Was the forecast right for Chicago on Mon Sep 21?
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 Mon Sep 21 high anywhere from 69° to 82°;by the final call, the day before, the field had settled to a median of 63°. The day verified at 65° against the MDW observations, with 0.02 in of precipitation — drizzle.
ECMWF landed closest, off by 0.2°. AIGFS ran 4° cool.
What every model said, at every lead
Daily-high calls for Mon Sep 21 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 · 2026-09-06 | — | 60° | — | — | 72° | — | — | 60–72° |
| 14d · 2026-09-07 | 69° | 78° | 74° | — | 82° | — | — | 69–82° |
| 13d · 2026-09-08 | 70° | 65° | 65° | — | 68° | — | — | 65–70° |
| 12d · 2026-09-09 | 83° | 70° | 60° | — | 73° | — | — | 60–83° |
| 11d · 2026-09-10 | 64° | 59° | 60° | — | 67° | — | — | 59–67° |
| 10d · 2026-09-11 | 67° | 66° | 79° | — | 80° | — | — | 66–80° |
| 9d · 2026-09-12 | 70° | 62° | 65° | 66° | 74° | — | — | 62–74° |
| 8d · 2026-09-13 | 74° | 67° | 77° | 78° | 60° | — | — | 60–78° |
| 7d · 2026-09-14 | 64° | 68° | 68° | 68° | 61° | — | — | 61–68° |
| 6d · 2026-09-15 | 65° | 62° | 75° | 64° | 74° | 69° | 67° | 62–75° |
| 5d · 2026-09-16 | 65° | 61° | 66° | 66° | 64° | 74° | 67° | 61–74° |
| 4d · 2026-09-17 | 64° | 62° | 63° | 60° | 62° | 64° | 67° | 60–67° |
| 3d · 2026-09-18 | 64° | 62° | 64° | 61° | 63° | 67° | 66° | 61–67° |
| 2d · 2026-09-19 | 64° | 62° | 65° | 65° | 65° | 67° | 66° | 62–67° |
| 1d · 2026-09-20 | 63° | 61° | 65° | 63° | 62° | 65° | 67° | 61–67° |
| actual | 65° |
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.