Was the forecast right for London on Thu Sep 17?
London, England · daily high temperature in °C · forecasts from each model's archived runs, verified against the EGLL observations
14 days out, 4 models put London's Thu Sep 17 high anywhere from 15° to 27°; by the final call, the day before, the field had settled to a median of 20°. The day verified at 21° against the EGLL observations, with 1.0 mm of precipitation.
ICON landed closest, off by 0.2°. AIGFS ran 2° cool.
What every model said, at every lead
Forecast highs for Thu Sep 17 as each model's run approached it, recorded from the last archived model run per day. NBM and The Spread's own blend are omitted because they average the other models.
| Lead | AIFS | AIGFS | ECMWF | GEM | GFS | ICON | UKMO | Range |
|---|---|---|---|---|---|---|---|---|
| 15d · 2026-09-02 | — | 15° | — | — | 25° | — | — | 15–25° |
| 14d · 2026-09-03 | 18° | 15° | 20° | — | 27° | — | — | 15–27° |
| 13d · 2026-09-04 | 17° | 19° | 16° | — | 22° | — | — | 16–22° |
| 12d · 2026-09-05 | 19° | 21° | 16° | — | 24° | — | — | 16–24° |
| 11d · 2026-09-06 | 17° | 23° | 23° | — | 18° | — | — | 17–23° |
| 10d · 2026-09-07 | 17° | 18° | 18° | — | 21° | — | — | 17–21° |
| 9d · 2026-09-08 | 17° | 16° | 18° | 14° | 20° | — | — | 14–20° |
| 8d · 2026-09-09 | 18° | 17° | 20° | 19° | 19° | — | — | 17–20° |
| 7d · 2026-09-10 | 18° | 17° | 17° | 19° | 20° | — | — | 17–20° |
| 6d · 2026-09-11 | 19° | 16° | 20° | 20° | 21° | 19° | 19° | 16–21° |
| 5d · 2026-09-12 | 19° | 18° | 20° | 20° | 18° | 20° | 20° | 18–20° |
| 4d · 2026-09-13 | 18° | 18° | 20° | 18° | 19° | 20° | 19° | 18–20° |
| 3d · 2026-09-14 | 19° | 17° | 20° | 21° | 17° | 19° | 20° | 17–21° |
| 2d · 2026-09-15 | 20° | 18° | 20° | 20° | 20° | 20° | 19° | 18–20° |
| 1d · 2026-09-16 | 20° | 18° | 20° | 19° | 20° | 21° | 20° | 18–21° |
| actual | 21° |
What one day can show
A score for one day isn't very meaningful; a useful ranking needs many days of data. See which model has been most accurate in London, or in every city The Spread scores.
Forecasts are what each model's archived runs said at the time they were recorded by The Spread; nothing is reconstructed after the fact. Truth is the EGLL observations. The actual values are the ones in hand when this day was verified, usually 2 days after the date; a correction published after that is not carried into it. Archive depth varies by city; verified days exist only for dates the archive watched arrive.