Was the forecast right for Chicago on Sat Aug 15?
Chicago, Illinois · daily high temperature in °F · forecasts from each model's archived runs, verified against the ECMWF IFS analysis
13 days out, 4 models put Chicago's Sat Aug 15 high anywhere from 83° to 91°; by the final call the field had settled to a median of 79°. The ECMWF IFS analysis says the day verified at 84° with 0.64 in of precipitation — thunderstorms.
GEM landed closest, off by 2.9°. AIGFS ran 8° cold.
What every model said, at every lead
Daily-high calls for Sat Aug 15 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 · 2026-07-31 | — | 69° | — | — | 76° | — | — | 69–76° |
| 14d · 2026-08-01 | 80° | 84° | — | — | 90° | — | — | 80–90° |
| 13d · 2026-08-02 | 83° | 83° | 91° | — | 89° | — | — | 83–91° |
| 12d · 2026-08-03 | 82° | 75° | 77° | — | 74° | — | — | 74–82° |
| 11d · 2026-08-04 | 75° | 76° | 86° | — | 76° | — | — | 75–86° |
| 10d · 2026-08-05 | 69° | 75° | 74° | — | 69° | — | — | 69–75° |
| 9d · 2026-08-06 | 72° | 70° | 69° | — | 66° | — | — | 66–72° |
| 8d · 2026-08-07 | 71° | 70° | 83° | 74° | 77° | — | — | 70–83° |
| 7d · 2026-08-08 | 74° | 73° | 76° | 74° | 80° | — | — | 73–80° |
| 6d · 2026-08-09 | 75° | 66° | 80° | 76° | 75° | 79° | — | 66–80° |
| 5d · 2026-08-10 | 73° | 69° | 91° | 76° | 86° | 76° | 89° | 69–91° |
| 4d · 2026-08-11 | 77° | 77° | 78° | 80° | 87° | 90° | 78° | 77–90° |
| 3d · 2026-08-12 | 82° | 82° | 80° | 73° | 87° | 86° | 82° | 73–87° |
| 2d · 2026-08-13 | 77° | 76° | 85° | 78° | 87° | 84° | 86° | 76–87° |
| 1d · 2026-08-14 | 77° | 76° | 86° | 81° | 76° | 80° | 87° | 76–87° |
| 0d · 2026-08-15 | 78° | 76° | 80° | 81° | 79° | 79° | 77° | 76–81° |
| actual | 84° |
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 ECMWF IFS analysis (temperature_2m_max). Archive depth varies by city; receipts exist only for dates the archive watched arrive.