Was the forecast right for Philadelphia on Tue Sep 1?
Philadelphia, Pennsylvania · daily high temperature in °C · forecasts from each model's archived runs, verified against the PHL observations
7 days out, 5 models put Philadelphia's Tue Sep 1 high anywhere from 26° to 36°; by the final call the field had settled to a median of 32°. The day verified at 34° against the PHL observations, with 21.1 mm of precipitation — thunderstorms.
GFS landed closest, off by 0.1°. GEM ran 3° cold.
What every model said, at every lead
Daily-high calls for Tue Sep 1 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 |
|---|---|---|---|---|---|---|---|---|
| 7d · 2026-08-25 | 34° | 31° | 36° | 33° | 26° | — | — | 26–36° |
| 6d · 2026-08-26 | 34° | 34° | 36° | 33° | 36° | 34° | — | 33–36° |
| 5d · 2026-08-27 | 32° | 34° | 36° | 32° | 34° | 32° | 32° | 32–36° |
| 4d · 2026-08-28 | 30° | 32° | 32° | 33° | 28° | 33° | 29° | 28–33° |
| 3d · 2026-08-29 | 32° | 32° | 35° | 33° | 33° | 33° | 34° | 32–35° |
| 2d · 2026-08-30 | 32° | 32° | 35° | 34° | 32° | 34° | 34° | 32–35° |
| 1d · 2026-08-31 | 31° | 32° | 34° | 30° | 33° | 32° | 33° | 30–34° |
| 0d · 2026-09-01 | 32° | 32° | 31° | 31° | 34° | 33° | 33° | 31–34° |
| actual | 34° |
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.