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CastCheck methodology v0.2 · data through 2026-08-30

Boston Logan · GraphCast (GFS init) · lead day 1

KBOS · graphcast_gfs · lead 1

Target day = initialization date + 1 day. This page is a permanent link: the numbers change as history accumulates, the address and the methodology version do not.

Scores use the latest model version segment, GRAP_v100, starting 2026-08-28 — days before that ran a different version of the model and are excluded rather than silently pooled. Of the scored days, 1 carry a QC flag on the observation.

JSON for this page CSV of the daily errors Cite this page

Every number for this combination

All four windows × both initializations × both interpolations × both variables. Errors are computed in °C and shown in °F; CI is a 95 % moving-block bootstrap interval. MAE debiased and skill, debiased remove the constant offset of the window first, so a station that the model always reads a degree too warm is not scored as if it had no skill — compare the two skill columns to see how much of the error is a fixed offset. n QC next to n counts days whose observation carries a QC flag.

VariableInitMethod Windown MAE °F MAE debiased Bias °F RMSE °F ±1 °F±2 °F±3 °F Skill Skill, debiased Period
tmax00Zbilinear30d1 1 QC5.34 [5.34, 5.34]0.00-5.34 [-5.34, -5.34]5.34 [5.34, 5.34]0% [0%, 0%]0%0%+0.51—2026-08-30 → 2026-08-30
tmax00Zbilinear90d1 1 QC5.34 [5.34, 5.34]0.00-5.34 [-5.34, -5.34]5.34 [5.34, 5.34]0% [0%, 0%]0%0%+0.51—2026-08-30 → 2026-08-30
tmax00Zbilinear365d1 1 QC5.34 [5.34, 5.34]0.00-5.34 [-5.34, -5.34]5.34 [5.34, 5.34]0% [0%, 0%]0%0%+0.51—2026-08-30 → 2026-08-30
tmax00Zbilinearall1 1 QC5.34 [5.34, 5.34]0.00-5.34 [-5.34, -5.34]5.34 [5.34, 5.34]0% [0%, 0%]0%0%+0.51—2026-08-30 → 2026-08-30
tmax00Znearest30d1 1 QC5.23 [5.23, 5.23]0.00-5.23 [-5.23, -5.23]5.23 [5.23, 5.23]0% [0%, 0%]0%0%+0.52—2026-08-30 → 2026-08-30
tmax00Znearest90d1 1 QC5.23 [5.23, 5.23]0.00-5.23 [-5.23, -5.23]5.23 [5.23, 5.23]0% [0%, 0%]0%0%+0.52—2026-08-30 → 2026-08-30
tmax00Znearest365d1 1 QC5.23 [5.23, 5.23]0.00-5.23 [-5.23, -5.23]5.23 [5.23, 5.23]0% [0%, 0%]0%0%+0.52—2026-08-30 → 2026-08-30
tmax00Znearestall1 1 QC5.23 [5.23, 5.23]0.00-5.23 [-5.23, -5.23]5.23 [5.23, 5.23]0% [0%, 0%]0%0%+0.52—2026-08-30 → 2026-08-30
tmax12Zbilinear30d2 1 QC4.08 [2.48, 5.69]1.60-4.08 [-5.69, -2.48]4.39 [2.48, 5.69]0% [0%, 0%]0%50%+0.48—2026-08-29 → 2026-08-30
tmax12Zbilinear90d2 1 QC4.08 [2.48, 5.69]1.60-4.08 [-5.69, -2.48]4.39 [2.48, 5.69]0% [0%, 0%]0%50%+0.48—2026-08-29 → 2026-08-30
tmax12Zbilinear365d2 1 QC4.08 [2.48, 5.69]1.60-4.08 [-5.69, -2.48]4.39 [2.48, 5.69]0% [0%, 0%]0%50%+0.48—2026-08-29 → 2026-08-30
tmax12Zbilinearall2 1 QC4.08 [2.48, 5.69]1.60-4.08 [-5.69, -2.48]4.39 [2.48, 5.69]0% [0%, 0%]0%50%+0.48—2026-08-29 → 2026-08-30
