Was the forecast right for Boston on Tue Aug 11?
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 Tue Aug 11 high anywhere from 66° to 90°; by the final call the field had settled to a median of 88°. ERA5 says the day verified at 87° — drizzle.
UKMO landed closest, off by 0.4°. AIGFS ran 2° hot.
What every model said, at every lead
Daily-high calls for Tue Aug 11 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 · 2026-07-27 | — | 83° | — | — | 74° | — | — | 74–83° |
| 14d · 2026-07-28 | 82° | 81° | — | — | 70° | — | — | 70–82° |
| 13d · 2026-07-29 | 80° | 70° | 90° | — | 66° | — | — | 66–90° |
| 12d · 2026-07-30 | 81° | 84° | 84° | — | 77° | — | — | 77–84° |
| 11d · 2026-07-31 | 85° | 84° | 84° | — | 86° | — | — | 84–86° |
| 10d · 2026-08-01 | 78° | 83° | 76° | — | 92° | — | — | 76–92° |
| 9d · 2026-08-02 | 82° | 82° | 73° | — | 75° | — | — | 73–82° |
| 8d · 2026-08-03 | 84° | 88° | 94° | 78° | 75° | — | — | 75–94° |
| 7d · 2026-08-04 | 84° | 85° | 83° | 87° | 87° | — | — | 83–87° |
| 6d · 2026-08-05 | 82° | 87° | 92° | 84° | 80° | 88° | — | 80–92° |
| 5d · 2026-08-06 | 82° | 88° | 82° | 90° | 90° | 87° | 83° | 82–90° |
| 4d · 2026-08-07 | 82° | 81° | 92° | 87° | 89° | 88° | 82° | 81–92° |
| 3d · 2026-08-08 | 86° | 90° | 88° | 85° | 87° | 86° | 85° | 85–90° |
| 2d · 2026-08-09 | 86° | 90° | 90° | 87° | 88° | 86° | 84° | 84–90° |
| 1d · 2026-08-10 | 85° | 90° | 90° | 87° | 90° | 89° | 89° | 85–90° |
| 0d · 2026-08-11 | 85° | 89° | 89° | 88° | 88° | 88° | 87° | 85–89° |
| 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.