Was the forecast right for San Francisco on Tue Aug 4?
San Francisco, California · daily high temperature in °C · forecasts from each model's archived runs, verified against the ECMWF IFS analysis
9 days out, 5 models put San Francisco's Tue Aug 4 high anywhere from 19° to 29°;by the final call, the day before, the field had settled to a median of 21°. The day verified at 20° against the ECMWF IFS analysis — cloudy.
ECMWF landed closest, off by 0.9°. AIGFS ran 6° warm.
What every model said, at every lead
Daily-high calls for Tue Aug 4 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 San Francisco scoreboard shows them, labelled.
| Lead | AIFS | AIGFS | ECMWF | GEM | GFS | ICON | UKMO | Range |
|---|---|---|---|---|---|---|---|---|
| 9d · 2026-07-26 | 21° | 26° | 20° | 19° | 29° | — | — | 19–29° |
| 8d · 2026-07-27 | 21° | 22° | 19° | 17° | 26° | — | — | 17–26° |
| 7d · 2026-07-28 | 21° | 24° | 17° | 18° | 27° | — | — | 17–27° |
| 6d · 2026-07-29 | 22° | 24° | 19° | 20° | 29° | 17° | 19° | 17–29° |
| 5d · 2026-07-30 | 22° | 25° | 20° | 21° | 26° | 17° | 20° | 17–26° |
| 4d · 2026-07-31 | 22° | 26° | 20° | 21° | 24° | 18° | 20° | 18–26° |
| 3d · 2026-08-01 | 21° | 26° | 20° | 23° | 26° | 18° | 20° | 18–26° |
| 2d · 2026-08-02 | 21° | 26° | 21° | 22° | 26° | 19° | 21° | 19–26° |
| 1d · 2026-08-03 | 21° | 26° | 21° | 22° | 21° | 18° | 22° | 18–26° |
| actual | 20° |
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 San Francisco — 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 ECMWF IFS analysis (temperature_2m_max). 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.