Was the forecast right for Boston on Sat Sep 5?
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 Sat Sep 5 high anywhere from 61° to 78°;by the final call, the day before, the field had settled to a median of 70°. The day verified at 73° against the BOS observations — drizzle.
GEM landed closest, off by 0.7°. ECMWF ran 4° cool.
What every model said, at every lead
Daily-high calls for Sat Sep 5 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 · 2026-08-21 | — | 64° | — | — | 67° | — | — | 64–67° |
| 14d · 2026-08-22 | 74° | 78° | 78° | — | 61° | — | — | 61–78° |
| 13d · 2026-08-23 | 75° | 80° | 78° | — | 69° | — | — | 69–80° |
| 12d · 2026-08-24 | 76° | 68° | 80° | — | 68° | — | — | 68–80° |
| 11d · 2026-08-25 | 75° | 82° | 80° | — | 72° | — | — | 72–82° |
| 10d · 2026-08-26 | 72° | 72° | 85° | — | 68° | — | — | 68–85° |
| 9d · 2026-08-27 | 75° | 84° | 72° | 78° | 79° | — | — | 72–84° |
| 8d · 2026-08-28 | 76° | 73° | 72° | 76° | 76° | — | — | 72–76° |
| 7d · 2026-08-29 | 74° | 76° | 66° | 68° | 72° | — | — | 66–76° |
| 6d · 2026-08-30 | 69° | 70° | 68° | 70° | 70° | 76° | 74° | 68–76° |
| 5d · 2026-08-31 | 72° | 71° | 69° | 68° | 73° | 71° | 71° | 68–73° |
| 4d · 2026-09-01 | 71° | 72° | 70° | 69° | 71° | 75° | 78° | 69–78° |
| 3d · 2026-09-02 | 69° | 68° | 68° | 73° | 68° | 72° | 74° | 68–74° |
| 2d · 2026-09-03 | 70° | 71° | 70° | 74° | 69° | 74° | 75° | 69–75° |
| 1d · 2026-09-04 | 70° | 69° | 69° | 72° | 69° | 71° | 75° | 69–75° |
| 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. The actual values are the ones in hand when this receipt was settled, usually 2 days after the date; a correction published after that is not carried into it. Archive depth varies by city; receipts exist only for dates the archive watched arrive.