Was the forecast right for Chicago on Wed Sep 2?
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 Wed Sep 2 high anywhere from 23° to 31°;by the final call, the day before, the field had settled to a median of 35°. The day verified at 36° against the MDW observations — drizzle.
GFS landed closest, off by 0.1°. AIFS ran 3° cool.
What every model said, at every lead
Daily-high calls for Wed Sep 2 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 |
|---|---|---|---|---|---|---|---|---|
| 13d · 2026-08-20 | 24° | 31° | 28° | — | 23° | — | — | 23–31° |
| 12d · 2026-08-21 | 26° | 21° | 30° | — | 32° | — | — | 21–32° |
| 11d · 2026-08-22 | 27° | 25° | 22° | — | 24° | — | — | 22–27° |
| 10d · 2026-08-23 | 26° | 29° | 24° | — | 22° | — | — | 22–29° |
| 9d · 2026-08-24 | 24° | 33° | 30° | 30° | 33° | — | — | 24–33° |
| 8d · 2026-08-25 | 27° | 26° | 29° | 33° | 34° | — | — | 26–34° |
| 7d · 2026-08-26 | 26° | 35° | 32° | 34° | 35° | — | — | 26–35° |
| 6d · 2026-08-27 | 27° | 27° | 31° | 34° | 35° | 31° | 34° | 27–35° |
| 5d · 2026-08-28 | 32° | 32° | 37° | 34° | 34° | 37° | 35° | 32–37° |
| 4d · 2026-08-29 | 33° | 33° | 35° | 36° | 35° | 37° | 36° | 33–37° |
| 3d · 2026-08-30 | 32° | 33° | 35° | 34° | 36° | 36° | 36° | 32–36° |
| 2d · 2026-08-31 | 33° | 33° | 33° | 34° | 35° | 35° | 36° | 33–36° |
| 1d · 2026-09-01 | 33° | 33° | 34° | 37° | 36° | 35° | 37° | 33–37° |
| actual | 36° |
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. The actual values are the ones in hand when this receipt was settled, usually 2 days after the date; a correction published after that is not carried into it. Archive depth varies by city; receipts exist only for dates the archive watched arrive.