Was the forecast right for Philadelphia on Thu Sep 17?
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 Thu Sep 17 high anywhere from 72° to 87°; by the final call the field had settled to a median of 85°. The day verified at 84° against the PHL observations, with 0.03 in of precipitation — showers.
ICON landed closest, off by 0.2°. GFS ran 5° hot.
What every model said, at every lead
Daily-high calls for Thu Sep 17 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 · 2026-09-02 | — | 71° | — | — | 97° | — | — | 71–97° |
| 14d · 2026-09-03 | 80° | 81° | — | — | 70° | — | — | 70–81° |
| 13d · 2026-09-04 | 80° | 72° | 76° | — | 87° | — | — | 72–87° |
| 12d · 2026-09-05 | 94° | 80° | 81° | — | 64° | — | — | 64–94° |
| 11d · 2026-09-06 | 82° | 88° | 72° | — | 69° | — | — | 69–88° |
| 10d · 2026-09-07 | 81° | 72° | 76° | — | 74° | — | — | 72–81° |
| 9d · 2026-09-08 | 85° | 80° | 77° | — | 79° | — | — | 77–85° |
| 8d · 2026-09-09 | 86° | 82° | 71° | 91° | 82° | — | — | 71–91° |
| 7d · 2026-09-10 | 85° | 85° | 82° | 86° | 86° | — | — | 82–86° |
| 6d · 2026-09-11 | 87° | 86° | 84° | 84° | 86° | 89° | — | 84–89° |
| 5d · 2026-09-12 | 85° | 81° | 82° | 86° | 86° | 86° | 85° | 81–86° |
| 4d · 2026-09-13 | 85° | 82° | 84° | 85° | 87° | 85° | 82° | 82–87° |
| 3d · 2026-09-14 | 84° | 83° | 82° | 85° | 85° | 84° | 82° | 82–85° |
| 2d · 2026-09-15 | 85° | 84° | 86° | 84° | 88° | 86° | 81° | 81–88° |
| 1d · 2026-09-16 | 84° | 85° | 87° | 84° | 88° | 83° | 83° | 83–88° |
| 0d · 2026-09-17 | 85° | 85° | 86° | 85° | 89° | 84° | 86° | 84–89° |
| actual | 84° |
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.