Was the forecast right for Boston on Thu Aug 13?
Boston, Massachusetts · daily high temperature in °F · forecasts from each model's archived runs, verified against ERA5
13 days out, 4 models put Boston's Thu Aug 13 high anywhere from 68° to 85°; by the final call the field had settled to a median of 83°. ERA5 says the day verified at 83° with 0.06 in of precipitation — drizzle.
ICON landed closest, off by 0.1°. ECMWF ran 2° cold.
What every model said, at every lead
Daily-high calls for Thu Aug 13 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 · 2026-07-29 | — | 84° | — | — | 67° | — | — | 67–84° |
| 14d · 2026-07-30 | 84° | 85° | — | — | 71° | — | — | 71–85° |
| 13d · 2026-07-31 | 81° | 77° | 85° | — | 68° | — | — | 68–85° |
| 12d · 2026-08-01 | 77° | 76° | 79° | — | 71° | — | — | 71–79° |
| 11d · 2026-08-02 | 78° | 79° | 93° | — | 71° | — | — | 71–93° |
| 10d · 2026-08-03 | 80° | 84° | 80° | — | 70° | — | — | 70–84° |
| 9d · 2026-08-04 | 81° | 86° | 78° | — | 78° | — | — | 78–86° |
| 8d · 2026-08-05 | 83° | 80° | 88° | 83° | 78° | — | — | 78–88° |
| 7d · 2026-08-06 | 81° | 87° | 87° | 84° | 82° | — | — | 81–87° |
| 6d · 2026-08-07 | 81° | 77° | 87° | 78° | 79° | 82° | — | 77–87° |
| 5d · 2026-08-08 | 83° | 86° | 80° | 85° | 86° | 86° | 80° | 80–86° |
| 4d · 2026-08-09 | 82° | 88° | 82° | 76° | 84° | 89° | 80° | 76–89° |
| 3d · 2026-08-10 | 82° | 87° | 90° | 83° | 87° | 89° | 86° | 82–90° |
| 2d · 2026-08-11 | 81° | 85° | 87° | 80° | 83° | 88° | 86° | 80–88° |
| 1d · 2026-08-12 | 80° | 82° | 87° | 88° | 77° | 86° | 84° | 77–88° |
| 0d · 2026-08-13 | 81° | 82° | 81° | 84° | 85° | 83° | 83° | 81–85° |
| actual | 83° |
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.