Was the forecast right for Boston on Thu Sep 10?
Boston, Massachusetts · daily high temperature in °F · forecasts from each model's archived runs, verified against the BOS observations
14 days out, 4 models put Boston's Thu Sep 10 high anywhere from 70° to 87°;by the final call, the day before, the field had settled to a median of 84°. The day verified at 87° against the BOS observations, with 0.01 in of precipitation — drizzle.
GEM landed closest, off by 0.3°. ECMWF ran 3° cool.
What every model said, at every lead
Daily-high calls for Thu Sep 10 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, labeled.
| Lead | AIFS | AIGFS | ECMWF | GEM | GFS | ICON | UKMO | Range |
|---|---|---|---|---|---|---|---|---|
| 15d · 2026-08-26 | — | 80° | — | — | 79° | — | — | 79–80° |
| 14d · 2026-08-27 | 85° | 75° | 87° | — | 70° | — | — | 70–87° |
| 13d · 2026-08-28 | 80° | 86° | 94° | — | 84° | — | — | 80–94° |
| 12d · 2026-08-29 | 77° | 85° | 80° | — | 82° | — | — | 77–85° |
| 11d · 2026-08-30 | 83° | 78° | 69° | — | 68° | — | — | 68–83° |
| 10d · 2026-08-31 | 86° | 88° | 77° | — | 88° | — | — | 77–88° |
| 9d · 2026-09-01 | 83° | 70° | 86° | 84° | 74° | — | — | 70–86° |
| 8d · 2026-09-02 | 83° | 88° | 82° | 82° | 80° | — | — | 80–88° |
| 7d · 2026-09-03 | 77° | 87° | 78° | 83° | 85° | — | — | 77–87° |
| 6d · 2026-09-04 | 83° | 87° | 86° | 82° | 74° | 87° | 88° | 74–88° |
| 5d · 2026-09-05 | 83° | 86° | 84° | 80° | 72° | 86° | 81° | 72–86° |
| 4d · 2026-09-06 | 84° | 85° | 80° | 79° | 86° | 87° | 84° | 79–87° |
| 3d · 2026-09-07 | 83° | 86° | 81° | 86° | 85° | 84° | 86° | 81–86° |
| 2d · 2026-09-08 | 85° | 88° | 85° | 85° | 86° | 85° | 84° | 84–88° |
| 1d · 2026-09-09 | 84° | 88° | 84° | 87° | 84° | 85° | 84° | 84–88° |
| actual | 87° |
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. The actual values are the ones in hand when this day was verified, usually 2 days after the date; a correction published after that is not carried into it. Archive depth varies by city; verified days exist only for dates the archive watched arrive.