Was the forecast right for Chicago on Sun Sep 20?
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 Sun Sep 20 high anywhere from 65° to 78°; by the final call the field had settled to a median of 69°. The day verified at 69° against the MDW observations, with 1.5 in of precipitation — thunderstorms.
ECMWF landed closest, off by 0.0°. UKMO ran 2° warm.
What every model said, at every lead
Daily-high calls for Sun Sep 20 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 · 2026-09-05 | — | 63° | — | — | 72° | — | — | 63–72° |
| 14d · 2026-09-06 | 71° | 56° | — | — | 79° | — | — | 56–79° |
| 13d · 2026-09-07 | 75° | 67° | 78° | — | 65° | — | — | 65–78° |
| 12d · 2026-09-08 | 66° | 70° | 68° | — | 71° | — | — | 66–71° |
| 11d · 2026-09-09 | 64° | 74° | 79° | — | 79° | — | — | 64–79° |
| 10d · 2026-09-10 | 67° | 78° | 72° | — | 79° | — | — | 67–79° |
| 9d · 2026-09-11 | 64° | 68° | 67° | — | 72° | — | — | 64–72° |
| 8d · 2026-09-12 | 67° | 66° | 67° | 67° | 62° | — | — | 62–67° |
| 7d · 2026-09-13 | 69° | 65° | 85° | 68° | 74° | — | — | 65–85° |
| 6d · 2026-09-14 | 69° | 72° | 86° | 86° | 76° | 74° | — | 69–86° |
| 5d · 2026-09-15 | 69° | 65° | 74° | 70° | 70° | 71° | 67° | 65–74° |
| 4d · 2026-09-16 | 71° | 69° | 70° | 70° | 71° | 73° | 68° | 68–73° |
| 3d · 2026-09-17 | 70° | 69° | 70° | 69° | 69° | 72° | 68° | 68–72° |
| 2d · 2026-09-18 | 70° | 69° | 70° | 70° | 67° | 72° | 72° | 67–72° |
| 1d · 2026-09-19 | 70° | 68° | 72° | 69° | 70° | 72° | 79° | 68–79° |
| 0d · 2026-09-20 | 68° | 67° | 69° | 69° | 68° | 69° | 71° | 67–71° |
| actual | 69° |
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.