Was the forecast right for Phoenix on Sun Aug 30?
Phoenix, Arizona · daily high temperature in °F · forecasts from each model's archived runs, verified against the PHX observations
11 days out, 4 models put Phoenix's Sun Aug 30 high anywhere from 108° to 112°;by the final call, the day before, the field had settled to a median of 102°. The day verified at 106° against the PHX observations — showers.
GFS landed closest, off by 0.4°. AIFS ran 10° cool.
What every model said, at every lead
Daily-high calls for Sun Aug 30 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 |
|---|---|---|---|---|---|---|---|---|
| 11d · 2026-08-19 | 108° | 108° | 112° | — | 109° | — | — | 108–112° |
| 10d · 2026-08-20 | 107° | 106° | 113° | — | 113° | — | — | 106–113° |
| 9d · 2026-08-21 | 106° | 105° | 115° | 108° | 112° | — | — | 105–115° |
| 8d · 2026-08-22 | 105° | 105° | 111° | 110° | 112° | — | — | 105–112° |
| 7d · 2026-08-23 | 97° | 102° | 108° | 107° | 105° | — | — | 97–108° |
| 6d · 2026-08-24 | 95° | 97° | 106° | 101° | 105° | 102° | 107° | 95–107° |
| 5d · 2026-08-25 | 92° | 100° | 101° | 104° | 94° | 103° | 106° | 92–106° |
| 4d · 2026-08-26 | 96° | 100° | 105° | 104° | 104° | 102° | 104° | 96–105° |
| 3d · 2026-08-27 | 95° | 100° | 106° | 102° | 104° | 99° | 107° | 95–107° |
| 2d · 2026-08-28 | 99° | 100° | 104° | 104° | 104° | 102° | 107° | 99–107° |
| 1d · 2026-08-29 | 96° | 102° | 98° | 104° | 106° | 100° | 105° | 96–106° |
| actual | 106° |
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.