Was the forecast right for Philadelphia on Mon Sep 21?
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 Mon Sep 21 high anywhere from 71° to 79°;by the final call, the day before, the field had settled to a median of 72°. The day verified at 75° against the PHL observations — showers.
UKMO landed closest, off by 0.9°. AIGFS ran 5° cool.
What every model said, at every lead
Daily-high calls for Mon Sep 21 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 · 2026-09-06 | — | 64° | — | — | 73° | — | — | 64–73° |
| 14d · 2026-09-07 | 71° | 77° | 78° | — | 79° | — | — | 71–79° |
| 13d · 2026-09-08 | 74° | 67° | 87° | — | 79° | — | — | 67–87° |
| 12d · 2026-09-09 | 79° | 66° | 70° | — | 76° | — | — | 66–79° |
| 11d · 2026-09-10 | 70° | 65° | 71° | — | 67° | — | — | 65–71° |
| 10d · 2026-09-11 | 66° | 68° | 82° | — | 78° | — | — | 66–82° |
| 9d · 2026-09-12 | 70° | 67° | 73° | 66° | 73° | — | — | 66–73° |
| 8d · 2026-09-13 | 74° | 72° | 76° | 78° | 70° | — | — | 70–78° |
| 7d · 2026-09-14 | 72° | 71° | 89° | 74° | 74° | — | — | 71–89° |
| 6d · 2026-09-15 | 71° | 71° | 71° | 72° | 68° | 69° | 72° | 68–72° |
| 5d · 2026-09-16 | 74° | 68° | 73° | 74° | 74° | 77° | 70° | 68–77° |
| 4d · 2026-09-17 | 72° | 68° | 72° | 71° | 68° | 72° | 71° | 68–72° |
| 3d · 2026-09-18 | 72° | 68° | 72° | 72° | 70° | 72° | 73° | 68–73° |
| 2d · 2026-09-19 | 71° | 68° | 71° | 71° | 72° | 73° | 74° | 68–74° |
| 1d · 2026-09-20 | 71° | 70° | 73° | 71° | 73° | 72° | 74° | 70–74° |
| actual | 75° |
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.