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

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

KBOS · graphcast_ifs · 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 2026-01-01 — 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
tmax00Zbilinear30d27 1 QC2.89 [2.46, 3.35]2.34-2.37 [-2.92, -1.80]3.58 [3.16, 4.04]30% [17%, 42%]37%48%+0.39+0.532026-08-02 → 2026-08-30
tmax00Zbilinear90d27 1 QC2.89 [2.45, 3.36]2.34-2.37 [-2.99, -1.83]3.58 [3.15, 4.05]30% [16%, 43%]37%48%+0.39+0.532026-08-02 → 2026-08-30
tmax00Zbilinear365d33 1 QC2.79 [2.39, 3.22]2.06-2.37 [-2.88, -1.85]3.41 [2.90, 3.90]24% [10%, 38%]39%52%+0.39+0.572026-01-02 → 2026-08-30
tmax00Zbilinearall33 1 QC2.79 [2.40, 3.27]2.06-2.37 [-2.88, -1.86]3.41 [2.87, 3.92]24% [10%, 38%]39%52%+0.39+0.572026-01-02 → 2026-08-30
tmax00Znearest30d27 1 QC2.88 [2.45, 3.36]2.32-2.39 [-2.93, -1.80]3.57 [3.16, 4.02]30% [17%, 42%]41%44%+0.39+0.532026-08-02 → 2026-08-30
tmax00Znearest90d27 1 QC2.88 [2.42, 3.37]2.32-2.39 [-3.04, -1.82]3.57 [3.16, 4.03]30% [16%, 43%]41%44%+0.39+0.532026-08-02 → 2026-08-30
tmax00Znearest365d33 1 QC2.71 [2.19, 3.18]2.07-2.30 [-2.83, -1.78]3.36 [2.72, 3.87]27% [16%, 39%]42%52%+0.41+0.572026-01-02 → 2026-08-30
tmax00Znearestall33 1 QC2.71 [2.22, 3.25]2.07-2.30 [-2.84, -1.78]3.36 [2.73, 3.90]27% [14%, 39%]42%52%+0.41+0.572026-01-02 → 2026-08-30
tmax12Zbilinear30d27 1 QC2.88 [2.48, 3.33]2.28-2.21 [-2.83, -1.50]3.49 [3.06, 3.96]30% [21%, 40%]41%52%+0.40+0.532026-08-02 → 2026-08-30
tmax12Zbilinear90d27 1 QC2.88 [2.47, 3.37]2.28-2.21 [-2.96, -1.56]3.49 [3.04, 3.98]30% [21%, 40%]41%52%+0.40+0.532026-08-02 → 2026-08-30
tmax12Zbilinear365d32 1 QC2.79 [2.40, 3.23]2.05-2.22 [-2.81, -1.58]3.35 [2.86, 3.85]25% [13%, 36%]41%56%+0.41+0.572026-01-02 → 2026-08-30
tmax12Zbilinearall32 1 QC2.79 [2.41, 3.29]2.05-2.22 [-2.84, -1.59]3.35 [2.85, 3.89]25% [13%, 36%]41%56%+0.41+0.572026-01-02 → 2026-08-30
tmax12Znearest30d27 1 QC2.88 [2.46, 3.36]2.26-2.23 [-2.86, -1.51]3.49 [3.06, 3.95]22% [8%, 32%]41%48%+0.40+0.542026-08-02 → 2026-08-30
tmax12Znearest90d27 1 QC2.88 [2.47, 3.38]2.26-2.23 [-3.01, -1.55]3.49 [3.01, 3.98]22% [7%, 32%]41%48%+0.40+0.542026-08-02 → 2026-08-30
tmax12Znearest365d32 1 QC2.72 [2.25, 3.20]2.04-2.18 [-2.80, -1.55]3.31 [2.74, 3.82]25% [12%, 36%]41%53%+0.42+0.582026-01-02 → 2026-08-30
tmax12Znearestall32 1 QC2.72 [2.24, 3.25]2.04-2.18 [-2.82, -1.54]3.31 [2.75, 3.85]25% [11%, 36%]41%53%+0.42+0.582026-01-02 → 2026-08-30
tmin00Zbilinear30d27 1 QC1.69 [1.40, 2.01]1.67-0.26 [-1.03, 0.57]2.07 [1.66, 2.54]37% [20%, 54%]67%89%+0.10+0.112026-08-02 → 2026-08-30
tmin00Zbilinear90d27 1 QC1.69 [1.39, 2.15]1.67-0.26 [-1.31, 0.61]2.07 [1.65, 2.74]37% [21%, 57%]67%89%+0.10+0.112026-08-02 → 2026-08-30
tmin00Zbilinear365d33 1 QC1.77 [1.44, 2.18]1.73-0.43 [-1.50, 0.53]2.12 [1.71, 2.68]30% [12%, 50%]64%85%+0.28+0.322026-01-02 → 2026-08-30
tmin00Zbilinearall33 1 QC1.77 [1.44, 2.21]1.73-0.43 [-1.42, 0.39]2.12 [1.72, 2.71]30% [13%, 50%]64%85%+0.28+0.322026-01-02 → 2026-08-30
