Which weather model is most accurate in Washington?

Outlook Model accuracy

Washington, District of Columbia · daily high temperature in °C · trailing 30 days · refreshed at most every 6 hours

Every day, The Spread archives what each major weather model predicted for Washington at 1-, 3-, and 7-day leads, then scores those forecasts against the DCA observations once the day has happened. This page covers the trailing 30 days (2026-08-04 to 2026-09-02), for daily high temperature.

One day out, too close to call; at three days, too close to call; at seven days, too close to call.

The largest standing bias belongs to NOAA GFS, which has run warm by about 1.1°C at 1-day lead over this window.

The Spread's own bias-corrected blend scored a 0.77°C 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) in °C 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
UKMO (UK)	0.8° (+0.2°)	1.5° (+0.7°)	—	30
GEM (Canada)	0.9° (-0.2°)	2.0° (-1.1°)	2.0° (-0.4°)	30
NOAA AIGFS (AI)	1.1° (-0.5°)	1.3° (-0.5°)	1.9° (-0.7°)	30
DWD ICON	1.1° (-0.5°)	1.5° (+0.4°)	—	30
ECMWF AIFS (AI)	1.1° (-0.8°)	1.2° (-0.6°)	1.8° (-0.4°)	30
ECMWF IFS	1.4° (+0.1°)	1.9° (-0.0°)	2.3° (+0.0°)	30
NOAA GFS	1.5° (+1.1°)	1.8° (+1.0°)	2.6° (+1.8°)	30
NBM (US blend)	1.0° (-0.6°)	1.5° (-0.5°)	1.6° (-0.9°)	30
Blended (bias-corrected)	0.8° (-0.0°)	1.3° (+0.0°)	1.4° (-0.0°)	30

Method, honestly

The Spread's Washington point is the Washington National station (DCA), 5.9 km from downtown, used for both forecasts and verifications. 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 DCA observations — the station's own daily highs, a thermometer rather than a grid, and no correction applies: the thermometer is the truth outright. 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.

Tue Sep 1 12 days out the models said 24–37; it hit 37. GFS led (off 0.5°C); AIGFS ran 3°C cold.
Mon Aug 31 11 days out the models said 24–34; it hit 31. ICON led (off 0.4°C); GFS ran 4°C hot.
Sun Aug 30 10 days out the models said 24–35; it hit 32. UKMO led (off 0.1°C); GFS ran 3°C hot.
Sat Aug 29 9 days out the models said 28–33; it hit 29. ICON led (off 0.1°C); AIGFS ran 2°C cold.
Fri Aug 28 8 days out the models said 29–32; it hit 32. GFS led (off 0.1°C); AIFS ran 3°C cold.
Thu Aug 27 7 days out the models said 26–31; it hit 31. GEM led (off 0.0°C); GFS ran 2°C hot.
Wed Aug 26 6 days out the models said 28–31; it hit 30. ICON led (off 0.1°C); GFS ran 2°C hot.
Tue Aug 25 5 days out the models said 26–30; it hit 29. GEM led (off 0.5°C); UKMO ran 1°C cold.
Mon Aug 24 4 days out the models said 25–29; it hit 29. AIGFS led (off 0.9°C); ECMWF ran 2°C cold.
Sun Aug 23 3 days out the models said 27–30; it hit 31. GFS led (off 0.6°C); ECMWF ran 2°C cold.
Mon Aug 17 13 days out the models said 26–31; it hit 32. ICON led (off 0.1°C); GEM ran 2°C hot.
Sun Aug 16 13 days out the models said 27–32; it hit 27. UKMO led (off 0.6°C); AIFS ran 2°C cold.
Sat Aug 15 13 days out the models said 28–39; it hit 31. AIFS led (off 0.2°C); GEM ran 2°C hot.
Fri Aug 14 13 days out the models said 24–33; it hit 26. ICON led (off 2.1°C); UKMO ran 5°C hot.
Thu Aug 13 13 days out the models said 29–38; it hit 32. UKMO led (off 0.1°C); GEM ran 3°C hot.
Wed Aug 12 13 days out the models said 26–33; it hit 31. ICON led (off 0.3°C); GEM ran 4°C hot.
Tue Aug 11 13 days out the models said 30–32; it hit 31. AIGFS led (off 0.3°C); GEM ran 2°C hot.
Mon Aug 10 13 days out the models said 32–40; it hit 32. ICON led (off 1.9°C); GEM ran 5°C hot.
Sun Aug 9 13 days out the models said 26–33; it hit 33. ICON led (off 0.7°C); GEM ran 3°C hot.
Sat Aug 8 12 days out the models said 28–35; it hit 32. UKMO led (off 0.8°C); GFS ran 3°C hot.
Fri Aug 7 11 days out the models said 32–38; it hit 32. ICON led (off 0.9°C); GEM ran 4°C hot.
Thu Aug 6 10 days out the models said 31–37; it hit 34. ICON led (off 0.2°C); GEM ran 2°C hot.
Wed Aug 5 9 days out the models said 29–35; it hit 30. ICON led (off 0.1°C); GEM ran 2°C hot.
Tue Aug 4 8 days out the models said 29–32; it hit 31. ICON led (off 0.1°C); GEM ran 2°C hot.
Mon Aug 3 7 days out the models said 28–32; it hit 31. AIFS led (off 0.1°C); AIGFS ran 2°C cold.
Sun Aug 2 6 days out the models said 26–32; it hit 28. ICON led (off 0.7°C); GFS ran 4°C hot.
Sat Aug 1 5 days out the models said 30–33; it hit 32. ECMWF led (off 0.1°C); ICON ran 2°C cold.
Fri Jul 31 4 days out the models said 29–31; it hit 32. GFS led (off 0.1°C); GEM ran 2°C hot.
Thu Jul 30 3 days out the models said 27–30; it hit 30. GFS led (off 0.1°C); GEM ran 2°C hot.

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The Spread — the forecast spread — is in closed beta. These verification pages are public while the rest is gated.