Was the forecast right for Phoenix on Tue Sep 1?
Phoenix, Arizona · daily high temperature in °F · forecasts from each model's archived runs, verified against the PHX observations
13 days out, 4 models put Phoenix's Tue Sep 1 high anywhere from 102° to 104°;by the final call, the day before, the field had settled to a median of 99°. The day verified at 101° against the PHX observations — drizzle.
GFS landed closest, off by 0.0°. ECMWF ran 7° cool.
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 Phoenix scoreboard shows them, labelled.
| Lead | AIFS | AIGFS | ECMWF | GEM | GFS | ICON | UKMO | Range |
|---|---|---|---|---|---|---|---|---|
| 13d · 2026-08-19 | 103° | 102° | 103° | — | 104° | — | — | 102–104° |
| 12d · 2026-08-20 | 100° | 94° | 106° | — | 107° | — | — | 94–107° |
| 11d · 2026-08-21 | 103° | 102° | 108° | — | 107° | — | — | 102–108° |
| 10d · 2026-08-22 | 104° | 106° | 111° | — | 105° | — | — | 104–111° |
| 9d · 2026-08-23 | 102° | 101° | 107° | 103° | 110° | — | — | 101–110° |
| 8d · 2026-08-24 | 102° | 97° | 100° | 98° | 100° | — | — | 97–102° |
| 7d · 2026-08-25 | 100° | 100° | 104° | 100° | 103° | — | — | 100–104° |
| 6d · 2026-08-26 | 102° | 99° | 105° | 100° | 98° | 98° | 104° | 98–105° |
| 5d · 2026-08-27 | 101° | 100° | 96° | 101° | 101° | 103° | 104° | 96–104° |
| 4d · 2026-08-28 | 98° | 99° | 100° | 97° | 100° | 99° | 105° | 97–105° |
| 3d · 2026-08-29 | 98° | 100° | 98° | 97° | 100° | 98° | 103° | 97–103° |
| 2d · 2026-08-30 | 98° | 99° | 100° | 99° | 100° | 97° | 99° | 97–100° |
| 1d · 2026-08-31 | 96° | 99° | 94° | 101° | 101° | 99° | 97° | 94–101° |
| actual | 101° |
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.