Was the forecast right for Boston on Mon Aug 10?
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 Mon Aug 10 high anywhere from 78° to 93°; by the final call the field had settled to a median of 88°. ERA5 says the day verified at 85° — cloudy.
ICON landed closest, off by 0.4°. ECMWF ran 4° hot.
What every model said, at every lead
Daily-high calls for Mon Aug 10 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 |
|---|---|---|---|---|---|---|---|---|
| 14d · 2026-07-27 | 82° | 78° | — | — | 78° | — | — | 78–82° |
| 13d · 2026-07-28 | 78° | 84° | 82° | — | 93° | — | — | 78–93° |
| 12d · 2026-07-29 | 82° | 86° | 91° | — | 75° | — | — | 75–91° |
| 11d · 2026-07-30 | 82° | 89° | 89° | — | 74° | — | — | 74–89° |
| 10d · 2026-07-31 | 86° | 78° | 89° | — | 90° | — | — | 78–90° |
| 9d · 2026-08-01 | 85° | 91° | 82° | — | 84° | — | — | 82–91° |
| 8d · 2026-08-02 | 86° | 89° | 86° | 84° | 92° | — | — | 84–92° |
| 7d · 2026-08-03 | 87° | 94° | 90° | 90° | 90° | — | — | 87–94° |
| 6d · 2026-08-04 | 86° | 94° | 86° | 88° | 88° | 92° | — | 86–94° |
| 5d · 2026-08-05 | 87° | 94° | 89° | 89° | 90° | 93° | 92° | 87–94° |
| 4d · 2026-08-06 | 87° | 89° | 89° | 88° | 88° | 92° | 91° | 87–92° |
| 3d · 2026-08-07 | 84° | 89° | 90° | 86° | 82° | 87° | 90° | 82–90° |
| 2d · 2026-08-08 | 86° | 89° | 90° | 88° | 82° | 90° | 92° | 82–92° |
| 1d · 2026-08-09 | 86° | 89° | 91° | 94° | 91° | 92° | 92° | 86–94° |
| 0d · 2026-08-10 | 84° | 88° | 89° | 88° | 88° | 85° | 86° | 84–89° |
| 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.