Was the forecast right for Boston on Tue Sep 1?
Boston, Massachusetts · daily high temperature in °F · forecasts from each model's archived runs, verified against the BOS observations
12 days out, 4 models put Boston's Tue Sep 1 high anywhere from 69° to 90°; by the final call the field had settled to a median of 68°. The day verified at 69° against the BOS observations, with 0.26 in of precipitation — showers.
GEM landed closest, off by 0.0°. UKMO ran 2° hot.
What every model said, at every lead
Daily-high calls for Tue Sep 1 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 |
|---|---|---|---|---|---|---|---|---|
| 12d · 2026-08-20 | 74° | 69° | 70° | — | 90° | — | — | 69–90° |
| 11d · 2026-08-21 | 76° | 87° | 73° | — | 93° | — | — | 73–93° |
| 10d · 2026-08-22 | 75° | 80° | 73° | — | 78° | — | — | 73–80° |
| 9d · 2026-08-23 | 77° | 84° | 78° | — | 66° | — | — | 66–84° |
| 8d · 2026-08-24 | 82° | 77° | 71° | 72° | 72° | — | — | 71–82° |
| 7d · 2026-08-25 | 82° | 84° | 87° | 76° | 87° | — | — | 76–87° |
| 6d · 2026-08-26 | 73° | 73° | 82° | 72° | 69° | 70° | — | 69–82° |
| 5d · 2026-08-27 | 72° | 79° | 80° | 72° | 66° | 76° | 80° | 66–80° |
| 4d · 2026-08-28 | 73° | 71° | 77° | 70° | 74° | 72° | 73° | 70–77° |
| 3d · 2026-08-29 | 71° | 70° | 80° | 79° | 70° | 69° | 74° | 69–80° |
| 2d · 2026-08-30 | 67° | 67° | 73° | 70° | 70° | 69° | 71° | 67–73° |
| 1d · 2026-08-31 | 68° | 68° | 71° | 73° | 69° | 67° | 72° | 67–73° |
| 0d · 2026-09-01 | 68° | 68° | 67° | 69° | 68° | 68° | 71° | 67–71° |
| actual | 69° |
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.