tmax12Znearest30d2 1 QC4.11 [2.58, 5.64]1.53-4.11 [-5.64, -2.58]4.39 [2.58, 5.64]0% [0%, 0%]0%50%+0.49—2026-08-29 → 2026-08-30
tmax12Znearest90d2 1 QC4.11 [2.58, 5.64]1.53-4.11 [-5.64, -2.58]4.39 [2.58, 5.64]0% [0%, 0%]0%50%+0.49—2026-08-29 → 2026-08-30
tmax12Znearest365d2 1 QC4.11 [2.58, 5.64]1.53-4.11 [-5.64, -2.58]4.39 [2.58, 5.64]0% [0%, 0%]0%50%+0.49—2026-08-29 → 2026-08-30
tmax12Znearestall2 1 QC4.11 [2.58, 5.64]1.53-4.11 [-5.64, -2.58]4.39 [2.58, 5.64]0% [0%, 0%]0%50%+0.49—2026-08-29 → 2026-08-30
tmin00Zbilinear30d1 1 QC4.45 [4.45, 4.45]0.00-4.45 [-4.45, -4.45]4.45 [4.45, 4.45]0% [0%, 0%]0%0%-1.22—2026-08-30 → 2026-08-30
tmin00Zbilinear90d1 1 QC4.45 [4.45, 4.45]0.00-4.45 [-4.45, -4.45]4.45 [4.45, 4.45]0% [0%, 0%]0%0%-1.22—2026-08-30 → 2026-08-30
tmin00Zbilinear365d1 1 QC4.45 [4.45, 4.45]0.00-4.45 [-4.45, -4.45]4.45 [4.45, 4.45]0% [0%, 0%]0%0%-1.22—2026-08-30 → 2026-08-30
tmin00Zbilinearall1 1 QC4.45 [4.45, 4.45]0.00-4.45 [-4.45, -4.45]4.45 [4.45, 4.45]0% [0%, 0%]0%0%-1.22—2026-08-30 → 2026-08-30
tmin00Znearest30d1 1 QC3.90 [3.90, 3.90]0.00-3.90 [-3.90, -3.90]3.90 [3.90, 3.90]0% [0%, 0%]0%0%-0.95—2026-08-30 → 2026-08-30
tmin00Znearest90d1 1 QC3.90 [3.90, 3.90]0.00-3.90 [-3.90, -3.90]3.90 [3.90, 3.90]0% [0%, 0%]0%0%-0.95—2026-08-30 → 2026-08-30
tmin00Znearest365d1 1 QC3.90 [3.90, 3.90]0.00-3.90 [-3.90, -3.90]3.90 [3.90, 3.90]0% [0%, 0%]0%0%-0.95—2026-08-30 → 2026-08-30
tmin00Znearestall1 1 QC3.90 [3.90, 3.90]0.00-3.90 [-3.90, -3.90]3.90 [3.90, 3.90]0% [0%, 0%]0%0%-0.95—2026-08-30 → 2026-08-30
tmin12Zbilinear30d2 1 QC2.55 [1.34, 3.75]1.20-2.55 [-3.75, -1.34]2.82 [1.34, 3.75]0% [0%, 0%]50%50%-0.88—2026-08-29 → 2026-08-30
tmin12Zbilinear90d2 1 QC2.55 [1.34, 3.75]1.20-2.55 [-3.75, -1.34]2.82 [1.34, 3.75]0% [0%, 0%]50%50%-0.88—2026-08-29 → 2026-08-30
tmin12Zbilinear365d2 1 QC2.55 [1.34, 3.75]1.20-2.55 [-3.75, -1.34]2.82 [1.34, 3.75]0% [0%, 0%]50%50%-0.88—2026-08-29 → 2026-08-30
tmin12Zbilinearall2 1 QC2.55 [1.34, 3.75]1.20-2.55 [-3.75, -1.34]2.82 [1.34, 3.75]0% [0%, 0%]50%50%-0.88—2026-08-29 → 2026-08-30
tmin12Znearest30d2 1 QC2.02 [0.94, 3.10]1.08-2.02 [-3.10, -0.94]2.29 [0.94, 3.10]50% [0%, 100%]50%50%-0.55—2026-08-29 → 2026-08-30
tmin12Znearest90d2 1 QC2.02 [0.94, 3.10]1.08-2.02 [-3.10, -0.94]2.29 [0.94, 3.10]50% [0%, 100%]50%50%-0.55—2026-08-29 → 2026-08-30
tmin12Znearest365d2 1 QC2.02 [0.94, 3.10]1.08-2.02 [-3.10, -0.94]2.29 [0.94, 3.10]50% [0%, 100%]50%50%-0.55—2026-08-29 → 2026-08-30
tmin12Znearestall2 1 QC2.02 [0.94, 3.10]1.08-2.02 [-3.10, -0.94]2.29 [0.94, 3.10]50% [0%, 100%]50%50%-0.55—2026-08-29 → 2026-08-30

+ model too warm · − model too cold · bias interval includes zero · ★ lowest MAE · = not distinguishable from the leader · ▼ significantly worse · n < 30 greyed and unranked · CI is a 95 % moving-block bootstrap interval.

