Which weather model is most accurate in Atlanta?
Atlanta, Georgia · daily high temperature · trailing 30 days · refreshed at most every 6 hours
Every day, The Spread archives what each major weather model predicted for Atlanta 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, ECMWF IFS has been most accurate (typical miss 1.59°F); at three days, ECMWF IFS (2.49°F); at seven days, ECMWF IFS (2.72°F).
The largest standing bias belongs to GEM (Canada), which has run cool by about 3.59°F at 3-day lead over this window.
The Spread's own bias-corrected blend scored a 1.14°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 |
|---|---|---|---|---|
| ECMWF IFS | 1.6° (-0.6°) | 2.5° (-1.7°) | 2.7° (-0.7°) | 30 |
| NOAA GFS | 1.8° (+0.9°) | 4.3° (+3.1°) | 6.9° (+6.1°) | 30 |
| NOAA AIGFS (AI) | 2.1° (-1.6°) | 2.9° (-2.6°) | 3.8° (-3.1°) | 30 |
| DWD ICON | 2.2° (-0.2°) | 2.7° (+0.5°) | — | 30 |
| UKMO (UK) | 2.4° (+1.6°) | 2.6° (+1.4°) | — | 30 |
| ECMWF AIFS (AI) | 2.6° (-2.5°) | 2.7° (-2.6°) | 2.7° (-1.7°) | 30 |
| GEM (Canada) | 3.1° (-2.8°) | 3.9° (-3.6°) | 3.4° (-2.5°) | 30 |
| NBM (US blend) | 1.8° (-1.5°) | 1.9° (-1.5°) | 1.8° (-0.7°) | 30 |
| Blended (bias-corrected) | 1.1° (+0.0°) | 1.4° (-0.0°) | 1.8° (+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 77–91; it hit 88. GFS led (off 0.5°); ECMWF ran 5° cold.
- Sat Aug 1 5 days out the models said 78–95; it hit 87. UKMO led (off 0.6°); AIFS ran 6° cold.
- Fri Jul 31 4 days out the models said 87–92; it hit 90. ECMWF led (off 0.4°); GEM ran 3° cold.
- Thu Jul 30 3 days out the models said 84–94; it hit 90. ECMWF led (off 0.3°); GEM ran 5° cold.
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