Was the forecast right for Boston on Wed Sep 9?
Boston, Massachusetts · daily high temperature in °F · forecasts from each model's archived runs, verified against the BOS observations
13 days out, 4 models put Boston's Wed Sep 9 high anywhere from 69° to 90°; by the final call the field had settled to a median of 79°. The day verified at 76° against the BOS observations, with 0.02 in of precipitation — drizzle.
AIFS landed closest, off by 1.0°. GEM ran 6° hot.
What every model said, at every lead
Daily-high calls for Wed Sep 9 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 · 2026-08-25 | — | 74° | — | — | 77° | — | — | 74–77° |
| 14d · 2026-08-26 | 71° | 77° | — | — | 76° | — | — | 71–77° |
| 13d · 2026-08-27 | 69° | 81° | 90° | — | 75° | — | — | 69–90° |
| 12d · 2026-08-28 | 76° | 93° | 81° | — | 76° | — | — | 76–93° |
| 11d · 2026-08-29 | 79° | 70° | 76° | — | 94° | — | — | 70–94° |
| 10d · 2026-08-30 | 80° | 69° | 70° | — | 74° | — | — | 69–80° |
| 9d · 2026-08-31 | 78° | 84° | 79° | — | 77° | — | — | 77–84° |
| 8d · 2026-09-01 | 79° | 73° | 76° | 77° | 60° | — | — | 60–79° |
| 7d · 2026-09-02 | 76° | 89° | 76° | 67° | 74° | — | — | 67–89° |
| 6d · 2026-09-03 | 69° | 82° | 74° | 76° | 74° | 88° | — | 69–88° |
| 5d · 2026-09-04 | 77° | 81° | 77° | 75° | 81° | 73° | 81° | 73–81° |
| 4d · 2026-09-05 | 77° | 78° | 76° | 76° | 79° | 84° | 77° | 76–84° |
| 3d · 2026-09-06 | 76° | 77° | 80° | 75° | 77° | 71° | 84° | 71–84° |
| 2d · 2026-09-07 | 76° | 79° | 80° | 81° | 80° | 78° | 83° | 76–83° |
| 1d · 2026-09-08 | 75° | 78° | 81° | 84° | 76° | 79° | 81° | 75–84° |
| 0d · 2026-09-09 | 75° | 79° | 79° | 82° | 78° | 79° | 81° | 75–82° |
| actual | 76° |
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.