Was the forecast right for Boston on Wed Aug 5?
Boston, Massachusetts · daily high temperature · forecasts from each model's archived runs, verified against ERA5
9 days out, 4 models put Boston's Wed Aug 5 high anywhere from 80° to 90°; by the final call the field had settled to a median of 88°. ERA5 says the day verified at 87° — cloudy.
ICON landed closest, off by 0.3°. AIFS ran 3° cold.
What every model said, at every lead
Daily-high calls for Wed Aug 5 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 |
|---|---|---|---|---|---|---|---|---|
| 9d · 2026-07-27 | 80° | 90° | 84° | — | 85° | — | — | 80–90° |
| 8d · 2026-07-28 | 81° | 85° | 81° | 80° | 71° | — | — | 71–85° |
| 7d · 2026-07-29 | 85° | 84° | 79° | 86° | 83° | — | — | 79–86° |
| 6d · 2026-07-30 | 82° | 88° | 74° | 88° | 82° | 86° | — | 74–88° |
| 5d · 2026-07-31 | 84° | 88° | 79° | 71° | 72° | 73° | 78° | 71–88° |
| 4d · 2026-08-01 | 80° | 87° | 82° | 85° | 82° | 80° | 83° | 80–87° |
| 3d · 2026-08-02 | 80° | 83° | 85° | 84° | 77° | 78° | 90° | 77–90° |
| 2d · 2026-08-03 | 82° | 82° | 86° | 84° | 76° | 84° | 90° | 76–90° |
| 1d · 2026-08-04 | 83° | 86° | 87° | 90° | 86° | 89° | 90° | 83–90° |
| 0d · 2026-08-05 | 84° | 87° | 88° | 90° | 88° | 87° | 90° | 84–90° |
| actual | 87° |
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.