Was the forecast right for Boston on Thu Sep 3?
Boston, Massachusetts · daily high temperature in °F · forecasts from each model's archived runs, verified against the BOS observations
14 days out, 4 models put Boston's Thu Sep 3 high anywhere from 73° to 79°;by the final call, the day before, the field had settled to a median of 78°. The day verified at 73° against the BOS observations, with 0.46 in of precipitation — showers.
AIFS landed closest, off by 1.2°. AIGFS ran 8° warm.
What every model said, at every lead
Daily-high calls for Thu Sep 3 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 · 2026-08-19 | — | 69° | — | — | 68° | — | — | 68–69° |
| 14d · 2026-08-20 | 74° | 73° | 78° | — | 79° | — | — | 73–79° |
| 13d · 2026-08-21 | 75° | 69° | 83° | — | 75° | — | — | 69–83° |
| 12d · 2026-08-22 | 74° | 65° | 73° | — | 70° | — | — | 65–74° |
| 11d · 2026-08-23 | 82° | 63° | 77° | — | 64° | — | — | 63–82° |
| 10d · 2026-08-24 | 77° | 74° | 79° | — | 74° | — | — | 74–79° |
| 9d · 2026-08-25 | 74° | 74° | 77° | 79° | 73° | — | — | 73–79° |
| 8d · 2026-08-26 | 78° | 82° | 74° | 69° | 68° | — | — | 68–82° |
| 7d · 2026-08-27 | 80° | 81° | 82° | 69° | 66° | — | — | 66–82° |
| 6d · 2026-08-28 | 77° | 80° | 83° | 70° | 86° | 70° | 85° | 70–86° |
| 5d · 2026-08-29 | 71° | 80° | 72° | 70° | 68° | 89° | 76° | 68–89° |
| 4d · 2026-08-30 | 79° | 79° | 81° | 79° | 75° | 77° | 68° | 68–81° |
| 3d · 2026-08-31 | 75° | 80° | 80° | 78° | 79° | 79° | 73° | 73–80° |
| 2d · 2026-09-01 | 76° | 80° | 76° | 76° | 80° | 78° | 73° | 73–80° |
| 1d · 2026-09-02 | 74° | 80° | 76° | 78° | 76° | 79° | 80° | 74–80° |
| actual | 73° |
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 BOS observations. 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.