Was the forecast right for Boston on Thu Aug 27?

Boston, Massachusetts · daily high temperature in °F · forecasts from each model's archived runs, verified against the BOS observations

8 days out, 5 models put Boston's Thu Aug 27 high anywhere from 70° to 84°;by the final call, the day before, the field had settled to a median of 83°. The day verified at 85° against the BOS observations — drizzle.

GEM landed closest, off by 0.6°. AIFS ran 5° cool.

8 days out the models said 70–84; it hit 85. GEM led (off 0.6°F); AIFS ran 5°F cool. — The shareable card for this receipt — what this page looks like pasted into a thread.

What every model said, at every lead

Daily-high calls for Thu Aug 27 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
8d · 2026-08-19	78°	84°	81°	80°	70°	—	—	70–84°
7d · 2026-08-20	73°	69°	84°	79°	74°	—	—	69–84°
6d · 2026-08-21	79°	82°	81°	74°	82°	82°	77°	74–82°
5d · 2026-08-22	79°	82°	85°	78°	78°	83°	83°	78–85°
4d · 2026-08-23	79°	83°	82°	78°	83°	80°	84°	78–84°
3d · 2026-08-24	79°	83°	81°	84°	82°	82°	85°	79–85°
2d · 2026-08-25	80°	82°	84°	85°	82°	82°	83°	80–85°
1d · 2026-08-26	80°	83°	81°	86°	83°	82°	83°	80–86°
actual								85°

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.