Was the forecast right for Boston on Tue Sep 15?
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 Tue Sep 15 high anywhere from 65° to 94°; by the final call the field had settled to a median of 66°. The day verified at 66° against the BOS observations — partly cloudy.
ICON landed closest, off by 0.1°. GFS ran 4° cold.
What every model said, at every lead
Daily-high calls for Tue Sep 15 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 · 2026-08-31 | — | 80° | — | — | 84° | — | — | 80–84° |
| 14d · 2026-09-01 | 67° | 72° | — | — | 63° | — | — | 63–72° |
| 13d · 2026-09-02 | 88° | 65° | 92° | — | 94° | — | — | 65–94° |
| 12d · 2026-09-03 | 76° | 92° | 77° | — | 86° | — | — | 76–92° |
| 11d · 2026-09-04 | 85° | 72° | 68° | — | 65° | — | — | 65–85° |
| 10d · 2026-09-05 | 72° | 80° | 71° | — | 92° | — | — | 71–92° |
| 9d · 2026-09-06 | 69° | 86° | 85° | — | 83° | — | — | 69–86° |
| 8d · 2026-09-07 | 72° | 67° | 76° | 65° | 85° | — | — | 65–85° |
| 7d · 2026-09-08 | 69° | 66° | 73° | 65° | 70° | — | — | 65–73° |
| 6d · 2026-09-09 | 68° | 70° | 83° | 69° | 84° | 82° | — | 68–84° |
| 5d · 2026-09-10 | 67° | 73° | 69° | 62° | 72° | 67° | 72° | 62–73° |
| 4d · 2026-09-11 | 66° | 68° | 66° | 68° | 61° | 65° | 68° | 61–68° |
| 3d · 2026-09-12 | 67° | 68° | 65° | 65° | 63° | 67° | 67° | 63–68° |
| 2d · 2026-09-13 | 67° | 69° | 66° | 66° | 63° | 66° | 68° | 63–69° |
| 1d · 2026-09-14 | 66° | 69° | 66° | 67° | 62° | 66° | 66° | 62–69° |
| 0d · 2026-09-15 | 66° | 67° | 65° | 66° | 62° | 66° | 65° | 62–67° |
| actual | 66° |
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.