tmin00Znearest30d27 1 QC1.62 [1.36, 1.91]1.62+0.03 [-0.72, 0.84]2.01 [1.62, 2.45]44% [27%, 65%]70%85%+0.13+0.142026-08-02 → 2026-08-30
tmin00Znearest90d27 1 QC1.62 [1.34, 2.02]1.62+0.03 [-0.96, 0.89]2.01 [1.58, 2.64]44% [25%, 67%]70%85%+0.13+0.142026-08-02 → 2026-08-30
tmin00Znearest365d33 1 QC1.70 [1.44, 2.06]1.70-0.09 [-1.09, 0.81]2.04 [1.68, 2.52]39% [22%, 61%]67%88%+0.31+0.332026-01-02 → 2026-08-30
tmin00Znearestall33 1 QC1.70 [1.43, 2.09]1.70-0.09 [-1.04, 0.67]2.04 [1.69, 2.56]39% [21%, 61%]67%88%+0.31+0.332026-01-02 → 2026-08-30
tmin12Zbilinear30d27 1 QC1.49 [1.18, 1.82]1.47-0.40 [-1.15, 0.29]1.90 [1.52, 2.38]37% [17%, 59%]67%96%+0.21+0.232026-08-02 → 2026-08-30
tmin12Zbilinear90d27 1 QC1.49 [1.14, 2.00]1.47-0.40 [-1.42, 0.38]1.90 [1.51, 2.56]37% [17%, 62%]67%96%+0.21+0.232026-08-02 → 2026-08-30
tmin12Zbilinear365d32 1 QC1.54 [1.19, 2.03]1.48-0.60 [-1.69, 0.20]1.95 [1.56, 2.56]38% [19%, 60%]62%94%+0.35+0.382026-01-02 → 2026-08-30
tmin12Zbilinearall32 1 QC1.54 [1.17, 2.02]1.48-0.60 [-1.60, 0.17]1.95 [1.55, 2.56]38% [20%, 59%]62%94%+0.35+0.382026-01-02 → 2026-08-30
tmin12Znearest30d27 1 QC1.46 [1.22, 1.71]1.46-0.12 [-0.85, 0.57]1.85 [1.55, 2.26]52% [34%, 69%]70%93%+0.23+0.232026-08-02 → 2026-08-30
tmin12Znearest90d27 1 QC1.46 [1.21, 1.86]1.46-0.12 [-1.09, 0.66]1.85 [1.56, 2.42]52% [32%, 70%]70%93%+0.23+0.232026-08-02 → 2026-08-30
tmin12Znearest365d32 1 QC1.51 [1.25, 1.88]1.49-0.28 [-1.29, 0.49]1.87 [1.59, 2.36]47% [29%, 67%]66%94%+0.36+0.372026-01-02 → 2026-08-30
tmin12Znearestall32 1 QC1.51 [1.24, 1.86]1.49-0.28 [-1.23, 0.47]1.87 [1.60, 2.37]47% [29%, 67%]66%94%+0.36+0.372026-01-02 → 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 (IFS init) at KBOS, lead day 1, 00Z bilinear tmax+10+50-5-102026-08-02: -3.79 °F2026-08-03: -0.45 °F2026-08-04: -4.82 °F2026-08-05: -3.65 °F2026-08-06: +0.86 °F2026-08-07: -3.38 °F2026-08-08: -5 °F2026-08-09: -0.24 °F2026-08-10: +0.19 °F2026-08-11: -3.41 °F2026-08-12: -1.33 °F2026-08-13: -5.12 °F2026-08-14: -5.36 °F2026-08-15: +0.24 °F2026-08-16: -3.88 °F2026-08-17: -2.95 °F2026-08-18: +0.42 °F2026-08-19: -7.29 °F2026-08-20: -2.59 °F2026-08-21: +2.15 °F2026-08-22: -1.45 °F2026-08-23: +3.13 °F2026-08-24: -6.9 °F2026-08-25: -4.37 °F2026-08-26: -0.09 °F2026-08-29: -0.26 °F2026-08-30: -4.74 °F2026-08-022026-08-30°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 (29 days, newest first) · download CSV
Climatological dayError °F
2026-08-30-4.74
2026-08-29-0.26
2026-08-28—
2026-08-27—
2026-08-26-0.09
2026-08-25-4.37
2026-08-24-6.90
2026-08-23+3.13
2026-08-22-1.45
2026-08-21+2.15
2026-08-20-2.59
2026-08-19-7.29
2026-08-18+0.42
2026-08-17-2.95
2026-08-16-3.88
2026-08-15+0.24
2026-08-14-5.36
2026-08-13-5.12
2026-08-12-1.33
2026-08-11-3.41
2026-08-10+0.19
2026-08-09-0.24
2026-08-08-5.00
2026-08-07-3.38
2026-08-06+0.86
2026-08-05-3.65
2026-08-04-4.82
2026-08-03-0.45
2026-08-02-3.79

