14 Sept, 11:006,160 MW5,691 MW
14 Sept, 12:006,203 MW6,025 MW
14 Sept, 13:006,376 MW6,336 MW
14 Sept, 14:006,699 MW6,628 MW
14 Sept, 15:006,835 MW7,025 MW
14 Sept, 16:007,113 MW7,160 MW
14 Sept, 17:007,153 MW7,148 MW
14 Sept, 18:006,946 MW6,904 MW
14 Sept, 19:006,675 MW6,702 MW
14 Sept, 20:006,351 MW6,393 MW
14 Sept, 21:006,102 MW6,109 MW
14 Sept, 22:005,580 MW5,762 MW
14 Sept, 23:005,176 MW5,361 MW
15 Sept, 00:004,893 MW4,876 MW
15 Sept, 01:004,632 MW4,613 MW
15 Sept, 02:004,435 MW4,447 MW
15 Sept, 03:004,309 MW4,360 MW
15 Sept, 04:004,270 MW4,275 MW
15 Sept, 05:004,345 MW4,345 MW
15 Sept, 06:004,439 MW4,401 MW
15 Sept, 07:004,831 MW4,478 MW
15 Sept, 08:005,746 MW4,641 MW
15 Sept, 09:006,042 MW4,881 MW
15 Sept, 10:006,176 MW5,063 MW
15 Sept, 11:006,162 MW5,402 MW
15 Sept, 12:006,165 MW5,734 MW
15 Sept, 13:006,227 MW6,055 MW
15 Sept, 14:006,942 MW6,407 MW
15 Sept, 15:006,877 MW6,788 MW
15 Sept, 16:007,193 MW6,951 MW
15 Sept, 17:007,187 MW7,021 MW
15 Sept, 18:007,270 MW6,799 MW
15 Sept, 19:006,925 MW6,652 MW
15 Sept, 20:006,699 MW6,359 MW
15 Sept, 21:006,430 MW6,027 MW
15 Sept, 22:006,019 MW5,623 MW
15 Sept, 23:005,654 MW5,222 MW
16 Sept, 00:005,365 MW4,932 MW
16 Sept, 01:005,085 MW4,801 MW
16 Sept, 02:004,851 MW4,595 MW
16 Sept, 03:004,659 MW4,455 MW
16 Sept, 04:004,598 MW4,371 MW
16 Sept, 05:004,661 MW4,311 MW
16 Sept, 06:004,738 MW4,318 MW
16 Sept, 07:005,091 MW4,366 MW
16 Sept, 08:006,036 MW4,576 MW
16 Sept, 09:006,245 MW4,819 MW
16 Sept, 10:006,348 MW5,022 MW
16 Sept, 11:006,385 MW5,305 MW
16 Sept, 12:006,300 MW5,648 MW
16 Sept, 13:006,262 MW5,892 MW
16 Sept, 14:006,575 MW6,162 MW
16 Sept, 15:006,773 MW6,522 MW
16 Sept, 16:007,021 MW6,708 MW
16 Sept, 17:007,078 MW6,707 MW
16 Sept, 18:006,924 MW6,431 MW
16 Sept, 19:006,783 MW6,306 MW
16 Sept, 20:006,556 MW6,019 MW
16 Sept, 21:006,281 MW5,705 MW
16 Sept, 22:005,925 MW5,373 MW
16 Sept, 23:005,555 MW4,972 MW
17 Sept, 00:005,264 MW4,819 MW
17 Sept, 01:005,000 MW4,572 MW
17 Sept, 02:004,814 MW4,421 MW
17 Sept, 03:004,669 MW4,292 MW
17 Sept, 04:004,623 MW4,337 MW
17 Sept, 05:004,701 MW4,407 MW
17 Sept, 06:004,800 MW4,458 MW
17 Sept, 07:004,889 MW4,421 MW
17 Sept, 08:005,703 MW4,588 MW
17 Sept, 09:006,006 MW4,796 MW
17 Sept, 10:006,110 MW5,024 MW
17 Sept, 11:006,199 MW5,198 MW
17 Sept, 12:006,238 MW5,480 MW
17 Sept, 13:006,199 MW5,822 MW
17 Sept, 14:006,565 MW6,087 MW
17 Sept, 15:006,519 MW6,330 MW
17 Sept, 16:006,686 MW6,541 MW
