CPLW Demand Forecast Accuracy: Error, Bias and Worst Miss, 21 August to 20 September 2026
The day-ahead demand forecast for CPLW was off by 3.5% on average (mean absolute percentage error) over 719 hours from 21 August to 20 September 2026, and 72% of hours landed within 5% of the reading. Its bias was -2.6%: it ran low on average, an under forecast. The largest miss was 107 MW (17.2%) too high at 5 Sept 2026, 15:00 EDT (UTC-04:00). Dates and times are local (America/New_York).
Key Facts
- The day-ahead demand forecast for CPLW was off by 3.5% on average (mean absolute percentage error) over 719 hours from 21 August to 20 September 2026, and 72% of hours landed within 5% of the reading. Its bias was -2.6%: it ran low on average, an under forecast. The largest miss was 107 MW (17.2%) too high at 5 Sept 2026, 15:00 EDT (UTC-04:00).
- Across 53 US grids ranked by average error over their own latest 30 day windows, CPLW came 24 (1 is the smallest error).
- On average the forecast differed from reported demand by 21 MW, against average demand of 558 MW.
- The forecast was above reported demand in 21% of compared hours.
Forecast Error at a Glance
719 hours from 21 August to 20 September 2026Average error3.5%
Bias-2.6%
Hours within 5%72%
Worst miss107 MW
Average error is the mean absolute percentage gap between the forecast and reported demand. Bias is the signed mean (-17 MW per hour on average): the forecast ran low on average, an under forecast. The worst miss was 107 MW (17.2%) too high at 5 Sept 2026, 15:00 EDT (UTC-04:00): forecast 730 MW, reported 623 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)Data to 2026-09-20
| Local hour | Reported demand | Day-ahead forecast |
|---|---|---|
| 13 Sept, 22:00 | 537 MW | 532 MW |
| 13 Sept, 23:00 | 483 MW | 482 MW |
| 14 Sept, 00:00 | 436 MW | 433 MW |
| 14 Sept, 01:00 | 410 MW | 403 MW |
| 14 Sept, 02:00 | 390 MW | 385 MW |
| 14 Sept, 03:00 | 385 MW | 377 MW |
| 14 Sept, 04:00 | 386 MW | 381 MW |
| 14 Sept, 05:00 | 403 MW | 404 MW |
| 14 Sept, 06:00 | 445 MW | 437 MW |
| 14 Sept, 07:00 | 474 MW | 469 MW |
| 14 Sept, 08:00 | 495 MW | 490 MW |
| 14 Sept, 09:00 | 523 MW | 513 MW |
| 14 Sept, 10:00 | 559 MW | 541 MW |
| 14 Sept, 11:00 | 600 MW | 575 MW |
| 14 Sept, 12:00 | 637 MW | 610 MW |
| 14 Sept, 13:00 | 681 MW | 644 MW |
| 14 Sept, 14:00 | 707 MW | 674 MW |
| 14 Sept, 15:00 | 728 MW | 699 MW |
| 14 Sept, 16:00 | 746 MW | 718 MW |
| 14 Sept, 17:00 | 755 MW | 727 MW |
| 14 Sept, 18:00 | 743 MW | 720 MW |
| 14 Sept, 19:00 | 705 MW | 698 MW |
| 14 Sept, 20:00 | 677 MW | 663 MW |
| 14 Sept, 21:00 | 623 MW | 615 MW |
| 14 Sept, 22:00 | 557 MW | 559 MW |
