Was the forecast right for London on Mon Sep 21?
London, England · daily high temperature in °F · forecasts from each model's archived runs, verified against the EGLL observations
14 days out, 4 models put London's Mon Sep 21 high anywhere from 63° to 68°;by the final call, the day before, the field had settled to a median of 70°. The day verified at 76° against the EGLL observations — partly cloudy.
GFS landed closest, off by 3.2°. GEM ran 8° cool.
What every model said, at every lead
Daily-high calls for Mon Sep 21 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 | AIFS | AIGFS | ECMWF | GEM | GFS | ICON | UKMO | Range |
|---|---|---|---|---|---|---|---|---|
| 15d · 2026-09-06 | — | 67° | — | — | 76° | — | — | 67–76° |
| 14d · 2026-09-07 | 68° | 63° | 67° | — | 66° | — | — | 63–68° |
| 13d · 2026-09-08 | 66° | 69° | 72° | — | 75° | — | — | 66–75° |
| 12d · 2026-09-09 | 72° | 75° | 64° | — | 70° | — | — | 64–75° |
| 11d · 2026-09-10 | 70° | 67° | 70° | — | 65° | — | — | 65–70° |
| 10d · 2026-09-11 | 70° | 60° | 66° | — | 76° | — | — | 60–76° |
| 9d · 2026-09-12 | 70° | 69° | 70° | 77° | 64° | — | — | 64–77° |
| 8d · 2026-09-13 | 73° | 73° | 66° | 74° | 77° | — | — | 66–77° |
| 7d · 2026-09-14 | 72° | 74° | 73° | 73° | 79° | — | — | 72–79° |
| 6d · 2026-09-15 | 72° | 69° | 73° | 73° | 75° | 78° | 73° | 69–78° |
| 5d · 2026-09-16 | 71° | 73° | 65° | 71° | 75° | 72° | 72° | 65–75° |
| 4d · 2026-09-17 | 72° | 70° | 69° | 74° | 76° | 74° | 74° | 69–76° |
| 3d · 2026-09-18 | 72° | 67° | 72° | 72° | 75° | 68° | 71° | 67–75° |
| 2d · 2026-09-19 | 71° | 67° | 72° | 68° | 74° | 71° | 71° | 67–74° |
| 1d · 2026-09-20 | 71° | 69° | 68° | 68° | 73° | 71° | 70° | 68–73° |
| actual | 76° |
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.