Was the forecast right for Philadelphia on Thu Sep 10?
Philadelphia, Pennsylvania · daily high temperature in °F · forecasts from each model's archived runs, verified against the PHL observations
14 days out, 4 models put Philadelphia's Thu Sep 10 high anywhere from 74° to 94°;by the final call, the day before, the field had settled to a median of 88°. The day verified at 90° against the PHL observations — cloudy.
GFS landed closest, off by 1.4°. ICON ran 8° cool.
What every model said, at every lead
Daily-high calls for Thu Sep 10 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, labeled.
| Lead | AIFS | AIGFS | ECMWF | GEM | GFS | ICON | UKMO | Range |
|---|---|---|---|---|---|---|---|---|
| 15d · 2026-08-26 | — | 88° | — | — | 81° | — | — | 81–88° |
| 14d · 2026-08-27 | 93° | 79° | 94° | — | 74° | — | — | 74–94° |
| 13d · 2026-08-28 | 84° | 85° | 97° | — | 89° | — | — | 84–97° |
| 12d · 2026-08-29 | 80° | 85° | 86° | — | 83° | — | — | 80–86° |
| 11d · 2026-08-30 | 87° | 79° | 81° | — | 72° | — | — | 72–87° |
| 10d · 2026-08-31 | 92° | 87° | 75° | — | 92° | — | — | 75–92° |
| 9d · 2026-09-01 | 89° | 90° | 92° | 87° | 86° | — | — | 86–92° |
| 8d · 2026-09-02 | 92° | 93° | 87° | 86° | 89° | — | — | 86–93° |
| 7d · 2026-09-03 | 84° | 89° | 83° | 92° | 92° | — | — | 83–92° |
| 6d · 2026-09-04 | 91° | 89° | 86° | 90° | 84° | 93° | 89° | 84–93° |
| 5d · 2026-09-05 | 86° | 88° | 92° | 88° | 90° | 89° | 87° | 86–92° |
| 4d · 2026-09-06 | 86° | 84° | 94° | 84° | 78° | 91° | 87° | 78–94° |
| 3d · 2026-09-07 | 87° | 85° | 92° | 88° | 80° | 78° | 85° | 78–92° |
| 2d · 2026-09-08 | 88° | 87° | 89° | 89° | 87° | 86° | 83° | 83–89° |
| 1d · 2026-09-09 | 89° | 87° | 88° | 87° | 89° | 82° | 88° | 82–89° |
| actual | 90° |
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. The actual values are the ones in hand when this day was verified, usually 2 days after the date; a correction published after that is not carried into it. Archive depth varies by city; verified days exist only for dates the archive watched arrive.