Was the forecast right for Chicago on Thu Sep 17?
Chicago, Illinois · daily high temperature in °F · forecasts from each model's archived runs, verified against the MDW observations
13 days out, 4 models put Chicago's Thu Sep 17 high anywhere from 68° to 90°; by the final call the field had settled to a median of 76°. The day verified at 82° against the MDW observations, with 1.79 in of precipitation — thunderstorms.
GFS landed closest, off by 1.4°. AIGFS ran 8° cold.
What every model said, at every lead
Daily-high calls for Thu Sep 17 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 · 2026-09-02 | — | 72° | — | — | 79° | — | — | 72–79° |
| 14d · 2026-09-03 | 70° | 78° | — | — | 70° | — | — | 70–78° |
| 13d · 2026-09-04 | 68° | 87° | 90° | — | 83° | — | — | 68–90° |
| 12d · 2026-09-05 | 76° | 66° | 78° | — | 68° | — | — | 66–78° |
| 11d · 2026-09-06 | 81° | 78° | 73° | — | 73° | — | — | 73–81° |
| 10d · 2026-09-07 | 69° | 69° | 67° | — | 72° | — | — | 67–72° |
| 9d · 2026-09-08 | 84° | 91° | 69° | — | 91° | — | — | 69–91° |
| 8d · 2026-09-09 | 78° | 90° | 83° | 90° | 69° | — | — | 69–90° |
| 7d · 2026-09-10 | 78° | 66° | 69° | 69° | 67° | — | — | 66–78° |
| 6d · 2026-09-11 | 74° | 71° | 71° | 71° | 91° | 71° | — | 71–91° |
| 5d · 2026-09-12 | 72° | 72° | 81° | 74° | 68° | 74° | 89° | 68–89° |
| 4d · 2026-09-13 | 71° | 69° | 75° | 72° | 74° | 73° | 70° | 69–75° |
| 3d · 2026-09-14 | 73° | 76° | 82° | 75° | 70° | 74° | 74° | 70–82° |
| 2d · 2026-09-15 | 74° | 74° | 78° | 74° | 80° | 76° | 70° | 70–80° |
| 1d · 2026-09-16 | 75° | 75° | 77° | 79° | 78° | 75° | 74° | 74–79° |
| 0d · 2026-09-17 | 76° | 74° | 84° | 76° | 81° | 78° | 75° | 74–84° |
| actual | 82° |
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. Archive depth varies by city; receipts exist only for dates the archive watched arrive.