Was the forecast right for Philadelphia on Tue Sep 15?
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 Tue Sep 15 high anywhere from 74° to 97°; by the final call the field had settled to a median of 77°. The day verified at 79° against the PHL observations — cloudy.
GFS landed closest, off by 0.2°. AIFS ran 3° cold.
What every model said, at every lead
Daily-high calls for Tue Sep 15 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 · 2026-08-31 | — | 84° | — | — | 84° | — | — | 84–84° |
| 14d · 2026-09-01 | 81° | 71° | — | — | 62° | — | — | 62–81° |
| 13d · 2026-09-02 | 97° | 74° | 93° | — | 96° | — | — | 74–97° |
| 12d · 2026-09-03 | 85° | 88° | 77° | — | 84° | — | — | 77–88° |
| 11d · 2026-09-04 | 82° | 82° | 93° | — | 90° | — | — | 82–93° |
| 10d · 2026-09-05 | 79° | 87° | 74° | — | 98° | — | — | 74–98° |
| 9d · 2026-09-06 | 75° | 85° | 97° | — | 88° | — | — | 75–97° |
| 8d · 2026-09-07 | 80° | 89° | 82° | 71° | 85° | — | — | 71–89° |
| 7d · 2026-09-08 | 78° | 74° | 85° | 69° | 93° | — | — | 69–93° |
| 6d · 2026-09-09 | 76° | 78° | 85° | 80° | 90° | 90° | — | 76–90° |
| 5d · 2026-09-10 | 76° | 79° | 75° | 74° | 82° | 76° | 79° | 74–82° |
| 4d · 2026-09-11 | 76° | 77° | 76° | 78° | 77° | 74° | 80° | 74–80° |
| 3d · 2026-09-12 | 76° | 76° | 76° | 76° | 80° | 74° | 78° | 74–80° |
| 2d · 2026-09-13 | 77° | 77° | 76° | 77° | 79° | 76° | 78° | 76–79° |
| 1d · 2026-09-14 | 76° | 77° | 75° | 78° | 79° | 77° | 77° | 75–79° |
| 0d · 2026-09-15 | 76° | 77° | 76° | 78° | 79° | 77° | 77° | 76–79° |
| actual | 79° |
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.