Was the forecast right for Boston on Mon Sep 7?
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 Mon Sep 7 high anywhere from 73° to 82°;by the final call, the day before, the field had settled to a median of 79°. The day verified at 82° against the BOS observations — partly cloudy.
GEM landed closest, off by 0.0°. GFS ran 5° cool.
What every model said, at every lead
Daily-high calls for Mon Sep 7 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 · 2026-08-23 | — | 79° | — | — | 76° | — | — | 76–79° |
| 14d · 2026-08-24 | 82° | 79° | 80° | — | 73° | — | — | 73–82° |
| 13d · 2026-08-25 | 79° | 82° | 83° | — | 72° | — | — | 72–83° |
| 12d · 2026-08-26 | 83° | 77° | 71° | — | 73° | — | — | 71–83° |
| 11d · 2026-08-27 | 74° | 90° | 82° | — | 80° | — | — | 74–90° |
| 10d · 2026-08-28 | 70° | 74° | 84° | — | 73° | — | — | 70–84° |
| 9d · 2026-08-29 | 74° | 78° | 69° | 72° | 73° | — | — | 69–78° |
| 8d · 2026-08-30 | 78° | 75° | 78° | 74° | 66° | — | — | 66–78° |
| 7d · 2026-08-31 | 76° | 79° | 78° | 75° | 69° | — | — | 69–79° |
| 6d · 2026-09-01 | 77° | 73° | 74° | 75° | 71° | 75° | 76° | 71–77° |
| 5d · 2026-09-02 | 77° | 74° | 78° | 75° | 70° | 76° | 80° | 70–80° |
| 4d · 2026-09-03 | 76° | 76° | 74° | 74° | 75° | 80° | 79° | 74–80° |
| 3d · 2026-09-04 | 77° | 77° | 78° | 79° | 78° | 80° | 80° | 77–80° |
| 2d · 2026-09-05 | 76° | 77° | 78° | 78° | 77° | 79° | 79° | 76–79° |
| 1d · 2026-09-06 | 77° | 77° | 79° | 82° | 77° | 80° | 79° | 77–82° |
| actual | 82° |
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.