| 14 Sept, 23:00 | 502 MW | 506 MW |
| 15 Sept, 00:00 | 455 MW | 469 MW |
| 15 Sept, 01:00 | 435 MW | 437 MW |
| 15 Sept, 02:00 | 412 MW | 417 MW |
| 15 Sept, 03:00 | 405 MW | 408 MW |
| 15 Sept, 04:00 | 412 MW | 409 MW |
| 15 Sept, 05:00 | 430 MW | 432 MW |
| 15 Sept, 06:00 | 469 MW | 468 MW |
| 15 Sept, 07:00 | 489 MW | 498 MW |
| 15 Sept, 08:00 | 506 MW | 510 MW |
| 15 Sept, 09:00 | 528 MW | 516 MW |
| 15 Sept, 10:00 | 541 MW | 524 MW |
| 15 Sept, 11:00 | 560 MW | 541 MW |
| 15 Sept, 12:00 | 581 MW | 564 MW |
| 15 Sept, 13:00 | 606 MW | 584 MW |
| 15 Sept, 14:00 | 642 MW | 600 MW |
| 15 Sept, 15:00 | 672 MW | 619 MW |
| 15 Sept, 16:00 | 696 MW | 640 MW |
| 15 Sept, 17:00 | 717 MW | 652 MW |
| 15 Sept, 18:00 | 694 MW | 648 MW |
| 15 Sept, 19:00 | 670 MW | 635 MW |
| 15 Sept, 20:00 | 657 MW | 612 MW |
| 15 Sept, 21:00 | 603 MW | 576 MW |
| 15 Sept, 22:00 | 553 MW | 528 MW |
| 15 Sept, 23:00 | 500 MW | 481 MW |
| 16 Sept, 00:00 | 458 MW | 437 MW |
| 16 Sept, 01:00 | 438 MW | 410 MW |
| 16 Sept, 02:00 | 418 MW | 393 MW |
| 16 Sept, 03:00 | 412 MW | 385 MW |
| 16 Sept, 04:00 | 416 MW | 389 MW |
| 16 Sept, 05:00 | 427 MW | 413 MW |
| 16 Sept, 06:00 | 470 MW | 448 MW |
| 16 Sept, 07:00 | 493 MW | 479 MW |
| 16 Sept, 08:00 | 508 MW | 497 MW |
| 16 Sept, 09:00 | 527 MW | 513 MW |
| 16 Sept, 10:00 | 550 MW | 535 MW |
| 16 Sept, 11:00 | 590 MW | 561 MW |
| 16 Sept, 12:00 | 641 MW | 592 MW |
| 16 Sept, 13:00 | 672 MW | 623 MW |
| 16 Sept, 14:00 | 713 MW | 656 MW |
| 16 Sept, 15:00 | 734 MW | 684 MW |
| 16 Sept, 16:00 | 752 MW | 707 MW |
| 16 Sept, 17:00 | 760 MW | 716 MW |
| 16 Sept, 18:00 | 740 MW | 710 MW |
| 16 Sept, 19:00 | 708 MW | 688 MW |
| 16 Sept, 20:00 | 687 MW | 656 MW |
| 16 Sept, 21:00 | 631 MW | 610 MW |
| 16 Sept, 22:00 | 573 MW | 555 MW |
| 16 Sept, 23:00 | 489 MW | 502 MW |
| 17 Sept, 00:00 | 482 MW | 459 MW |
| 17 Sept, 01:00 | 431 MW | 426 MW |
| 17 Sept, 02:00 | 407 MW | 407 MW |
| 17 Sept, 03:00 | 388 MW | 397 MW |
| 17 Sept, 04:00 | 400 MW | 399 MW |
| 17 Sept, 05:00 | 411 MW | 421 MW |
| 17 Sept, 06:00 | 451 MW | 455 MW |
| 17 Sept, 07:00 | 469 MW | 485 MW |
| 17 Sept, 08:00 | 503 MW | 503 MW |
| 17 Sept, 09:00 | 528 MW | 520 MW |
| 17 Sept, 10:00 | 562 MW | 546 MW |
| 17 Sept, 11:00 | 606 MW | 578 MW |
| 17 Sept, 12:00 | 652 MW | 617 MW |
| 17 Sept, 13:00 | 698 MW | 654 MW |
| 17 Sept, 14:00 | 739 MW | 692 MW |
| 17 Sept, 15:00 | 767 MW | 719 MW |
| 17 Sept, 16:00 | 771 MW | 740 MW |
| 17 Sept, 17:00 | 779 MW | 747 MW |
| 17 Sept, 18:00 | 756 MW | 739 MW |
| 17 Sept, 19:00 | 718 MW | 714 MW |
| 17 Sept, 20:00 | 694 MW | 679 MW |
| 17 Sept, 21:00 | 638 MW | 630 MW |
| 17 Sept, 22:00 | 571 MW | 574 MW |
