Was the forecast right for Boston on Wed Sep 2?
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 2 high anywhere from 71° to 78°; by the final call the field had settled to a median of 72°. The day verified at 72° against the BOS observations — cloudy.
ECMWF landed closest, off by 0.3°. GFS ran 2° cold.
What every model said, at every lead
Daily-high calls for Wed Sep 2 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 |
|---|---|---|---|---|---|---|---|---|
| 13d · 2026-08-20 | 75° | 71° | 72° | — | 78° | — | — | 71–78° |
| 12d · 2026-08-21 | 80° | 78° | 73° | — | 83° | — | — | 73–83° |
| 11d · 2026-08-22 | 75° | 69° | 78° | — | 69° | — | — | 69–78° |
| 10d · 2026-08-23 | 82° | 83° | 73° | — | 66° | — | — | 66–83° |
| 9d · 2026-08-24 | 85° | 68° | 73° | — | 64° | — | — | 64–85° |
| 8d · 2026-08-25 | 82° | 80° | 82° | 84° | 70° | — | — | 70–84° |
| 7d · 2026-08-26 | 81° | 86° | 92° | 76° | 71° | — | — | 71–92° |
| 6d · 2026-08-27 | 74° | 85° | 71° | 73° | 65° | 89° | — | 65–89° |
| 5d · 2026-08-28 | 73° | 76° | 80° | 70° | 69° | 71° | 81° | 69–81° |
| 4d · 2026-08-29 | 71° | 70° | 72° | 69° | 68° | 71° | 79° | 68–79° |
| 3d · 2026-08-30 | 70° | 72° | 72° | 68° | 68° | 72° | 70° | 68–72° |
| 2d · 2026-08-31 | 71° | 73° | 73° | 71° | 70° | 71° | 71° | 70–73° |
| 1d · 2026-09-01 | 72° | 73° | 72° | 74° | 70° | 72° | 71° | 70–74° |
| 0d · 2026-09-02 | 71° | 74° | 72° | 73° | 70° | 72° | 71° | 70–74° |
| actual | 72° |
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.