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
13 days out, 4 models put Philadelphia's Fri Sep 11 high anywhere from 78° to 83°; by the final call the field had settled to a median of 82°. The day verified at 81° against the PHL observations — drizzle.
AIGFS landed closest, off by 0.3°. GFS ran 4° hot.
What every model said, at every lead
Daily-high calls for Fri Sep 11 as each model's runs approached it — the last archived run per day. NBM and The Spread's own blend are consensus products and stay out of these ranges and rankings; the Philadelphia scoreboard shows them, labelled.
| Lead | AIFS | AIGFS | ECMWF | GEM | GFS | ICON | UKMO | Range |
|---|---|---|---|---|---|---|---|---|
| 15d · 2026-08-27 | — | 83° | — | — | 76° | — | — | 76–83° |
| 14d · 2026-08-28 | 84° | 80° | — | — | 72° | — | — | 72–84° |
| 13d · 2026-08-29 | 81° | 78° | 83° | — | 79° | — | — | 78–83° |
| 12d · 2026-08-30 | 81° | 84° | 68° | — | 72° | — | — | 68–84° |
| 11d · 2026-08-31 | 90° | 78° | 84° | — | 83° | — | — | 78–90° |
| 10d · 2026-09-01 | 91° | 77° | 95° | — | 83° | — | — | 77–95° |
| 9d · 2026-09-02 | 86° | 85° | 83° | — | 78° | — | — | 78–86° |
| 8d · 2026-09-03 | 78° | 82° | 77° | 92° | 75° | — | — | 75–92° |
| 7d · 2026-09-04 | 78° | 83° | 77° | 82° | 78° | — | — | 77–83° |
| 6d · 2026-09-05 | 84° | 72° | 79° | 80° | 76° | 81° | — | 72–84° |
| 5d · 2026-09-06 | 81° | 80° | 79° | 74° | 81° | 75° | 79° | 74–81° |
| 4d · 2026-09-07 | 80° | 80° | 83° | 78° | 81° | 78° | 82° | 78–83° |
| 3d · 2026-09-08 | 83° | 79° | 79° | 81° | 81° | 74° | 81° | 74–83° |
| 2d · 2026-09-09 | 83° | 80° | 82° | 82° | 80° | 79° | 81° | 79–83° |
| 1d · 2026-09-10 | 84° | 82° | 79° | 81° | 87° | 81° | 84° | 79–87° |
| 0d · 2026-09-11 | 81° | 81° | 83° | 82° | 85° | 83° | 82° | 81–85° |
| actual | 81° |
Read it honestly
This is one date, not a league table. A model can win a day it deserved to lose; rankings only mean something over a window. For that, see which model has been most accurate in Philadelphia — or every city The Spread scores.
Forecasts are what each model's archived runs said at the time, captured at The Spread's sweep times — never reconstructed after the fact. Truth is the PHL observations. Archive depth varies by city; receipts exist only for dates the archive watched arrive.