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Which weather model is most accurate in Boston?

Forecast Highs Lows Rain Model accuracy

Boston, Massachusetts · daily high temperature in °F · trailing 30 days, through Fri Oct 16

Every day, The Spread archives what each major weather model predicted for Boston at 1-, 3-, and 7-day leads, then scores those forecasts against the BOS observations once the day has happened. This page covers the trailing 30 days (2026-09-17 to 2026-10-16), 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 cool by about 2.28°F at 3-day lead over this window.

Boston's full forecast, every model day by day, with the record on this page beside it. Request an invite; it's free during the beta.

The scoreboard

Typical miss (MAE) in °F with the bias in parentheses. Bias is the mean signed error of the predicted daily high — positive means the model ran warm. A model's high is the warmest of its hourly values and the station's is the warmest it got at any moment, so a model's high reads a little cool, and its low a little warm, even on a day it gets every hour right. ECMWF IFS gives a value only every 3 hours (every 6 past day 6), and ECMWF AIFS (AI) and NOAA AIGFS (AI) only every 6, with the hours between filled in, so their highs read cooler still and their lows warmer. In the forecasts scored here GFS also steps to every 3 hours from day 5, ICON and GEM from day 4, and UKMO from day 3, every 6 by day 6. Days = scored days behind the 1-day number.

Model 1-day 3-day 7-day Days
GEM (Canada) 1.5° (+1.0°) 2.6° (-0.9°) 5.4° (-1.9°) 29
DWD ICON 1.6° (-0.4°) 2.1° (-0.3°) — 29
NOAA AIGFS (AI) 1.9° (-0.9°) 3.0° (-1.2°) 4.7° (-0.7°) 29
ECMWF AIFS (AI) 2.1° (-1.5°) 2.2° (-1.6°) 5.3° (-1.5°) 29
ECMWF IFS 2.2° (-1.4°) 3.2° (-1.1°) 4.9° (-3.0°) 29
UKMO (UK) 2.2° (-0.1°) 3.4° (-0.7°) — 29
NOAA GFS 2.6° (-2.1°) 3.1° (-2.3°) 5.4° (-4.4°) 29

Method, honestly

The Spread's Boston point is the Logan station (BOS), 2.5 mi from downtown, used for both forecasts and verifications. Each forecast is the last one The Spread archived on the day it was made, the forecast the model was showing at the time, not a reconstruction. A day the station did not report is left out. Truth is the thermometer at Logan (BOS) — 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; consensus products such as the NBM, itself a blend of models, are not scored here. 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.

