Was the forecast right for Boston on Sun Aug 16?
Boston, Massachusetts · daily high temperature in °F · forecasts from each model's archived runs, verified against the ECMWF IFS analysis
13 days out, 4 models put Boston's Sun Aug 16 high anywhere from 69° to 85°; by the final call the field had settled to a median of 80°. The ECMWF IFS analysis says the day verified at 79° — cloudy.
GFS landed closest, off by 0.2°. UKMO ran 3° hot.
What every model said, at every lead
Daily-high calls for Sun Aug 16 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 · 2026-08-01 | — | 78° | — | — | 76° | — | — | 76–78° |
| 14d · 2026-08-02 | 83° | 85° | — | — | 87° | — | — | 83–87° |
| 13d · 2026-08-03 | 85° | 75° | 70° | — | 69° | — | — | 69–85° |
| 12d · 2026-08-04 | 74° | 77° | 86° | — | 76° | — | — | 74–86° |
| 11d · 2026-08-05 | 78° | 79° | 78° | — | 70° | — | — | 70–79° |
| 10d · 2026-08-06 | 71° | 81° | 74° | — | 73° | — | — | 71–81° |
| 9d · 2026-08-07 | 76° | 78° | 90° | — | 74° | — | — | 74–90° |
| 8d · 2026-08-08 | 78° | 79° | 73° | 78° | 77° | — | — | 73–79° |
| 7d · 2026-08-09 | 76° | 78° | 78° | 80° | 76° | — | — | 76–80° |
| 6d · 2026-08-10 | 77° | 81° | 74° | 82° | 84° | 74° | — | 74–84° |
| 5d · 2026-08-11 | 80° | 81° | 85° | 82° | 83° | 74° | 82° | 74–85° |
| 4d · 2026-08-12 | 78° | 78° | 85° | 84° | 82° | 77° | 83° | 77–85° |
| 3d · 2026-08-13 | 79° | 81° | 82° | 81° | 81° | 74° | 82° | 74–82° |
| 2d · 2026-08-14 | 79° | 79° | 81° | 84° | 80° | 79° | 79° | 79–84° |
| 1d · 2026-08-15 | 79° | 79° | 82° | 83° | 80° | 78° | 80° | 78–83° |
| 0d · 2026-08-16 | 79° | 80° | 81° | 81° | 79° | 79° | 82° | 79–82° |
| actual | 79° |
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 ECMWF IFS analysis (temperature_2m_max). Archive depth varies by city; receipts exist only for dates the archive watched arrive.