Was the forecast right for Chicago on Sun Aug 9?
Chicago, Illinois · daily high temperature in °F · forecasts from each model's archived runs, verified against ERA5
13 days out, 4 models put Chicago's Sun Aug 9 high anywhere from 68° to 92°; by the final call the field had settled to a median of 82°. ERA5 says the day verified at 78° with 0.76 in of precipitation — rain.
AIFS landed closest, off by 0.3°. UKMO ran 14° hot.
What every model said, at every lead
Daily-high calls for Sun Aug 9 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 |
|---|---|---|---|---|---|---|---|---|
| 13d · 2026-07-27 | 83° | 68° | 92° | — | 87° | — | — | 68–92° |
| 12d · 2026-07-28 | 78° | 80° | 100° | — | 98° | — | — | 78–100° |
| 11d · 2026-07-29 | 79° | 77° | 81° | — | 74° | — | — | 74–81° |
| 10d · 2026-07-30 | 82° | 81° | 90° | — | 82° | — | — | 81–90° |
| 9d · 2026-07-31 | 82° | 76° | 84° | — | 90° | — | — | 76–90° |
| 8d · 2026-08-01 | 82° | 80° | 84° | 74° | 76° | — | — | 74–84° |
| 7d · 2026-08-02 | 81° | 80° | 93° | 84° | 93° | — | — | 80–93° |
| 6d · 2026-08-03 | 84° | 83° | 87° | 86° | 86° | 86° | — | 83–87° |
| 5d · 2026-08-04 | 82° | 82° | 86° | 79° | 85° | 82° | 93° | 79–93° |
| 4d · 2026-08-05 | 84° | 84° | 85° | 85° | 89° | 87° | 91° | 84–91° |
| 3d · 2026-08-06 | 78° | 80° | 84° | 78° | 70° | 84° | 87° | 70–87° |
| 2d · 2026-08-07 | 79° | 83° | 84° | 79° | 86° | 82° | 83° | 79–86° |
| 1d · 2026-08-08 | 79° | 79° | 83° | 84° | 88° | 80° | 89° | 79–89° |
| 0d · 2026-08-09 | 78° | 82° | 87° | 82° | 86° | 80° | 92° | 78–92° |
| actual | 78° |
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 ERA5 reanalysis (temperature_2m_max). Archive depth varies by city; receipts exist only for dates the archive watched arrive.