Was the forecast right for Philadelphia on Sun Sep 6?
Philadelphia, Pennsylvania · daily high temperature in °F · forecasts from each model's archived runs, verified against the PHL observations
12 days out, 4 models put Philadelphia's Sun Sep 6 high anywhere from 78° to 93°; by the final call the field had settled to a median of 81°. The day verified at 83° against the PHL observations — drizzle.
AIFS landed closest, off by 1.3°. AIGFS ran 3° cold.
What every model said, at every lead
Daily-high calls for Sun Sep 6 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 |
|---|---|---|---|---|---|---|---|---|
| 12d · 2026-08-25 | 93° | 78° | 85° | — | 81° | — | — | 78–93° |
| 11d · 2026-08-26 | 87° | 90° | 87° | — | 71° | — | — | 71–90° |
| 10d · 2026-08-27 | 81° | 94° | 78° | — | 74° | — | — | 74–94° |
| 9d · 2026-08-28 | 81° | 79° | 85° | — | 84° | — | — | 79–85° |
| 8d · 2026-08-29 | 77° | 81° | 78° | 82° | 89° | — | — | 77–89° |
| 7d · 2026-08-30 | 77° | 79° | 76° | 74° | 82° | — | — | 74–82° |
| 6d · 2026-08-31 | 78° | 76° | 75° | 74° | 77° | 75° | — | 74–78° |
| 5d · 2026-09-01 | 79° | 79° | 84° | 79° | 82° | 78° | 81° | 78–84° |
| 4d · 2026-09-02 | 78° | 77° | 76° | 80° | 81° | 80° | 80° | 76–81° |
| 3d · 2026-09-03 | 79° | 78° | 77° | 79° | 76° | 79° | 79° | 76–79° |
| 2d · 2026-09-04 | 78° | 78° | 77° | 83° | 79° | 80° | 80° | 77–83° |
| 1d · 2026-09-05 | 80° | 79° | 79° | 81° | 78° | 77° | 81° | 77–81° |
| 0d · 2026-09-06 | 82° | 80° | 81° | 81° | 81° | 80° | 80° | 80–82° |
| actual | 83° |
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.