Was the forecast right for Boston on Thu Sep 3?
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 3 high anywhere from 68° to 79°; by the final call the field had settled to a median of 78°. The day verified at 73° against the BOS observations, with 0.46 in of precipitation — showers.
AIFS landed closest, off by 3.5°. ECMWF ran 9° hot.
What every model said, at every lead
Daily-high calls for Thu Sep 3 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 |
|---|---|---|---|---|---|---|---|---|
| 14d · 2026-08-20 | 75° | 77° | — | — | 65° | — | — | 65–77° |
| 13d · 2026-08-21 | 74° | 79° | 74° | — | 68° | — | — | 68–79° |
| 12d · 2026-08-22 | 75° | 71° | 80° | — | 67° | — | — | 67–80° |
| 11d · 2026-08-23 | 82° | 71° | 70° | — | 68° | — | — | 68–82° |
| 10d · 2026-08-24 | 78° | 62° | 66° | — | 65° | — | — | 62–78° |
| 9d · 2026-08-25 | 78° | 72° | 84° | — | 68° | — | — | 68–84° |
| 8d · 2026-08-26 | 80° | 71° | 90° | 73° | 69° | — | — | 69–90° |
| 7d · 2026-08-27 | 79° | 70° | 70° | 78° | 68° | — | — | 68–79° |
| 6d · 2026-08-28 | 74° | 85° | 85° | 69° | 86° | 70° | — | 69–86° |
| 5d · 2026-08-29 | 80° | 84° | 77° | 73° | 66° | 88° | 82° | 66–88° |
| 4d · 2026-08-30 | 78° | 84° | 80° | 66° | 78° | 76° | 70° | 66–84° |
| 3d · 2026-08-31 | 77° | 80° | 78° | 72° | 78° | 83° | 78° | 72–83° |
| 2d · 2026-09-01 | 73° | 78° | 74° | 75° | 76° | 77° | 72° | 72–78° |
| 1d · 2026-09-02 | 77° | 79° | 78° | 78° | 76° | 77° | 81° | 76–81° |
| 0d · 2026-09-03 | 76° | 78° | 82° | 79° | 77° | 77° | 78° | 76–82° |
| actual | 73° |
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.