17 Sept, 17:006,733 MW6,563 MW
17 Sept, 18:006,594 MW6,441 MW
17 Sept, 19:006,495 MW6,326 MW
17 Sept, 20:006,329 MW6,066 MW
17 Sept, 21:006,043 MW5,834 MW
17 Sept, 22:00n/a5,452 MW
17 Sept, 23:00n/a5,088 MW
18 Sept, 00:005,088 MW4,649 MW
18 Sept, 01:004,871 MW4,408 MW
18 Sept, 02:004,704 MW4,226 MW
18 Sept, 03:004,570 MW4,099 MW
18 Sept, 04:004,502 MW3,989 MW
18 Sept, 05:004,545 MW4,050 MW
18 Sept, 06:004,616 MW4,073 MW
18 Sept, 07:004,879 MW4,289 MW
18 Sept, 08:005,394 MW4,477 MW
18 Sept, 09:005,585 MW4,719 MW
18 Sept, 10:005,853 MW4,854 MW
18 Sept, 11:005,986 MW5,098 MW
18 Sept, 12:006,197 MW5,322 MW
18 Sept, 13:006,399 MW5,569 MW
18 Sept, 14:006,650 MW5,829 MW
18 Sept, 15:006,734 MW6,209 MW
18 Sept, 16:006,608 MW6,315 MW
18 Sept, 17:006,588 MW6,425 MW
18 Sept, 18:006,341 MW6,128 MW
18 Sept, 19:006,104 MW5,928 MW
18 Sept, 20:005,821 MW5,666 MW
18 Sept, 21:005,505 MW5,380 MW
18 Sept, 22:005,154 MW5,134 MW
18 Sept, 23:004,847 MW4,834 MW
19 Sept, 00:004,614 MW4,528 MW
19 Sept, 01:004,392 MW4,336 MW
19 Sept, 02:004,201 MW4,170 MW
19 Sept, 03:004,050 MW4,032 MW
19 Sept, 04:003,975 MW3,945 MW
19 Sept, 05:003,966 MW3,932 MW
19 Sept, 06:003,958 MW3,899 MW
19 Sept, 07:004,008 MW3,959 MW
19 Sept, 08:004,996 MW4,096 MW
19 Sept, 09:005,240 MW4,253 MW
19 Sept, 10:005,365 MW4,403 MW
19 Sept, 11:005,514 MW4,626 MW
19 Sept, 12:005,536 MW4,814 MW
19 Sept, 13:005,528 MW5,108 MW
19 Sept, 14:005,914 MW5,424 MW
19 Sept, 15:006,027 MW5,808 MW
19 Sept, 16:006,387 MW6,059 MW
19 Sept, 17:006,445 MW6,221 MW
19 Sept, 18:006,216 MW6,002 MW
19 Sept, 19:005,937 MW5,790 MW
19 Sept, 20:005,606 MW5,522 MW
19 Sept, 21:005,313 MW5,268 MW
19 Sept, 22:004,992 MW5,049 MW
19 Sept, 23:004,674 MW4,768 MW
20 Sept, 00:004,414 MW4,492 MW
20 Sept, 01:004,193 MW4,312 MW
20 Sept, 02:004,011 MW4,158 MW
20 Sept, 03:003,880 MW4,040 MW
20 Sept, 04:003,804 MW3,958 MW
20 Sept, 05:003,788 MW3,901 MW
20 Sept, 06:003,773 MW3,898 MW
20 Sept, 07:003,768 MW3,818 MW
20 Sept, 08:003,919 MW3,989 MW
20 Sept, 09:004,090 MW4,123 MW
20 Sept, 10:004,356 MW4,271 MW
20 Sept, 11:004,605 MW4,553 MW
20 Sept, 12:004,917 MW4,809 MW
20 Sept, 13:005,334 MW5,103 MW
20 Sept, 14:005,679 MW5,379 MW
20 Sept, 15:006,011 MW5,730 MW
20 Sept, 16:006,297 MW6,026 MW
20 Sept, 17:006,390 MW6,151 MW
20 Sept, 18:005,961 MW5,961 MW

Assumptions

  • Only hours with both a forecast and a positive demand reading count (717 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.