Was the forecast right for Chicago on Mon Aug 3?
Chicago, Illinois · daily high temperature · forecasts from each model's archived runs, verified against ERA5
7 days out, 5 models put Chicago's Mon Aug 3 high anywhere from 80° to 84°; by the final call the field had settled to a median of 78°. ERA5 says the day verified at 78° — cloudy.
GEM landed closest, off by 0.1°. GFS ran 6° cold.
What every model said, at every lead
Daily-high calls for Mon Aug 3 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 |
|---|---|---|---|---|---|---|---|---|
| 7d · 2026-07-27 | 80° | 84° | 82° | 80° | 84° | — | — | 80–84° |
| 6d · 2026-07-28 | 75° | 76° | 74° | 79° | 77° | 84° | — | 74–84° |
| 5d · 2026-07-29 | 76° | 75° | 76° | 81° | 77° | 75° | 74° | 74–81° |
| 4d · 2026-07-30 | 76° | 72° | 74° | 78° | 74° | 79° | 78° | 72–79° |
| 3d · 2026-07-31 | 75° | 73° | 72° | 75° | 76° | 76° | 71° | 71–76° |
| 2d · 2026-08-01 | 76° | 74° | 74° | 77° | 75° | 78° | 78° | 74–78° |
| 1d · 2026-08-02 | 76° | 75° | 76° | 79° | 73° | 80° | 78° | 73–80° |
| 0d · 2026-08-03 | 76° | 78° | 76° | 78° | 72° | 81° | 80° | 72–81° |
| 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.