Was the forecast right for Boston on Wed Aug 12?
Boston, Massachusetts · daily high temperature in °F · forecasts from each model's archived runs, verified against ERA5
13 days out, 4 models put Boston's Wed Aug 12 high anywhere from 71° to 81°; by the final call the field had settled to a median of 86°. ERA5 says the day verified at 85° — cloudy.
AIGFS landed closest, off by 0.2°. GEM ran 3° hot.
What every model said, at every lead
Daily-high calls for Wed Aug 12 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 |
|---|---|---|---|---|---|---|---|---|
| 15d · 2026-07-28 | — | 77° | — | — | 72° | — | — | 72–77° |
| 14d · 2026-07-29 | 76° | 77° | — | — | 67° | — | — | 67–77° |
| 13d · 2026-07-30 | 81° | 77° | 79° | — | 71° | — | — | 71–81° |
| 12d · 2026-07-31 | 82° | 74° | 85° | — | 71° | — | — | 71–85° |
| 11d · 2026-08-01 | 74° | 82° | 80° | — | 77° | — | — | 74–82° |
| 10d · 2026-08-02 | 78° | 79° | 88° | — | 72° | — | — | 72–88° |
| 9d · 2026-08-03 | 79° | 84° | 87° | — | 71° | — | — | 71–87° |
| 8d · 2026-08-04 | 81° | 85° | 82° | 83° | 83° | — | — | 81–85° |
| 7d · 2026-08-05 | 82° | 85° | 88° | 82° | 79° | — | — | 79–88° |
| 6d · 2026-08-06 | 81° | 85° | 83° | 81° | 75° | 84° | — | 75–85° |
| 5d · 2026-08-07 | 81° | 84° | 88° | 84° | 80° | 86° | 84° | 80–88° |
| 4d · 2026-08-08 | 82° | 83° | 87° | 83° | 72° | 84° | 84° | 72–87° |
| 3d · 2026-08-09 | 82° | 84° | 88° | 83° | 84° | 85° | 86° | 82–88° |
| 2d · 2026-08-10 | 81° | 84° | 86° | 84° | 79° | 87° | 85° | 79–87° |
| 1d · 2026-08-11 | 83° | 84° | 86° | 85° | 80° | 84° | 79° | 79–86° |
| 0d · 2026-08-12 | 83° | 85° | 86° | 88° | 87° | 86° | 83° | 83–88° |
| 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.