Was the forecast right for Chicago on Sun Aug 30?
Chicago, Illinois · daily high temperature in °C · forecasts from each model's archived runs, verified against the MDW observations
10 days out, 4 models put Chicago's Sun Aug 30 high anywhere from 19° to 31°;by the final call, the day before, the field had settled to a median of 28°. The day verified at 27° against the MDW observations, with 4.1 mm of precipitation — thunderstorms.
AIFS landed closest, off by 0.1°. UKMO ran 4° warm.
What every model said, at every lead
Daily-high calls for Sun Aug 30 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 |
|---|---|---|---|---|---|---|---|---|
| 10d · 2026-08-20 | 19° | 28° | 28° | — | 31° | — | — | 19–31° |
| 9d · 2026-08-21 | 27° | 29° | 28° | 29° | 29° | — | — | 27–29° |
| 8d · 2026-08-22 | 27° | 24° | 25° | 26° | 27° | — | — | 24–27° |
| 7d · 2026-08-23 | 26° | 22° | 29° | 28° | 26° | — | — | 22–29° |
| 6d · 2026-08-24 | 29° | 31° | 29° | 29° | 32° | 34° | 26° | 26–34° |
| 5d · 2026-08-25 | 30° | 31° | 31° | 30° | 32° | 31° | 33° | 30–33° |
| 4d · 2026-08-26 | 30° | 30° | 31° | 32° | 30° | 33° | 32° | 30–33° |
| 3d · 2026-08-27 | 28° | 30° | 32° | 31° | 31° | 33° | 32° | 28–33° |
| 2d · 2026-08-28 | 27° | 28° | 31° | 29° | 31° | 32° | 32° | 27–32° |
| 1d · 2026-08-29 | 27° | 27° | 28° | 29° | 28° | 30° | 32° | 27–32° |
| actual | 27° |
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.