Was the forecast right for Philadelphia on Sun Sep 6?
Philadelphia, Pennsylvania · daily high temperature in °C · 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 26° to 34°; by the final call the field had settled to a median of 27°. The day verified at 28° against the PHL observations — drizzle.
AIFS landed closest, off by 0.7°. AIGFS ran 2° 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 | 34° | 26° | 29° | — | 27° | — | — | 26–34° |
| 11d · 2026-08-26 | 31° | 32° | 30° | — | 22° | — | — | 22–32° |
| 10d · 2026-08-27 | 27° | 34° | 26° | — | 24° | — | — | 24–34° |
| 9d · 2026-08-28 | 27° | 26° | 30° | — | 29° | — | — | 26–30° |
| 8d · 2026-08-29 | 25° | 27° | 25° | 28° | 32° | — | — | 25–32° |
| 7d · 2026-08-30 | 25° | 26° | 25° | 23° | 28° | — | — | 23–28° |
| 6d · 2026-08-31 | 25° | 25° | 24° | 23° | 25° | 24° | — | 23–25° |
| 5d · 2026-09-01 | 26° | 26° | 29° | 26° | 28° | 25° | 27° | 25–29° |
| 4d · 2026-09-02 | 26° | 25° | 25° | 26° | 27° | 27° | 26° | 25–27° |
| 3d · 2026-09-03 | 26° | 26° | 25° | 26° | 24° | 26° | 26° | 24–26° |
| 2d · 2026-09-04 | 26° | 25° | 25° | 28° | 26° | 26° | 26° | 25–28° |
| 1d · 2026-09-05 | 27° | 26° | 26° | 27° | 26° | 25° | 27° | 25–27° |
| 0d · 2026-09-06 | 28° | 27° | 27° | 27° | 27° | 27° | 27° | 27–28° |
| actual | 28° |
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.