  • Fri Oct 16 14 days out the models said 63–67; it hit 69. ECMWF led (off 0.0°F); GFS ran 4°F cool.
  • Thu Oct 15 14 days out the models said 52–75; it hit 62. GEM led (off 0.2°F).
  • Wed Oct 14 14 days out the models said 57–69; it hit 77. AIGFS led (off 0.5°F); AIFS ran 5°F cool.
  • Tue Oct 13 14 days out the models said 55–70; it hit 62. ICON led (off 0.2°F); UKMO ran 3°F warm.
  • Mon Oct 12 14 days out the models said 56–65; it hit 71. GEM led (off 1.4°F); AIFS ran 5°F cool.
  • Sun Oct 11 14 days out the models said 54–60; it hit 60. ECMWF led (off 0.4°F); UKMO ran 4°F warm.
  • Sat Oct 10 14 days out the models said 52–68; it hit 63. ICON led (off 0.4°F); GEM ran 3°F warm.
  • Fri Oct 9 14 days out the models said 60–64; it hit 69. GEM led (off 0.1°F); UKMO ran 3°F cool.
  • Thu Oct 8 14 days out the models said 54–65; it hit 73. ICON led (off 0.1°F); ECMWF ran 2°F cool.
  • Wed Oct 7 14 days out the models said 57–68; it hit 66. UKMO led (off 0.2°F); ECMWF ran 3°F cool.
  • Tue Oct 6 13 days out the models said 58–70; it hit 63. ICON led (off 2.1°F); UKMO ran 5°F cool.
  • Mon Oct 5 14 days out the models said 62–74; it hit 71. GEM led (off 0.6°F); UKMO ran 4°F cool.
  • Sun Oct 4 14 days out the models said 59–73; it hit 63. ICON led (off 0.4°F).
  • Sat Oct 3 14 days out the models said 57–74; it hit 67. ICON led (off 0.4°F); UKMO ran 3°F warm.
  • Fri Oct 2 14 days out the models said 66–74; it hit 87. GEM led (off 0.9°F); GFS ran 7°F cool.
  • Thu Oct 1 14 days out the models said 62–69; it hit 79. UKMO led (off 0.0°F); GFS ran 6°F cool.
  • Wed Sep 30 14 days out the models said 59–74; it hit 66. AIFS led (off 0.6°F); GEM ran 6°F warm.
  • Tue Sep 29 14 days out the models said 66–78; it hit 66. UKMO led (off 0.6°F).
  • Mon Sep 28 14 days out the models said 65–77; it hit 58. GFS led (off 0.3°F); ICON ran 4°F warm.
  • Sun Sep 27 14 days out the models said 65–72; it hit 60. GFS led (off 0.6°F); AIFS ran 2°F warm.
  • Sat Sep 26 14 days out the models said 64–72; it hit 61. ICON led (off 0.5°F); GFS ran 3°F cool.
  • Fri Sep 25 14 days out the models said 60–75; it hit 64. ICON led (off 0.1°F); GFS ran 4°F cool.
  • Thu Sep 24 14 days out the models said 59–70; it hit 65. GEM led (off 0.6°F); GFS ran 5°F cool.
  • Wed Sep 23 14 days out the models said 57–77; it hit 64. GEM led (off 0.3°F); GFS ran 4°F cool.
  • Tue Sep 22 14 days out the models said 65–67; it hit 63. ICON led (off 0.5°F); AIGFS ran 4°F cool.
  • Mon Sep 21 14 days out the models said 64–73; it hit 65. UKMO led (off 0.2°F); ICON ran 2°F warm.
  • Sun Sep 20 14 days out the models said 59–70; it hit 63. ECMWF led (off 0.5°F); AIGFS ran 5°F cool.
  • Sat Sep 19 14 days out the models said 64–75; it hit 62. ECMWF led (off 0.1°F); UKMO ran 3°F warm.
  • Fri Sep 18 14 days out the models said 65–80; it hit 80. AIGFS led (off 0.1°F); AIFS ran 3°F cool.
  • Thu Sep 17 14 days out the models said 67–79; it hit 76. ICON led (off 0.8°F); GEM ran 6°F warm.
  • Wed Sep 16 14 days out the models said 66–79; it hit 80. UKMO led (off 0.8°F); ECMWF ran 6°F cool.
  • Tue Sep 15 14 days out the models said 59–91; it hit 66. AIFS led (off 0.3°F); GFS ran 3°F cool.
  • Mon Sep 14 14 days out the models said 72–79; it hit 74. UKMO led (off 0.3°F); ECMWF ran 3°F cool.
  • Sun Sep 13 14 days out the models said 66–78; it hit 70. ICON led (off 0.2°F); GFS ran 4°F cool.
  • Sat Sep 12 14 days out the models said 60–88; it hit 71. GFS led (off 0.3°F); AIGFS ran 5°F warm.
  • Fri Sep 11 14 days out the models said 72–98; it hit 79. GEM led (off 0.7°F); AIFS ran 3°F cool.
  • Thu Sep 10 14 days out the models said 70–87; it hit 87. GEM led (off 0.3°F); ECMWF ran 3°F cool.
