Was the forecast right for Philadelphia on Wed Sep 9?
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 Wed Sep 9 high anywhere from 81° to 96°; by the final call the field had settled to a median of 87°. The day verified at 89° against the PHL observations — cloudy.
GFS landed closest, off by 1.0°. AIGFS ran 4° cold.
What every model said, at every lead
Daily-high calls for Wed Sep 9 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 · 2026-08-25 | — | 78° | — | — | 85° | — | — | 78–85° |
| 14d · 2026-08-26 | 84° | 78° | — | — | 77° | — | — | 77–84° |
| 13d · 2026-08-27 | 85° | 81° | 96° | — | 82° | — | — | 81–96° |
| 12d · 2026-08-28 | 82° | 91° | 88° | — | 81° | — | — | 81–91° |
| 11d · 2026-08-29 | 83° | 79° | 84° | — | 98° | — | — | 79–98° |
| 10d · 2026-08-30 | 82° | 77° | 81° | — | 82° | — | — | 77–82° |
| 9d · 2026-08-31 | 81° | 81° | 88° | — | 69° | — | — | 69–88° |
| 8d · 2026-09-01 | 85° | 83° | 90° | 87° | 73° | — | — | 73–90° |
| 7d · 2026-09-02 | 87° | 90° | 86° | 85° | 96° | — | — | 85–96° |
| 6d · 2026-09-03 | 81° | 84° | 78° | 84° | 78° | 88° | — | 78–88° |
| 5d · 2026-09-04 | 83° | 82° | 81° | 84° | 84° | 86° | 87° | 81–87° |
| 4d · 2026-09-05 | 86° | 82° | 87° | 84° | 87° | 86° | 88° | 82–88° |
| 3d · 2026-09-06 | 87° | 84° | 89° | 84° | 89° | 87° | 86° | 84–89° |
| 2d · 2026-09-07 | 86° | 84° | 88° | 85° | 90° | 86° | 85° | 84–90° |
| 1d · 2026-09-08 | 87° | 84° | 87° | 87° | 88° | 87° | 87° | 84–88° |
| 0d · 2026-09-09 | 87° | 84° | 87° | 86° | 88° | 87° | 87° | 84–88° |
| actual | 89° |
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.