Was the forecast right for Chicago on Fri Sep 4?
Chicago, Illinois · daily high temperature in °C · forecasts from each model's archived runs, verified against the MDW observations
13 days out, 4 models put Chicago's Fri Sep 4 high anywhere from 25° to 28°; by the final call the field had settled to a median of 34°. The day verified at 34° against the MDW observations — thunderstorms.
GEM landed closest, off by 0.1°. AIFS ran 5° cold.
What every model said, at every lead
Daily-high calls for Fri Sep 4 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 Chicago scoreboard shows them, labelled.
| Lead | AIFS | AIGFS | ECMWF | GEM | GFS | ICON | UKMO | Range |
|---|---|---|---|---|---|---|---|---|
| 14d · 2026-08-21 | 21° | 28° | — | — | 37° | — | — | 21–37° |
| 13d · 2026-08-22 | 28° | 26° | 25° | — | 28° | — | — | 25–28° |
| 12d · 2026-08-23 | 25° | 23° | 19° | — | 26° | — | — | 19–26° |
| 11d · 2026-08-24 | 26° | 27° | 31° | — | 24° | — | — | 24–31° |
| 10d · 2026-08-25 | 28° | 36° | 24° | — | 29° | — | — | 24–36° |
| 9d · 2026-08-26 | 30° | 32° | 31° | — | 25° | — | — | 25–32° |
| 8d · 2026-08-27 | 31° | 32° | 26° | 34° | 36° | — | — | 26–36° |
| 7d · 2026-08-28 | 26° | 26° | 30° | 30° | 37° | — | — | 26–37° |
| 6d · 2026-08-29 | 26° | 27° | 34° | 26° | 34° | 35° | — | 26–35° |
| 5d · 2026-08-30 | 29° | 30° | 31° | 29° | 30° | 38° | 36° | 29–38° |
| 4d · 2026-08-31 | 30° | 28° | 31° | 25° | 36° | 32° | 27° | 25–36° |
| 3d · 2026-09-01 | 29° | 30° | 30° | 31° | 32° | 32° | 35° | 29–35° |
| 2d · 2026-09-02 | 29° | 29° | 31° | 34° | 35° | 35° | 36° | 29–36° |
| 1d · 2026-09-03 | 30° | 30° | 34° | 34° | 35° | 35° | 37° | 30–37° |
| 0d · 2026-09-04 | 29° | 33° | 33° | 34° | 35° | 34° | 36° | 29–36° |
| 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 Chicago — 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 MDW observations. Archive depth varies by city; receipts exist only for dates the archive watched arrive.