Was the forecast right for Chicago on Thu Aug 6?
Chicago, Illinois · daily high temperature in °C · forecasts from each model's archived runs, verified against the ECMWF IFS analysis
11 days out, 4 models put Chicago's Thu Aug 6 high anywhere from 23° to 35°;by the final call, the day before, the field had settled to a median of 25°. The day verified at 26° against the ECMWF IFS analysis, with 3.6 mm of precipitation — drizzle.
AIFS landed closest, off by 0.6°. GEM ran 2° cool.
What every model said, at every lead
Daily-high calls for Thu Aug 6 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 |
|---|---|---|---|---|---|---|---|---|
| 11d · 2026-07-26 | 25° | 25° | 35° | — | 23° | — | — | 23–35° |
| 10d · 2026-07-27 | 30° | 25° | 30° | — | 28° | — | — | 25–30° |
| 9d · 2026-07-28 | 27° | 26° | 30° | 24° | 29° | — | — | 24–30° |
| 8d · 2026-07-29 | 24° | 28° | 27° | 27° | 31° | — | — | 24–31° |
| 7d · 2026-07-30 | 25° | 29° | 26° | 30° | 29° | — | — | 25–30° |
| 6d · 2026-07-31 | 25° | 25° | 26° | 27° | 32° | 29° | 26° | 25–32° |
| 5d · 2026-08-01 | 23° | 24° | 22° | 23° | 23° | 28° | 27° | 22–28° |
| 4d · 2026-08-02 | 24° | 24° | 26° | 22° | 22° | 25° | 23° | 22–26° |
| 3d · 2026-08-03 | 25° | 25° | 26° | 21° | 26° | 25° | 22° | 21–26° |
| 2d · 2026-08-04 | 25° | 25° | 25° | 24° | 26° | 25° | 23° | 23–26° |
| 1d · 2026-08-05 | 25° | 25° | 25° | 24° | 24° | 27° | 25° | 24–27° |
| actual | 26° |
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 ECMWF IFS analysis (temperature_2m_max). 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.