Was the forecast right for Boston on Sun Aug 2?
Boston, Massachusetts · daily high temperature · forecasts from each model's archived runs, verified against ERA5
6 days out, 6 models put Boston's Sun Aug 2 high anywhere from 68° to 81°; by the final call the field had settled to a median of 86°. ERA5 says the day verified at 84° with 0.04 in of precipitation — drizzle.
ECMWF landed closest, off by 0.5°. GEM ran 4° hot.
What every model said, at every lead
Daily-high calls for Sun Aug 2 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 |
|---|---|---|---|---|---|---|---|---|
| 6d · 2026-07-27 | 81° | 81° | 77° | 81° | 68° | 74° | — | 68–81° |
| 5d · 2026-07-28 | 80° | 88° | 84° | 81° | 74° | 81° | 85° | 74–88° |
| 4d · 2026-07-29 | 79° | 84° | 81° | 80° | 81° | 85° | 83° | 79–85° |
| 3d · 2026-07-30 | 80° | 85° | 83° | 80° | 81° | 84° | 87° | 80–87° |
| 2d · 2026-07-31 | 80° | 84° | 83° | 85° | 84° | 85° | 86° | 80–86° |
| 1d · 2026-08-01 | 81° | 86° | 84° | 87° | 85° | 85° | 87° | 81–87° |
| 0d · 2026-08-02 | 82° | 86° | 84° | 88° | 87° | 85° | 87° | 82–88° |
| actual | 84° |
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 ERA5 reanalysis (temperature_2m_max). Archive depth varies by city; receipts exist only for dates the archive watched arrive.