Which weather model is most accurate in Phoenix?
Phoenix, Arizona · daily high temperature · trailing 30 days · refreshed at most every 6 hours
Every day, The Spread archives what each major weather model predicted for Phoenix at 1-, 3-, and 7-day leads, then scores those forecasts against ERA5 reanalysis once the day has happened. This page covers the trailing 30 days (2026-07-06 to 2026-08-05), for daily high temperature.
One day out, DWD ICON has been most accurate (typical miss 1.35°F); at three days, NOAA AIGFS (AI) (1.9°F); at seven days, ECMWF AIFS (AI) (3.03°F).
The largest standing bias belongs to UKMO (UK), which has run warm by about 2.1°F at 3-day lead over this window.
The Spread's own bias-corrected blend scored a 1.03°F typical miss at one day. Its corrections come from the same window it is scored on (in-sample), so read it as a ceiling, not a promise.
The scoreboard
Typical miss (MAE) with the signed bias in parentheses — positive bias means the model ran warm. Days = scored days behind the 1-day number.
| Model | 1-day | 3-day | 7-day | Days |
|---|---|---|---|---|
| DWD ICON | 1.4° (+0.3°) | 2.4° (+0.8°) | — | 30 |
| ECMWF AIFS (AI) | 1.4° (-0.6°) | 2.0° (-0.3°) | 3.0° (-1.9°) | 30 |
| ECMWF IFS | 1.7° (+1.3°) | 2.2° (+1.7°) | 3.5° (+0.7°) | 30 |
| GEM (Canada) | 1.7° (+0.7°) | 1.9° (+0.0°) | 3.8° (+1.3°) | 30 |
| UKMO (UK) | 2.0° (-0.4°) | 3.2° (+2.1°) | — | 30 |
| NOAA AIGFS (AI) | 2.2° (-1.9°) | 1.9° (-0.9°) | 3.6° (-1.6°) | 30 |
| NOAA GFS | 2.3° (+1.7°) | 2.1° (+0.9°) | 3.4° (+0.9°) | 30 |
| NBM (US blend) | 1.3° (+0.1°) | 1.7° (+0.2°) | 2.9° (-0.8°) | 30 |
| Blended (bias-corrected) | 1.0° (-0.0°) | 1.2° (-0.0°) | 2.5° (+0.0°) | 30 |
Method, honestly
Forecasts come from each model's actual archived runs via Open-Meteo's Previous Runs API — what the model said at the time, not a reconstruction. Truth is ERA5 reanalysis daily highs. Rankings cover the models themselves; the two consensus products at the bottom of the table — NBM, which is itself a blend of models, and The Spread's own bias-corrected blend — are shown for comparison, never ranked or named "most accurate" here. The blend's corrections come from the same trailing window it is scored on (in-sample), so treat its score as a ceiling. A rolling 30-day window means these numbers move — that is the point.
Receipts — was the forecast right?
One page per settled date: what every model said as the day approached, what happened, and who was closest.
- Sun Aug 2 6 days out the models said 110–114; it hit 114. ICON led (off 0.2°); ECMWF ran 2° hot.
- Sat Aug 1 5 days out the models said 106–117; it hit 114. ICON led (off 0.2°).
- Fri Jul 31 4 days out the models said 113–116; it hit 113. AIGFS led (off 0.1°); ECMWF ran 3° hot.
- Thu Jul 30 3 days out the models said 111–114; it hit 113. AIFS led (off 0.1°); AIGFS ran 2° cold.
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The Spread — the forecast spread — is in closed beta. These verification pages are public while the rest is gated.