Was the forecast right for Boston on Sun Aug 30?
Boston, Massachusetts · daily high temperature in °F · forecasts from each model's archived runs, verified against the BOS observations
10 days out, 4 models put Boston's Sun Aug 30 high anywhere from 73° to 88°; by the final call the field had settled to a median of 84°. The day verified at 86° against the BOS observations — drizzle.
ECMWF landed closest, off by 0.1°. AIFS ran 5° cold.
What every model said, at every lead
Daily-high calls for Sun Aug 30 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 · 2026-08-20 | 77° | 73° | 74° | — | 88° | — | — | 73–88° |
| 9d · 2026-08-21 | 72° | 75° | 79° | — | 70° | — | — | 70–79° |
| 8d · 2026-08-22 | 71° | 73° | 72° | 73° | 76° | — | — | 71–76° |
| 7d · 2026-08-23 | 80° | 73° | 79° | 76° | 70° | — | — | 70–80° |
| 6d · 2026-08-24 | 78° | 83° | 82° | 74° | 77° | 79° | — | 74–83° |
| 5d · 2026-08-25 | 80° | 81° | 82° | 75° | 83° | 83° | 84° | 75–84° |
| 4d · 2026-08-26 | 82° | 82° | 84° | 77° | 84° | 84° | 82° | 77–84° |
| 3d · 2026-08-27 | 83° | 83° | 88° | 78° | 86° | 85° | 84° | 78–88° |
| 2d · 2026-08-28 | 80° | 83° | 85° | 84° | 85° | 86° | 86° | 80–86° |
| 1d · 2026-08-29 | 81° | 82° | 86° | 88° | 84° | 86° | 86° | 81–88° |
| 0d · 2026-08-30 | 81° | 83° | 86° | 87° | 84° | 84° | 85° | 81–87° |
| actual | 86° |
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.