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
14 days out, 4 models put Chicago's Fri Sep 4 high anywhere from 21° to 24°;by the final call, the day before, the field had settled to a median of 34°. The day verified at 34° against the MDW observations — thunderstorms.
GEM landed closest, off by 0.2°. AIFS ran 3° cool.
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 |
|---|---|---|---|---|---|---|---|---|
| 15d · 2026-08-20 | — | 34° | — | — | 28° | — | — | 28–34° |
| 14d · 2026-08-21 | 24° | 23° | 21° | — | 24° | — | — | 21–24° |
| 13d · 2026-08-22 | 26° | 25° | 25° | — | 26° | — | — | 25–26° |
| 12d · 2026-08-23 | 31° | 26° | 24° | — | 26° | — | — | 24–31° |
| 11d · 2026-08-24 | 25° | 27° | 25° | — | 33° | — | — | 25–33° |
| 10d · 2026-08-25 | 31° | 29° | 30° | — | 35° | — | — | 29–35° |
| 9d · 2026-08-26 | 31° | 32° | 29° | 33° | 32° | — | — | 29–33° |
| 8d · 2026-08-27 | 26° | 32° | 25° | 33° | 38° | — | — | 25–38° |
| 7d · 2026-08-28 | 25° | 26° | 30° | 26° | 32° | — | — | 25–32° |
| 6d · 2026-08-29 | 28° | 24° | 35° | 27° | 33° | 36° | 36° | 24–36° |
| 5d · 2026-08-30 | 28° | 29° | 32° | 26° | 35° | 37° | 36° | 26–37° |
| 4d · 2026-08-31 | 28° | 29° | 30° | 29° | 36° | 35° | 33° | 28–36° |
| 3d · 2026-09-01 | 28° | 29° | 31° | 32° | 36° | 34° | 34° | 28–36° |
| 2d · 2026-09-02 | 31° | 31° | 32° | 33° | 36° | 36° | 36° | 31–36° |
| 1d · 2026-09-03 | 31° | 32° | 32° | 34° | 35° | 35° | 36° | 31–36° |
| 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. 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.