  • Wed Sep 9 14 days out the models said 65–89; it hit 76. AIFS led (off 0.5°F); GEM ran 9°F warm.
  • Tue Sep 8 14 days out the models said 69–79; it hit 81. GEM led (off 0.7°F); UKMO ran 5°F cool.
  • Mon Sep 7 14 days out the models said 73–82; it hit 82. GEM led (off 0.0°F); GFS ran 5°F cool.
  • Sun Sep 6 14 days out the models said 67–78; it hit 68. GFS led (off 0.2°F); GEM ran 4°F warm.
  • Sat Sep 5 14 days out the models said 61–78; it hit 73. GEM led (off 0.7°F); ECMWF ran 4°F cool.
  • Fri Sep 4 14 days out the models said 67–82; it hit 85. ICON led (off 1.5°F); AIFS ran 5°F cool.
  • Thu Sep 3 14 days out the models said 73–79; it hit 73. AIFS led (off 1.2°F); AIGFS ran 8°F warm.
  • Wed Sep 2 14 days out the models said 64–75; it hit 72. UKMO led (off 0.0°F); GEM ran 2°F warm.
  • Tue Sep 1 13 days out the models said 70–87; it hit 69. ICON led (off 0.1°F); UKMO ran 4°F warm.
  • Mon Aug 31 12 days out the models said 80–83; it hit 73. ICON led (off 0.2°F); AIGFS ran 6°F warm.
  • Sun Aug 30 11 days out the models said 74–78; it hit 86. ICON led (off 0.0°F); AIFS ran 4°F cool.
  • Sat Aug 29 10 days out the models said 69–80; it hit 74. GFS led (off 1.1°F); UKMO ran 6°F warm.
  • Fri Aug 28 9 days out the models said 68–83; it hit 83. GEM led (off 0.1°F); ECMWF ran 4°F cool.
  • Thu Aug 27 8 days out the models said 70–84; it hit 85. GEM led (off 0.6°F); AIFS ran 5°F cool.
  • Wed Aug 26 7 days out the models said 77–83; it hit 78. ICON led (off 0.8°F); ECMWF ran 3°F warm.
  • Tue Aug 25 6 days out the models said 75–81; it hit 81. ICON led (off 1.1°F); AIFS ran 4°F cool.
  • Mon Aug 24 5 days out the models said 78–85; it hit 85. GEM led (off 1.4°F); AIFS ran 6°F cool.
  • Sun Aug 23 4 days out the models said 70–85; it hit 71. GEM led (off 1.3°F); UKMO ran 5°F warm.
  • Mon Aug 17 14 days out the models said 73–78; it hit 76. ECMWF led (off 0.2°F); GFS ran 6°F cool.
  • Sun Aug 16 14 days out the models said 72–84; it hit 79. AIFS led (off 0.5°F); GEM ran 4°F warm.
  • Sat Aug 15 14 days out the models said 68–82; it hit 78. AIGFS led (off 0.1°F); ICON ran 3°F warm.
  • Fri Aug 14 14 days out the models said 70–80; it hit 82. ECMWF led (off 0.3°F); GFS ran 2°F warm.
  • Thu Aug 13 14 days out the models said 71–84; it hit 83. GFS led (off 0.5°F); GEM ran 4°F warm.
  • Wed Aug 12 14 days out the models said 72–79; it hit 85. AIGFS led (off 0.2°F); GEM ran 3°F warm.
  • Tue Aug 11 14 days out the models said 79–87; it hit 87. UKMO led (off 0.4°F); AIGFS ran 3°F warm.
  • Mon Aug 10 14 days out the models said 78–88; it hit 85. AIFS led (off 0.6°F); UKMO ran 7°F warm.
  • Sun Aug 9 14 days out the models said 77–91; it hit 91. ICON led (off 0.1°F); AIFS ran 3°F cool.
  • Sat Aug 8 13 days out the models said 75–92; it hit 93. GFS led (off 1.6°F); AIFS ran 7°F cool.
  • Fri Aug 7 12 days out the models said 75–92; it hit 96. GFS led (off 1.3°F); AIFS ran 8°F cool.
  • Thu Aug 6 11 days out the models said 76–89; it hit 90. ICON led (off 0.3°F); AIFS ran 4°F cool.
  • Wed Aug 5 10 days out the models said 80–86; it hit 87. ECMWF led (off 0.1°F); UKMO ran 3°F warm.
  • Tue Aug 4 9 days out the models said 69–86; it hit 85. ECMWF led (off 0.9°F); GFS ran 4°F cool.
  • Mon Aug 3 8 days out the models said 77–84; it hit 76. AIFS led (off 1.3°F); UKMO ran 4°F warm.
  • Sun Aug 2 7 days out the models said 78–86; it hit 84. ECMWF led (off 0.1°F); UKMO ran 4°F warm.
  • Sat Aug 1 6 days out the models said 71–87; it hit 86. ICON led (off 0.3°F); AIFS ran 4°F cool.
  • Fri Jul 31 5 days out the models said 68–79; it hit 76. AIFS led (off 0.1°F); GFS ran 5°F warm.
  • Thu Jul 30 4 days out the models said 67–75; it hit 73. ECMWF led (off 4.0°F); AIGFS ran 8°F cool.

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