Was the forecast right for Philadelphia on Fri Sep 11?
Philadelphia, Pennsylvania · daily high temperature in °F · forecasts from each model's archived runs, verified against the PHL observations
14 days out, 4 models put Philadelphia's Fri Sep 11 high anywhere from 75° to 92°; by the final call, the day before, the field had settled to a median of 83°. The day verified at 81° against the PHL observations.
AIGFS landed closest, off by 0.4°. AIFS ran 2° warm.
What every model said, at every lead
Forecast highs for Fri Sep 11 as each model's run approached it, recorded from the last archived model run per day. NBM and The Spread's own blend are omitted because they average the other models.
| Lead | AIFS | AIGFS | ECMWF | GEM | GFS | ICON | UKMO | Range |
|---|---|---|---|---|---|---|---|---|
| 15d · 2026-08-27 | — | 80° | — | — | 73° | — | — | 73–80° |
| 14d · 2026-08-28 | 89° | 76° | 92° | — | 75° | — | — | 75–92° |
| 13d · 2026-08-29 | 90° | 86° | 80° | — | 73° | — | — | 73–90° |
| 12d · 2026-08-30 | 84° | 87° | 82° | — | 81° | — | — | 81–87° |
| 11d · 2026-08-31 | 92° | 89° | 83° | — | 82° | — | — | 82–92° |
| 10d · 2026-09-01 | 84° | 84° | 77° | — | 71° | — | — | 71–84° |
| 9d · 2026-09-02 | 86° | 80° | 70° | 82° | 79° | — | — | 70–86° |
| 8d · 2026-09-03 | 78° | 83° | 77° | 82° | 78° | — | — | 77–83° |
| 7d · 2026-09-04 | 82° | 80° | 82° | 83° | 73° | — | — | 73–83° |
| 6d · 2026-09-05 | 78° | 81° | 83° | 76° | 88° | 78° | 79° | 76–88° |
| 5d · 2026-09-06 | 81° | 80° | 81° | 75° | 77° | 79° | 81° | 75–81° |
| 4d · 2026-09-07 | 83° | 80° | 82° | 76° | 81° | 77° | 79° | 76–83° |
| 3d · 2026-09-08 | 84° | 80° | 81° | 83° | 80° | 76° | 80° | 76–84° |
| 2d · 2026-09-09 | 84° | 82° | 80° | 84° | 82° | 81° | 82° | 80–84° |
| 1d · 2026-09-10 | 83° | 81° | 83° | 81° | 83° | 83° | 82° | 81–83° |
| actual | 81° |
What one day can show
A score for one day isn't very meaningful; a useful ranking needs many days of data. See which model has been most accurate in Philadelphia, or in every city The Spread scores.
Forecasts are what each model's archived runs said at the time they were recorded by The Spread; nothing is reconstructed after the fact. Truth is the PHL observations. The actual values are the ones in hand when this day was verified, usually 2 days after the date; a correction published after that is not carried into it. Archive depth varies by city; verified days exist only for dates the archive watched arrive.