Daily error, last 90 days

Daily forecast minus observed error in °F for GraphCast (GFS init) at KBOS, lead day 1, 00Z bilinear tmax+10+50-5-102026-08-30: -5.34 °F2026-08-30°F, forecast − observed
Forecast − observed, °F, 00Z bilinear daily maximum. The dashed line is zero; the thick line is a centred 7-day mean, drawn only where the whole window is present. Gaps are days with no score, never interpolation. Hover a point for its date and value.
The same series as a table (1 days, newest first) · download CSV
Climatological dayError °F
2026-08-30-5.34

Error distribution

Distribution of the signed daily error in °F for GraphCast (GFS init) at KBOS, lead day 1-10 to -9 °F: 0 days-9 to -8 °F: 0 days-8 to -7 °F: 0 days-7 to -6 °F: 0 days-6 to -5 °F: 1 day-5 to -4 °F: 0 days-4 to -3 °F: 0 days-3 to -2 °F: 0 days-2 to -1 °F: 0 days-1 to 0 °F: 0 days0 to 1 °F: 0 days1 to 2 °F: 0 days2 to 3 °F: 0 days3 to 4 °F: 0 days4 to 5 °F: 0 days5 to 6 °F: 0 days6 to 7 °F: 0 days7 to 8 °F: 0 days8 to 9 °F: 0 days9 to 10 °F: 0 daysdashed: P50 |e| 5.34 · P90 |e| 5.34 °F-100+10 °Fn = 1 days
All scored days for 00Z bilinear daily maximum, 20 equal bins. The dashed marks are the 50th and 90th percentiles of the absolute error, mirrored on both sides. Hover a bar for its bin and count.
Bin counts as a table
From °FTo °FDays
-10.00-9.000
-9.00-8.000
-8.00-7.000
-7.00-6.000
-6.00-5.001
-5.00-4.000
-4.00-3.000
-3.00-2.000
-2.00-1.000
-1.00+0.000
+0.00+1.000
+1.00+2.000
+2.00+3.000
+3.00+4.000
+4.00+5.000
+5.00+6.000
+6.00+7.000
+7.00+8.000
+8.00+9.000
+9.00+10.000

Month by month

00Z bilinear daily maximum, newest first.

Monthn MAE °FBias °F
2026-0815.34 -5.34

Availability

ModelScored period DaysCoverage
GraphCast (GFS init)2026-08-30 → 2026-08-30 1
GraphCast (GFS init)2026-08-30 → 2026-08-30 1
GraphCast (GFS init)2026-08-29 → 2026-08-30 2
GraphCast (GFS init)2026-08-29 → 2026-08-30 2

Compared with other models

Paired bootstrap on the days both models cover (90d, 00Z, bilinear, daily maximum). Negative means GraphCast (GFS init) has the lower MAE. "Distinguishable" means the 95 % interval excludes zero.

Other modelCommon days MAE difference °FDistinguishable
ECMWF AIFS Single 1 +0.79 [0.79, 0.79] yes
Aurora (GFS init) 1 -0.20 [-0.20, -0.20] yes
Aurora (IFS init) 1 +0.45 [0.45, 0.45] yes
FourCastNet v2 (GFS init) 1 -1.33 [-1.33, -1.33] yes
FourCastNet v2 (IFS init) 1 -1.76 [-1.76, -1.76] yes
NCEP GFS 1 +4.89 [4.89, 4.89] yes
GraphCast (IFS init) 1 +0.60 [0.60, 0.60] yes
ECMWF IFS HRES 1 +4.90 [4.90, 4.90] yes
Pangu-Weather (GFS init) 1 +1.84 [1.84, 1.84] yes
Pangu-Weather (IFS init) 1 +2.18 [2.18, 2.18] yes
Persistence (baseline) 1 -5.66 [-5.66, -5.66] yes

Cite this page

ShortCastCheck, KBOS graphcast_gfs lead 1, methodology v0.2, accessed 2026-08-31, https://castcheck.zifanzhang.com/station/KBOS/model/graphcast_gfs/lead/1/

LongCastCheck (2026). Station-level verification of raw weather-model 2 m temperature forecasts: KBOS (Boston Logan), model graphcast_gfs, lead day 1. Methodology version 0.2, schema version 0.1, data through 2026-08-30. Accessed 2026-08-31. https://castcheck.zifanzhang.com/station/KBOS/model/graphcast_gfs/lead/1/

Accessed2026-08-31 (data through 2026-08-30; page built 2026-08-31T03:52:06+00:00)

JSON CSV all scores methodology v0.2 licence