Was the forecast right for Philadelphia on Sun Sep 13?
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 Sun Sep 13 high anywhere from 76° to 92°; by the final call the field had settled to a median of 83°. The day verified at 85° against the PHL observations, with 1.47 in of precipitation — thunderstorms.
UKMO landed closest, off by 0.9°. GEM ran 4° cold.
What every model said, at every lead
Daily-high calls for Sun Sep 13 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 · 2026-08-29 | — | 83° | — | — | 78° | — | — | 78–83° |
| 14d · 2026-08-30 | 80° | 74° | — | — | 71° | — | — | 71–80° |
| 13d · 2026-08-31 | 92° | 79° | 76° | — | 78° | — | — | 76–92° |
| 12d · 2026-09-01 | 92° | 84° | 96° | — | 89° | — | — | 84–96° |
| 11d · 2026-09-02 | 89° | 91° | 78° | — | 87° | — | — | 78–91° |
| 10d · 2026-09-03 | 77° | 83° | 66° | — | 84° | — | — | 66–84° |
| 9d · 2026-09-04 | 77° | 88° | 79° | — | 78° | — | — | 77–88° |
| 8d · 2026-09-05 | 87° | 81° | 85° | 88° | 84° | — | — | 81–88° |
| 7d · 2026-09-06 | 89° | 87° | 86° | 84° | 89° | — | — | 84–89° |
| 6d · 2026-09-07 | 83° | 86° | 82° | 86° | 77° | 86° | — | 77–86° |
| 5d · 2026-09-08 | 82° | 83° | 85° | 75° | 80° | 86° | 83° | 75–86° |
| 4d · 2026-09-09 | 84° | 77° | 83° | 80° | 82° | 82° | 84° | 77–84° |
| 3d · 2026-09-10 | 84° | 80° | 82° | 81° | 87° | 82° | 84° | 80–87° |
| 2d · 2026-09-11 | 85° | 82° | 80° | 78° | 83° | 83° | 86° | 78–86° |
| 1d · 2026-09-12 | 83° | 81° | 85° | 83° | 84° | 80° | 86° | 80–86° |
| 0d · 2026-09-13 | 82° | 82° | 84° | 81° | 86° | 83° | 84° | 81–86° |
| actual | 85° |
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.