Was the forecast right for Boston on Sun Sep 13?
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 Sun Sep 13 high anywhere from 73° to 76°; by the final call the field had settled to a median of 68°. The day verified at 70° against the BOS observations, with 0.84 in of precipitation — thunderstorms.
ICON landed closest, off by 0.0°. AIGFS ran 3° cold.
What every model said, at every lead
Daily-high calls for Sun Sep 13 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 · 2026-08-29 | — | 73° | — | — | 72° | — | — | 72–73° |
| 14d · 2026-08-30 | 77° | 73° | — | — | 64° | — | — | 64–77° |
| 13d · 2026-08-31 | 76° | 74° | 74° | — | 73° | — | — | 73–76° |
| 12d · 2026-09-01 | 86° | 82° | 86° | — | 77° | — | — | 77–86° |
| 11d · 2026-09-02 | 70° | 92° | 67° | — | 81° | — | — | 67–92° |
| 10d · 2026-09-03 | 69° | 82° | 70° | — | 78° | — | — | 69–82° |
| 9d · 2026-09-04 | 79° | 76° | 76° | — | 71° | — | — | 71–79° |
| 8d · 2026-09-05 | 77° | 75° | 77° | 81° | 81° | — | — | 75–81° |
| 7d · 2026-09-06 | 82° | 87° | 84° | 76° | 80° | — | — | 76–87° |
| 6d · 2026-09-07 | 78° | 83° | 81° | 76° | 82° | 84° | — | 76–84° |
| 5d · 2026-09-08 | 76° | 78° | 80° | 74° | 80° | 79° | 83° | 74–83° |
| 4d · 2026-09-09 | 71° | 66° | 75° | 67° | 73° | 78° | 82° | 66–82° |
| 3d · 2026-09-10 | 71° | 69° | 73° | 70° | 77° | 76° | 74° | 69–77° |
| 2d · 2026-09-11 | 71° | 66° | 76° | 77° | 67° | 74° | 76° | 66–77° |
| 1d · 2026-09-12 | 70° | 66° | 72° | 71° | 67° | 71° | 69° | 66–72° |
| 0d · 2026-09-13 | 68° | 67° | 71° | 70° | 68° | 70° | 68° | 67–71° |
| actual | 70° |
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.