The Spread

Was the forecast right for London on Tue Sep 1?

London, England · daily high temperature in °C · forecasts from each model's archived runs, verified against the EGLL observations

10 days out, 4 models put London's Tue Sep 1 high anywhere from 18° to 21°; by the final call the field had settled to a median of 22°. The day verified at 23° against the EGLL observations — cloudy.

GFS landed closest, off by 0.1°. ECMWF ran 2° cold.

10 days out the models said 18–21; it hit 23. GFS led (off 0.1°C); ECMWF ran 2°C cold.
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 Tue Sep 1 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 London scoreboard shows them, labelled.

Lead AIFSAIGFSECMWFGEMGFSICONUKMO Range
10d · 2026-08-22 18° 21° 20° — 21° — — 18–21°
9d · 2026-08-23 20° 20° 21° 20° 20° — — 20–21°
8d · 2026-08-24 19° 21° 21° 21° 21° — — 19–21°
7d · 2026-08-25 20° 22° 20° 22° 22° — — 20–22°
6d · 2026-08-26 19° 21° 20° 20° 20° 22° 21° 19–22°
5d · 2026-08-27 21° 21° 19° 22° 22° 22° 21° 19–22°
4d · 2026-08-28 21° 21° 21° 21° 22° 22° 20° 20–22°
3d · 2026-08-29 21° 20° 21° 22° 23° 22° 22° 20–23°
2d · 2026-08-30 21° 20° 21° 22° 23° 22° 21° 20–23°
1d · 2026-08-31 21° 21° 20° 22° 23° 23° 21° 20–23°
0d · 2026-09-01 22° 21° 20° 22° 23° 22° 22° 20–23°
actual 23°

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 London — 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 EGLL observations. Archive depth varies by city; receipts exist only for dates the archive watched arrive.