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
14 days out, 4 models put Boston's Sun Aug 16 high anywhere from 72° to 84°;by the final call, the day before, the field had settled to a median of 81°. The day verified at 79° against the ECMWF IFS analysis — cloudy.
AIFS landed closest, off by 0.5°. GEM ran 4° warm.
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 | — | 79° | — | — | 70° | — | — | 70–79° |
| 14d · 2026-08-02 | 81° | 84° | 73° | — | 72° | — | — | 72–84° |
| 13d · 2026-08-03 | 74° | 78° | 76° | — | 72° | — | — | 72–78° |
| 12d · 2026-08-04 | 76° | 69° | 77° | — | 70° | — | — | 69–77° |
| 11d · 2026-08-05 | 77° | 77° | 80° | — | 78° | — | — | 77–80° |
| 10d · 2026-08-06 | 74° | 79° | 79° | — | 80° | — | — | 74–80° |
| 9d · 2026-08-07 | 76° | 78° | 81° | 77° | 72° | — | — | 72–81° |
| 8d · 2026-08-08 | 79° | 81° | 71° | 77° | 74° | — | — | 71–81° |
| 7d · 2026-08-09 | 78° | 78° | 74° | 76° | 72° | — | — | 72–78° |
| 6d · 2026-08-10 | 79° | 76° | 82° | 80° | 81° | 68° | 78° | 68–82° |
| 5d · 2026-08-11 | 78° | 80° | 83° | 81° | 81° | 76° | 80° | 76–83° |
| 4d · 2026-08-12 | 79° | 80° | 86° | 83° | 81° | 75° | 78° | 75–86° |
| 3d · 2026-08-13 | 79° | 80° | 80° | 85° | 82° | 83° | 74° | 74–85° |
| 2d · 2026-08-14 | 79° | 80° | 82° | 83° | 79° | 78° | 79° | 78–83° |
| 1d · 2026-08-15 | 79° | 80° | 82° | 83° | 81° | 78° | 81° | 78–83° |
| 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). 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.