Was the forecast right for Boston on Sat Aug 8?
Boston, Massachusetts · daily high temperature in °F · forecasts from each model's archived runs, verified against ERA5
12 days out, 4 models put Boston's Sat Aug 8 high anywhere from 82° to 86°; by the final call the field had settled to a median of 91°. ERA5 says the day verified at 93° with 0.18 in of precipitation — rain.
GEM landed closest, off by 1.4°. AIFS ran 6° cold.
What every model said, at every lead
Daily-high calls for Sat Aug 8 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 |
|---|---|---|---|---|---|---|---|---|
| 12d · 2026-07-27 | 86° | 82° | 85° | — | 83° | — | — | 82–86° |
| 11d · 2026-07-28 | 88° | 85° | 87° | — | 80° | — | — | 80–88° |
| 10d · 2026-07-29 | 84° | 93° | 84° | — | 96° | — | — | 84–96° |
| 9d · 2026-07-30 | 83° | 85° | 80° | — | 70° | — | — | 70–85° |
| 8d · 2026-07-31 | 84° | 94° | 79° | 88° | 89° | — | — | 79–94° |
| 7d · 2026-08-01 | 86° | 94° | 87° | 86° | 89° | — | — | 86–94° |
| 6d · 2026-08-02 | 79° | 95° | 87° | 89° | 78° | 88° | — | 78–95° |
| 5d · 2026-08-03 | 83° | 92° | 87° | 88° | 90° | 88° | 85° | 83–92° |
| 4d · 2026-08-04 | 85° | 91° | 89° | 85° | 85° | 89° | 90° | 85–91° |
| 3d · 2026-08-05 | 86° | 91° | 90° | 87° | 86° | 90° | 92° | 86–92° |
| 2d · 2026-08-06 | 85° | 91° | 89° | 92° | 86° | 91° | 88° | 85–92° |
| 1d · 2026-08-07 | 86° | 91° | 91° | 90° | 91° | 91° | 87° | 86–91° |
| 0d · 2026-08-08 | 87° | 92° | 91° | 92° | 91° | 92° | 91° | 87–92° |
| actual | 93° |
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.