Was the forecast right for Boston on Mon Aug 3?
Boston, Massachusetts · daily high temperature in °F · forecasts from each model's archived runs, verified against the ECMWF IFS analysis
8 days out, 5 models put Boston's Mon Aug 3 high anywhere from 77° to 84°;by the final call, the day before, the field had settled to a median of 80°. The day verified at 76° against the ECMWF IFS analysis, with 1.33 in of precipitation — rain.
AIFS landed closest, off by 1.3°. UKMO ran 4° warm.
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 Boston scoreboard shows them, labelled.
| Lead | AIFS | AIGFS | ECMWF | GEM | GFS | ICON | UKMO | Range |
|---|---|---|---|---|---|---|---|---|
| 8d · 2026-07-26 | 79° | 84° | 83° | 77° | 83° | — | — | 77–84° |
| 7d · 2026-07-27 | 81° | 82° | 83° | 75° | 74° | — | — | 74–83° |
| 6d · 2026-07-28 | 81° | 81° | 82° | 82° | 72° | 79° | 85° | 72–85° |
| 5d · 2026-07-29 | 81° | 82° | 82° | 82° | 76° | 82° | 76° | 76–82° |
| 4d · 2026-07-30 | 78° | 82° | 81° | 82° | 82° | 86° | 88° | 78–88° |
| 3d · 2026-07-31 | 79° | 79° | 81° | 85° | 71° | 81° | 83° | 71–85° |
| 2d · 2026-08-01 | 77° | 78° | 78° | 79° | 79° | 78° | 87° | 77–87° |
| 1d · 2026-08-02 | 78° | 78° | 80° | 80° | 80° | 79° | 81° | 78–81° |
| actual | 76° |
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 Boston — 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.