Was the forecast right for Boston on Tue Sep 8?
Boston, Massachusetts · daily high temperature in °C · forecasts from each model's archived runs, verified against the BOS observations
13 days out, 4 models put Boston's Tue Sep 8 high anywhere from 23° to 31°; by the final call the field had settled to a median of 26°. The day verified at 27° against the BOS observations — cloudy.
ICON landed closest, off by 0.4°. GFS ran 2° cold.
What every model said, at every lead
Daily-high calls for Tue Sep 8 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 · 2026-08-24 | — | 26° | — | — | 31° | — | — | 26–31° |
| 14d · 2026-08-25 | 27° | 24° | — | — | 31° | — | — | 24–31° |
| 13d · 2026-08-26 | 25° | 31° | 31° | — | 23° | — | — | 23–31° |
| 12d · 2026-08-27 | 23° | 37° | 30° | — | 22° | — | — | 22–37° |
| 11d · 2026-08-28 | 25° | 35° | 24° | — | 27° | — | — | 24–35° |
| 10d · 2026-08-29 | 26° | 22° | 23° | — | 28° | — | — | 22–28° |
| 9d · 2026-08-30 | 26° | 21° | 21° | — | 21° | — | — | 21–26° |
| 8d · 2026-08-31 | 25° | 26° | 24° | 23° | 26° | — | — | 23–26° |
| 7d · 2026-09-01 | 26° | 27° | 20° | 24° | 20° | — | — | 20–27° |
| 6d · 2026-09-02 | 24° | 27° | 28° | 24° | 27° | 27° | — | 24–28° |
| 5d · 2026-09-03 | 24° | 27° | 27° | 24° | 20° | 29° | 24° | 20–29° |
| 4d · 2026-09-04 | 26° | 27° | 27° | 24° | 24° | 28° | 27° | 24–28° |
| 3d · 2026-09-05 | 25° | 26° | 26° | 25° | 23° | 25° | 27° | 23–27° |
| 2d · 2026-09-06 | 26° | 26° | 28° | 28° | 26° | 27° | 27° | 26–28° |
| 1d · 2026-09-07 | 25° | 26° | 27° | 28° | 23° | 26° | 26° | 23–28° |
| 0d · 2026-09-08 | 25° | 26° | 26° | 28° | 25° | 27° | 25° | 25–28° |
| actual | 27° |
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.