Was the forecast right for Boston on Fri Sep 11?
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 Fri Sep 11 high anywhere from 69° to 82°; by the final call the field had settled to a median of 77°. The day verified at 79° against the BOS observations — cloudy.
GEM landed closest, off by 0.5°. ICON ran 3° cold.
What every model said, at every lead
Daily-high calls for Fri Sep 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 · 2026-08-27 | — | 76° | — | — | 73° | — | — | 73–76° |
| 14d · 2026-08-28 | 74° | 78° | — | — | 67° | — | — | 67–78° |
| 13d · 2026-08-29 | 82° | 71° | 69° | — | 75° | — | — | 69–82° |
| 12d · 2026-08-30 | 73° | 77° | 64° | — | 70° | — | — | 64–77° |
| 11d · 2026-08-31 | 74° | 82° | 72° | — | 69° | — | — | 69–82° |
| 10d · 2026-09-01 | 76° | 71° | 77° | — | 64° | — | — | 64–77° |
| 9d · 2026-09-02 | 78° | 71° | 77° | — | 66° | — | — | 66–78° |
| 8d · 2026-09-03 | 69° | 74° | 76° | 73° | 70° | — | — | 69–76° |
| 7d · 2026-09-04 | 76° | 71° | 67° | 68° | 70° | — | — | 67–76° |
| 6d · 2026-09-05 | 77° | 81° | 71° | 70° | 70° | 80° | — | 70–81° |
| 5d · 2026-09-06 | 74° | 79° | 76° | 70° | 74° | 75° | 78° | 70–79° |
| 4d · 2026-09-07 | 73° | 78° | 77° | 73° | 74° | 78° | 78° | 73–78° |
| 3d · 2026-09-08 | 75° | 75° | 78° | 77° | 73° | 72° | 76° | 72–78° |
| 2d · 2026-09-09 | 76° | 77° | 77° | 78° | 75° | 76° | 77° | 75–78° |
| 1d · 2026-09-10 | 76° | 78° | 77° | 77° | 77° | 75° | 78° | 75–78° |
| 0d · 2026-09-11 | 76° | 77° | 78° | 78° | 77° | 76° | 78° | 76–78° |
| actual | 79° |
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.