Was the forecast right for Boston on Mon Aug 31?
Boston, Massachusetts · daily high temperature in °F · forecasts from each model's archived runs, verified against the BOS observations
11 days out, 4 models put Boston's Mon Aug 31 high anywhere from 68° to 87°; by the final call the field had settled to a median of 75°. The day verified at 73° against the BOS observations — drizzle.
UKMO landed closest, off by 1.1°. AIGFS ran 6° hot.
What every model said, at every lead
Daily-high calls for Mon Aug 31 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 |
|---|---|---|---|---|---|---|---|---|
| 11d · 2026-08-20 | 78° | 68° | 71° | — | 87° | — | — | 68–87° |
| 10d · 2026-08-21 | 76° | 84° | 74° | — | 85° | — | — | 74–85° |
| 9d · 2026-08-22 | 74° | 78° | 73° | — | 74° | — | — | 73–78° |
| 8d · 2026-08-23 | 79° | 79° | 83° | 78° | 81° | — | — | 78–83° |
| 7d · 2026-08-24 | 78° | 82° | 83° | 77° | 76° | — | — | 76–83° |
| 6d · 2026-08-25 | 78° | 88° | 88° | 78° | 82° | 90° | — | 78–90° |
| 5d · 2026-08-26 | 76° | 77° | 84° | 77° | 74° | 80° | 86° | 74–86° |
| 4d · 2026-08-27 | 75° | 78° | 80° | 74° | 73° | 81° | 77° | 73–81° |
| 3d · 2026-08-28 | 75° | 80° | 75° | 75° | 72° | 77° | 73° | 72–80° |
| 2d · 2026-08-29 | 76° | 78° | 75° | 76° | 74° | 74° | 78° | 74–78° |
| 1d · 2026-08-30 | 75° | 79° | 73° | 77° | 75° | 74° | 74° | 73–79° |
| 0d · 2026-08-31 | 75° | 79° | 75° | 75° | 76° | 72° | 74° | 72–79° |
| actual | 73° |
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 the BOS observations. Archive depth varies by city; receipts exist only for dates the archive watched arrive.