Was the forecast right for Chicago on Thu Sep 3?
Chicago, Illinois · daily high temperature in °F · forecasts from each model's archived runs, verified against the MDW observations
14 days out, 4 models put Chicago's Thu Sep 3 high anywhere from 78° to 95°;by the final call, the day before, the field had settled to a median of 93°. The day verified at 92° against the MDW observations — thunderstorms.
ICON landed closest, off by 1.0°. GEM ran 7° warm.
What every model said, at every lead
Daily-high calls for Thu Sep 3 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 · 2026-08-20 | 78° | 95° | 84° | — | 90° | — | — | 78–95° |
| 13d · 2026-08-21 | 75° | 73° | 78° | — | 89° | — | — | 73–89° |
| 12d · 2026-08-22 | 78° | 74° | 75° | — | 75° | — | — | 74–78° |
| 11d · 2026-08-23 | 83° | 88° | 70° | — | 77° | — | — | 70–88° |
| 10d · 2026-08-24 | 80° | 86° | 91° | — | 93° | — | — | 80–93° |
| 9d · 2026-08-25 | 86° | 97° | 84° | 91° | 88° | — | — | 84–97° |
| 8d · 2026-08-26 | 84° | 85° | 85° | 84° | 96° | — | — | 84–96° |
| 7d · 2026-08-27 | 84° | 83° | 83° | 81° | 99° | — | — | 81–99° |
| 6d · 2026-08-28 | 80° | 83° | 84° | 78° | 93° | 94° | 87° | 78–94° |
| 5d · 2026-08-29 | 87° | 86° | 91° | 88° | 88° | 85° | 87° | 85–91° |
| 4d · 2026-08-30 | 84° | 86° | 87° | 84° | 93° | 97° | 96° | 84–97° |
| 3d · 2026-08-31 | 86° | 91° | 89° | 89° | 96° | 93° | 86° | 86–96° |
| 2d · 2026-09-01 | 86° | 90° | 93° | 91° | 92° | 93° | 93° | 86–93° |
| 1d · 2026-09-02 | 86° | 90° | 86° | 99° | 97° | 93° | 93° | 86–99° |
| actual | 92° |
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.