Was the forecast right for Boston on Thu Aug 27?
Boston, Massachusetts · daily high temperature in °C · forecasts from each model's archived runs, verified against the BOS observations
7 days out, 5 models put Boston's Thu Aug 27 high anywhere from 20° to 26°; by the final call the field had settled to a median of 28°. The day verified at 29° against the BOS observations — drizzle.
GEM landed closest, off by 0.4°. AIFS ran 3° cold.
What every model said, at every lead
Daily-high calls for Thu Aug 27 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 |
|---|---|---|---|---|---|---|---|---|
| 7d · 2026-08-20 | 23° | 20° | 26° | 26° | 21° | — | — | 20–26° |
| 6d · 2026-08-21 | 26° | 28° | 28° | 23° | 26° | 25° | — | 23–28° |
| 5d · 2026-08-22 | 26° | 28° | 28° | 25° | 28° | 28° | 26° | 25–28° |
| 4d · 2026-08-23 | 26° | 28° | 28° | 25° | 29° | 26° | 28° | 25–29° |
| 3d · 2026-08-24 | 26° | 28° | 28° | 27° | 29° | 27° | 29° | 26–29° |
| 2d · 2026-08-25 | 27° | 28° | 29° | 29° | 29° | 28° | 28° | 27–29° |
| 1d · 2026-08-26 | 27° | 28° | 28° | 30° | 28° | 27° | 29° | 27–30° |
| 0d · 2026-08-27 | 27° | 28° | 28° | 30° | 28° | 28° | 29° | 27–30° |
| actual | 29° |
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.