Was the forecast right for Boston on Wed Aug 5?
Boston, Massachusetts · daily high temperature in °F · forecasts from each model's archived runs, verified against the ECMWF IFS analysis
10 days out, 4 models put Boston's Wed Aug 5 high anywhere from 80° to 86°;by the final call, the day before, the field had settled to a median of 87°. The day verified at 87° against the ECMWF IFS analysis — cloudy.
ECMWF landed closest, off by 0.1°. UKMO ran 3° warm.
What every model said, at every lead
Daily-high calls for Wed Aug 5 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 |
|---|---|---|---|---|---|---|---|---|
| 10d · 2026-07-26 | 80° | 85° | 80° | — | 86° | — | — | 80–86° |
| 9d · 2026-07-27 | 84° | 91° | 84° | 83° | 72° | — | — | 72–91° |
| 8d · 2026-07-28 | 85° | 87° | 71° | 86° | 80° | — | — | 71–87° |
| 7d · 2026-07-29 | 85° | 89° | 85° | 88° | 87° | — | — | 85–89° |
| 6d · 2026-07-30 | 84° | 87° | 84° | 86° | 72° | 70° | 80° | 70–87° |
| 5d · 2026-07-31 | 84° | 87° | 82° | 84° | 75° | 80° | 82° | 75–87° |
| 4d · 2026-08-01 | 80° | 87° | 84° | 80° | 78° | 79° | 89° | 78–89° |
| 3d · 2026-08-02 | 81° | 82° | 86° | 85° | 74° | 87° | 90° | 74–90° |
| 2d · 2026-08-03 | 82° | 85° | 85° | 87° | 88° | 83° | 90° | 82–90° |
| 1d · 2026-08-04 | 84° | 87° | 87° | 90° | 88° | 87° | 90° | 84–90° |
| actual | 87° |
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). 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.