Was the forecast right for Boston on Thu Aug 6?
Boston, Massachusetts · daily high temperature in °F · forecasts from each model's archived runs, verified against ERA5
10 days out, 4 models put Boston's Thu Aug 6 high anywhere from 73° to 90°; by the final call the field had settled to a median of 90°. ERA5 says the day verified at 90° with 0.23 in of precipitation — rain.
GEM landed closest, off by 0.2°. AIFS ran 4° cold.
What every model said, at every lead
Daily-high calls for Thu Aug 6 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 |
|---|---|---|---|---|---|---|---|---|
| 10d · 2026-07-27 | 73° | 90° | 79° | — | 90° | — | — | 73–90° |
| 9d · 2026-07-28 | 86° | 84° | 90° | — | 82° | — | — | 82–90° |
| 8d · 2026-07-29 | 86° | 81° | 84° | 88° | 89° | — | — | 81–89° |
| 7d · 2026-07-30 | 81° | 78° | 86° | 88° | 81° | — | — | 78–88° |
| 6d · 2026-07-31 | 84° | 94° | 81° | 86° | 76° | 68° | — | 68–94° |
| 5d · 2026-08-01 | 85° | 94° | 84° | 90° | 90° | 89° | 91° | 84–94° |
| 4d · 2026-08-02 | 85° | 93° | 88° | 87° | 87° | 90° | 93° | 85–93° |
| 3d · 2026-08-03 | 85° | 91° | 84° | 90° | 86° | 92° | 91° | 84–92° |
| 2d · 2026-08-04 | 85° | 90° | 88° | 91° | 87° | 92° | 90° | 85–92° |
| 1d · 2026-08-05 | 86° | 91° | 89° | 93° | 90° | 92° | 88° | 86–93° |
| 0d · 2026-08-06 | 86° | 91° | 91° | 90° | 90° | 90° | 90° | 86–91° |
| actual | 90° |
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.