Was the forecast right for Boston on Tue Aug 4?
Boston, Massachusetts · daily high temperature · forecasts from each model's archived runs, verified against ERA5
8 days out, 5 models put Boston's Tue Aug 4 high anywhere from 79° to 82°; by the final call the field had settled to a median of 86°. ERA5 says the day verified at 85° — clear.
AIGFS landed closest, off by 0.0°. UKMO ran 3° hot.
What every model said, at every lead
Daily-high calls for Tue Aug 4 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 · 2026-07-27 | 79° | 82° | 81° | 80° | 79° | — | — | 79–82° |
| 7d · 2026-07-28 | 81° | 84° | 81° | 71° | 74° | — | — | 71–84° |
| 6d · 2026-07-29 | 81° | 84° | 80° | 82° | 85° | 76° | — | 76–85° |
| 5d · 2026-07-30 | 81° | 86° | 80° | 83° | 83° | 86° | 84° | 80–86° |
| 4d · 2026-07-31 | 82° | 85° | 78° | 72° | 77° | 78° | 82° | 72–85° |
| 3d · 2026-08-01 | 81° | 84° | 82° | 84° | 75° | 81° | 84° | 75–84° |
| 2d · 2026-08-02 | 82° | 84° | 84° | 80° | 84° | 87° | 88° | 80–88° |
| 1d · 2026-08-03 | 82° | 84° | 84° | 87° | 83° | 88° | 87° | 82–88° |
| 0d · 2026-08-04 | 82° | 85° | 86° | 87° | 85° | 87° | 88° | 82–88° |
| actual | 85° |
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 ERA5 reanalysis (temperature_2m_max). Archive depth varies by city; receipts exist only for dates the archive watched arrive.