Was the forecast right for Boston on Wed Sep 30?
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 Wed Sep 30 high anywhere from 59° to 74°;by the final call, the day before, the field had settled to a median of 70°. The day verified at 66° against the BOS observations, with 0.01 in of precipitation — drizzle.
AIFS landed closest, off by 0.6°. GEM ran 6° warm.
What every model said, at every lead
Daily-high calls for Wed Sep 30 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 · 2026-09-15 | — | 60° | — | — | 81° | — | — | 60–81° |
| 14d · 2026-09-16 | 67° | 59° | 59° | — | 74° | — | — | 59–74° |
| 13d · 2026-09-17 | 62° | 77° | 74° | — | 61° | — | — | 61–77° |
| 12d · 2026-09-18 | 73° | 69° | 75° | — | 63° | — | — | 63–75° |
| 11d · 2026-09-19 | 63° | 59° | 62° | — | 62° | — | — | 59–63° |
| 10d · 2026-09-20 | 69° | 73° | 64° | — | 72° | — | — | 64–73° |
| 9d · 2026-09-21 | 71° | 75° | 60° | 72° | 67° | — | — | 60–75° |
| 8d · 2026-09-22 | 71° | 77° | 64° | 70° | 74° | — | — | 64–77° |
| 7d · 2026-09-23 | 72° | 76° | 71° | 73° | 67° | — | — | 67–76° |
| 6d · 2026-09-24 | 72° | 72° | 71° | 68° | 68° | 71° | 69° | 68–72° |
| 5d · 2026-09-25 | 70° | 73° | 71° | 66° | 70° | 71° | 68° | 66–73° |
| 4d · 2026-09-26 | 68° | 70° | 67° | 66° | 68° | 70° | 67° | 66–70° |
| 3d · 2026-09-27 | 67° | 70° | 71° | 70° | 68° | 70° | 70° | 67–71° |
| 2d · 2026-09-28 | 67° | 70° | 68° | 70° | 69° | 71° | 70° | 67–71° |
| 1d · 2026-09-29 | 67° | 70° | 69° | 72° | 68° | 71° | 70° | 67–72° |
| actual | 66° |
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.