| 17 Sept, 23:00 | 511 MW | 520 MW |
| 18 Sept, 00:00 | 464 MW | 474 MW |
| 18 Sept, 01:00 | 434 MW | 442 MW |
| 18 Sept, 02:00 | 412 MW | 420 MW |
| 18 Sept, 03:00 | 403 MW | 409 MW |
| 18 Sept, 04:00 | 411 MW | 410 MW |
| 18 Sept, 05:00 | 420 MW | 431 MW |
| 18 Sept, 06:00 | 454 MW | 463 MW |
| 18 Sept, 07:00 | 478 MW | 493 MW |
| 18 Sept, 08:00 | 502 MW | 514 MW |
| 18 Sept, 09:00 | 530 MW | 536 MW |
| 18 Sept, 10:00 | 572 MW | 566 MW |
| 18 Sept, 11:00 | 621 MW | 601 MW |
| 18 Sept, 12:00 | 668 MW | 639 MW |
| 18 Sept, 13:00 | 714 MW | 671 MW |
| 18 Sept, 14:00 | 746 MW | 700 MW |
| 18 Sept, 15:00 | 767 MW | 722 MW |
| 18 Sept, 16:00 | 786 MW | 740 MW |
| 18 Sept, 17:00 | 779 MW | 740 MW |
| 18 Sept, 18:00 | 752 MW | 724 MW |
| 18 Sept, 19:00 | 701 MW | 696 MW |
| 18 Sept, 20:00 | 668 MW | 662 MW |
| 18 Sept, 21:00 | 622 MW | 620 MW |
| 18 Sept, 22:00 | 575 MW | 572 MW |
| 18 Sept, 23:00 | 525 MW | 520 MW |
| 19 Sept, 00:00 | 484 MW | 478 MW |
| 19 Sept, 01:00 | 452 MW | 443 MW |
| 19 Sept, 02:00 | 427 MW | 420 MW |
| 19 Sept, 03:00 | 410 MW | 407 MW |
| 19 Sept, 04:00 | 411 MW | 402 MW |
| 19 Sept, 05:00 | 411 MW | 405 MW |
| 19 Sept, 06:00 | 422 MW | 417 MW |
| 19 Sept, 07:00 | 431 MW | 440 MW |
| 19 Sept, 08:00 | 461 MW | 470 MW |
| 19 Sept, 09:00 | 497 MW | 501 MW |
| 19 Sept, 10:00 | 544 MW | 532 MW |
| 19 Sept, 11:00 | 595 MW | 564 MW |
| 19 Sept, 12:00 | 637 MW | 594 MW |
| 19 Sept, 13:00 | 679 MW | 616 MW |
| 19 Sept, 14:00 | 712 MW | 632 MW |
| 19 Sept, 15:00 | 704 MW | 645 MW |
| 19 Sept, 16:00 | 669 MW | 657 MW |
| 19 Sept, 17:00 | 639 MW | 657 MW |
| 19 Sept, 18:00 | 610 MW | 644 MW |
| 19 Sept, 19:00 | 597 MW | 624 MW |
| 19 Sept, 20:00 | 575 MW | 598 MW |
| 19 Sept, 21:00 | 549 MW | 564 MW |
| 19 Sept, 22:00 | 513 MW | 524 MW |
| 19 Sept, 23:00 | 474 MW | 485 MW |
| 20 Sept, 00:00 | 441 MW | 444 MW |
| 20 Sept, 01:00 | 416 MW | 413 MW |
| 20 Sept, 02:00 | 397 MW | 394 MW |
| 20 Sept, 03:00 | 386 MW | 383 MW |
| 20 Sept, 04:00 | 380 MW | 378 MW |
| 20 Sept, 05:00 | 391 MW | 382 MW |
| 20 Sept, 06:00 | 399 MW | 393 MW |
| 20 Sept, 07:00 | 415 MW | 418 MW |
| 20 Sept, 08:00 | 446 MW | 450 MW |
| 20 Sept, 09:00 | 470 MW | 478 MW |
| 20 Sept, 10:00 | 490 MW | 500 MW |
| 20 Sept, 11:00 | 526 MW | 528 MW |
| 20 Sept, 12:00 | 577 MW | 558 MW |
| 20 Sept, 13:00 | 628 MW | 581 MW |
| 20 Sept, 14:00 | 662 MW | 599 MW |
| 20 Sept, 15:00 | 675 MW | 618 MW |
| 20 Sept, 16:00 | 675 MW | 636 MW |
| 20 Sept, 17:00 | 666 MW | 641 MW |
| 20 Sept, 18:00 | 651 MW | 636 MW |
| 20 Sept, 19:00 | 632 MW | 621 MW |
| 20 Sept, 20:00 | 620 MW | 596 MW |
| 20 Sept, 21:00 | 571 MW | 557 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.