Was the forecast right for Phoenix on Mon Aug 31?
Phoenix, Arizona · daily high temperature in °C · forecasts from each model's archived runs, verified against the PHX observations
12 days out, 4 models put Phoenix's Mon Aug 31 high anywhere from 40° to 42°;by the final call, the day before, the field had settled to a median of 33°. The day verified at 33° against the PHX observations, with 4.1 mm of precipitation — thunderstorms.
UKMO landed closest, off by 0.0°. GFS ran 5° warm.
What every model said, at every lead
Daily-high calls for Mon Aug 31 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 Phoenix scoreboard shows them, labelled.
| Lead | AIFS | AIGFS | ECMWF | GEM | GFS | ICON | UKMO | Range |
|---|---|---|---|---|---|---|---|---|
| 12d · 2026-08-19 | 41° | 40° | 42° | — | 41° | — | — | 40–42° |
| 11d · 2026-08-20 | 37° | 35° | 42° | — | 43° | — | — | 35–43° |
| 10d · 2026-08-21 | 40° | 39° | 45° | — | 44° | — | — | 39–45° |
| 9d · 2026-08-22 | 40° | 40° | 44° | 41° | 43° | — | — | 40–44° |
| 8d · 2026-08-23 | 37° | 39° | 41° | 40° | 41° | — | — | 37–41° |
| 7d · 2026-08-24 | 36° | 36° | 39° | 32° | 37° | — | — | 32–39° |
| 6d · 2026-08-25 | 34° | 36° | 36° | 34° | 39° | 39° | 36° | 34–39° |
| 5d · 2026-08-26 | 36° | 35° | 40° | 35° | 36° | 36° | 41° | 35–41° |
| 4d · 2026-08-27 | 36° | 36° | 34° | 36° | 38° | 39° | 41° | 34–41° |
| 3d · 2026-08-28 | 35° | 35° | 37° | 35° | 36° | 35° | 40° | 35–40° |
| 2d · 2026-08-29 | 33° | 34° | 34° | 30° | 37° | 32° | 38° | 30–38° |
| 1d · 2026-08-30 | 32° | 33° | 33° | 36° | 38° | 32° | 33° | 32–38° |
| actual | 33° |
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 Phoenix — 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 PHX 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.