Was the forecast right for Boston on Thu Sep 17?
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 Thu Sep 17 high anywhere from 64° to 79°; by the final call the field had settled to a median of 78°. The day verified at 76° against the BOS observations — drizzle.
AIFS landed closest, off by 1.4°. UKMO ran 5° hot.
What every model said, at every lead
Daily-high calls for Thu Sep 17 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 · 2026-09-02 | — | 70° | — | — | 88° | — | — | 70–88° |
| 14d · 2026-09-03 | 72° | 79° | — | — | 62° | — | — | 62–79° |
| 13d · 2026-09-04 | 76° | 64° | 68° | — | 79° | — | — | 64–79° |
| 12d · 2026-09-05 | 86° | 80° | 68° | — | 63° | — | — | 63–86° |
| 11d · 2026-09-06 | 79° | 86° | 65° | — | 63° | — | — | 63–86° |
| 10d · 2026-09-07 | 70° | 64° | 72° | — | 61° | — | — | 61–72° |
| 9d · 2026-09-08 | 73° | 80° | 71° | — | 63° | — | — | 63–80° |
| 8d · 2026-09-09 | 81° | 84° | 65° | 74° | 67° | — | — | 65–84° |
| 7d · 2026-09-10 | 76° | 68° | 85° | 79° | 73° | — | — | 68–85° |
| 6d · 2026-09-11 | 76° | 85° | 82° | 74° | 71° | 86° | — | 71–86° |
| 5d · 2026-09-12 | 73° | 79° | 81° | 70° | 79° | 84° | 74° | 70–84° |
| 4d · 2026-09-13 | 76° | 78° | 78° | 74° | 71° | 83° | 74° | 71–83° |
| 3d · 2026-09-14 | 75° | 78° | 78° | 76° | 69° | 79° | 81° | 69–81° |
| 2d · 2026-09-15 | 76° | 79° | 80° | 83° | 70° | 80° | 80° | 70–83° |
| 1d · 2026-09-16 | 77° | 80° | 79° | 86° | 74° | 76° | 78° | 74–86° |
| 0d · 2026-09-17 | 75° | 78° | 79° | 80° | 78° | 78° | 81° | 75–81° |
| actual | 76° |
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.