Was the forecast right for Boston on Mon Aug 24?
Boston, Massachusetts · daily high temperature in °F · forecasts from each model's archived runs, verified against the BOS observations
5 days out, 7 models put Boston's Mon Aug 24 high anywhere from 78° to 85°;by the final call, the day before, the field had settled to a median of 82°. The day verified at 85° against the BOS observations — cloudy.
GEM landed closest, off by 1.4°. AIFS ran 6° cool.
What every model said, at every lead
Daily-high calls for Mon Aug 24 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 |
|---|---|---|---|---|---|---|---|---|
| 5d · 2026-08-19 | 79° | 81° | 81° | 78° | 78° | 85° | 85° | 78–85° |
| 4d · 2026-08-20 | 78° | 81° | 82° | 78° | 81° | 82° | 82° | 78–82° |
| 3d · 2026-08-21 | 78° | 80° | 79° | 78° | 80° | 83° | 84° | 78–84° |
| 2d · 2026-08-22 | 79° | 81° | 79° | 80° | 82° | 83° | 82° | 79–83° |
| 1d · 2026-08-23 | 79° | 81° | 79° | 84° | 82° | 82° | 83° | 79–84° |
| actual | 85° |
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.