Was the forecast right for Boston on Sat Aug 15?
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 Sat Aug 15 high anywhere from 74° to 80°; by the final call the field had settled to a median of 78°. The ECMWF IFS analysis says the day verified at 78° — cloudy.
AIGFS landed closest, off by 0.2°. GEM ran 3° hot.
What every model said, at every lead
Daily-high calls for Sat Aug 15 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 · 2026-07-31 | — | 71° | — | — | 84° | — | — | 71–84° |
| 14d · 2026-08-01 | 76° | 78° | — | — | 70° | — | — | 70–78° |
| 13d · 2026-08-02 | 80° | 80° | 75° | — | 74° | — | — | 74–80° |
| 12d · 2026-08-03 | 81° | 69° | 69° | — | 68° | — | — | 68–81° |
| 11d · 2026-08-04 | 75° | 77° | 79° | — | 78° | — | — | 75–79° |
| 10d · 2026-08-05 | 76° | 78° | 80° | — | 70° | — | — | 70–80° |
| 9d · 2026-08-06 | 78° | 79° | 74° | — | 77° | — | — | 74–79° |
| 8d · 2026-08-07 | 81° | 77° | 89° | 80° | 76° | — | — | 76–89° |
| 7d · 2026-08-08 | 76° | 81° | 78° | 77° | 81° | — | — | 76–81° |
| 6d · 2026-08-09 | 77° | 81° | 81° | 78° | 78° | 79° | — | 77–81° |
| 5d · 2026-08-10 | 79° | 82° | 81° | 79° | 72° | 78° | 82° | 72–82° |
| 4d · 2026-08-11 | 78° | 79° | 81° | 78° | 72° | 83° | 81° | 72–83° |
| 3d · 2026-08-12 | 77° | 78° | 82° | 77° | 73° | 82° | 77° | 73–82° |
| 2d · 2026-08-13 | 78° | 77° | 81° | 80° | 72° | 82° | 78° | 72–82° |
| 1d · 2026-08-14 | 78° | 78° | 80° | 77° | 80° | 81° | 80° | 77–81° |
| 0d · 2026-08-15 | 77° | 78° | 78° | 81° | 78° | 81° | 77° | 77–81° |
| actual | 78° |
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.