Was the forecast right for Chicago on Mon Aug 3?
Chicago, Illinois · daily high temperature in °F · forecasts from each model's archived runs, verified against the ECMWF IFS analysis
8 days out, 5 models put Chicago's Mon Aug 3 high anywhere from 80° to 91°;by the final call, the day before, the field had settled to a median of 77°. The day verified at 78° against the ECMWF IFS analysis — cloudy.
GEM landed closest, off by 1.1°. GFS ran 6° cool.
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 |
|---|---|---|---|---|---|---|---|---|
| 8d · 2026-07-26 | 80° | 83° | 82° | 80° | 91° | — | — | 80–91° |
| 7d · 2026-07-27 | 80° | 79° | 82° | 82° | 80° | — | — | 79–82° |
| 6d · 2026-07-28 | 79° | 76° | 74° | 80° | 77° | 79° | 81° | 74–81° |
| 5d · 2026-07-29 | 78° | 74° | 77° | 80° | 79° | 78° | 78° | 74–80° |
| 4d · 2026-07-30 | 75° | 74° | 74° | 78° | 73° | 78° | 76° | 73–78° |
| 3d · 2026-07-31 | 76° | 73° | 74° | 76° | 74° | 78° | 78° | 73–78° |
| 2d · 2026-08-01 | 76° | 75° | 75° | 77° | 76° | 78° | 78° | 75–78° |
| 1d · 2026-08-02 | 76° | 77° | 76° | 79° | 73° | 81° | 80° | 73–81° |
| 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 the ECMWF IFS analysis (temperature_2m_max). The actual values are the ones in hand when this receipt was settled, usually 2 days after the date; a correction published after that is not carried into it. Archive depth varies by city; receipts exist only for dates the archive watched arrive.