Was the forecast right for Chicago on Fri Sep 18?
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 Fri Sep 18 high anywhere from 66° to 78°; by the final call the field had settled to a median of 72°. The day verified at 72° against the MDW observations — thunderstorms.
ECMWF landed closest, off by 0.4°. GFS ran 2° hot.
What every model said, at every lead
Daily-high calls for Fri Sep 18 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 · 2026-09-03 | — | 81° | — | — | 72° | — | — | 72–81° |
| 14d · 2026-09-04 | 73° | 73° | — | — | 68° | — | — | 68–73° |
| 13d · 2026-09-05 | 70° | 66° | 71° | — | 78° | — | — | 66–78° |
| 12d · 2026-09-06 | 67° | 64° | 73° | — | 74° | — | — | 64–74° |
| 11d · 2026-09-07 | 68° | 76° | 71° | — | 65° | — | — | 65–76° |
| 10d · 2026-09-08 | 78° | 70° | 62° | — | 64° | — | — | 62–78° |
| 9d · 2026-09-09 | 66° | 92° | 79° | — | 82° | — | — | 66–92° |
| 8d · 2026-09-10 | 71° | 70° | 70° | 72° | 76° | — | — | 70–76° |
| 7d · 2026-09-11 | 74° | 75° | 67° | 71° | 81° | — | — | 67–81° |
| 6d · 2026-09-12 | 73° | 69° | 83° | 72° | 72° | 70° | — | 69–83° |
| 5d · 2026-09-13 | 71° | 72° | 72° | 76° | 77° | 81° | 76° | 71–81° |
| 4d · 2026-09-14 | 70° | 74° | 75° | 76° | 82° | 74° | 76° | 70–82° |
| 3d · 2026-09-15 | 71° | 72° | 74° | 76° | 80° | 76° | 74° | 71–80° |
| 2d · 2026-09-16 | 72° | 75° | 74° | 79° | 78° | 76° | 73° | 72–79° |
| 1d · 2026-09-17 | 72° | 73° | 73° | 76° | 74° | 73° | 72° | 72–76° |
| 0d · 2026-09-18 | 70° | 73° | 72° | 73° | 74° | 72° | 72° | 70–74° |
| actual | 72° |
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.