Was the forecast right for Chicago on Fri Jul 31?
Chicago, Illinois · daily high temperature · forecasts from each model's archived runs, verified against ERA5
4 days out, 7 models put Chicago's Fri Jul 31 high anywhere from 76° to 89°; by the final call the field had settled to a median of 81°. ERA5 says the day verified at 81° with 0.49 in of precipitation — rain.
AIGFS landed closest, off by 0.2°. AIFS ran 4° cold.
What every model said, at every lead
Daily-high calls for Fri Jul 31 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 |
|---|---|---|---|---|---|---|---|---|
| 4d · 2026-07-27 | 80° | 82° | 89° | 84° | 76° | 86° | 86° | 76–89° |
| 3d · 2026-07-28 | 75° | 80° | 88° | 80° | 77° | 84° | 88° | 75–88° |
| 2d · 2026-07-29 | 76° | 77° | 86° | 81° | 73° | 84° | 80° | 73–86° |
| 1d · 2026-07-30 | 79° | 79° | 86° | 82° | 78° | 82° | 82° | 78–86° |
| 0d · 2026-07-31 | 77° | 81° | 82° | 84° | 79° | 82° | 81° | 77–84° |
| actual | 81° |
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.