Was the forecast right for Philadelphia on Mon Aug 31?
Philadelphia, Pennsylvania · daily high temperature in °C · forecasts from each model's archived runs, verified against the PHL observations
6 days out, 6 models put Philadelphia's Mon Aug 31 high anywhere from 31° to 34°; by the final call the field had settled to a median of 29°. The day verified at 28° against the PHL observations — cloudy.
GEM landed closest, off by 0.0°. ECMWF ran 3° hot.
What every model said, at every lead
Daily-high calls for Mon Aug 31 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 |
|---|---|---|---|---|---|---|---|---|
| 6d · 2026-08-25 | 33° | 33° | 31° | 31° | 34° | 33° | — | 31–34° |
| 5d · 2026-08-26 | 30° | 33° | 34° | 32° | 26° | 34° | 33° | 26–34° |
| 4d · 2026-08-27 | 30° | 32° | 33° | 31° | 32° | 32° | 32° | 30–33° |
| 3d · 2026-08-28 | 30° | 30° | 30° | 31° | 30° | 28° | 32° | 28–32° |
| 2d · 2026-08-29 | 30° | 30° | 30° | 26° | 30° | 28° | 31° | 26–31° |
| 1d · 2026-08-30 | 30° | 28° | 32° | 28° | 29° | 29° | 30° | 28–32° |
| 0d · 2026-08-31 | 29° | 26° | 31° | 28° | 29° | 26° | 29° | 26–31° |
| actual | 28° |
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.