Error distribution

Distribution of the signed daily error in °F for GraphCast (IFS init) at KBOS, lead day 1-10 to -9 °F: 0 days-9 to -8 °F: 0 days-8 to -7 °F: 1 day-7 to -6 °F: 1 day-6 to -5 °F: 2 days-5 to -4 °F: 4 days-4 to -3 °F: 7 days-3 to -2 °F: 3 days-2 to -1 °F: 5 days-1 to 0 °F: 4 days0 to 1 °F: 4 days1 to 2 °F: 0 days2 to 3 °F: 1 day3 to 4 °F: 1 day4 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| 2.95 · P90 |e| 5.09 °F-100+10 °Fn = 33 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
-8.00-7.001
-7.00-6.001
-6.00-5.002
-5.00-4.004
-4.00-3.007
-3.00-2.003
-2.00-1.005
-1.00+0.004
+0.00+1.004
+1.00+2.000
+2.00+3.001
+3.00+4.001
+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
2026-08272.89 -2.37
2026-0162.35 -2.35

Availability

ModelScored period DaysCoverage
GraphCast (IFS init)2026-01-02 → 2026-08-30 33
GraphCast (IFS init)2026-01-02 → 2026-08-30 33
GraphCast (IFS init)2026-01-02 → 2026-08-30 32
GraphCast (IFS init)2026-01-02 → 2026-08-30 32

Compared with other models

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

Other modelCommon days MAE difference °FDistinguishable
ECMWF AIFS Single 27 -0.40 [-0.96, 0.04] no
Aurora (GFS init) 1 -0.81 [-0.81, -0.81] yes
Aurora (IFS init) 2 -0.51 [-0.87, -0.15] yes
FourCastNet v2 (GFS init) 1 -1.93 [-1.93, -1.93] yes
FourCastNet v2 (IFS init) 2 -2.28 [-2.36, -2.21] yes
NCEP GFS 27 +0.12 [-0.89, 1.00] no
GraphCast (GFS init) 1 -0.60 [-0.60, -0.60] yes
ECMWF IFS HRES 21 +0.47 [-0.25, 1.42] no
Pangu-Weather (GFS init) 1 +1.24 [1.24, 1.24] yes
Pangu-Weather (IFS init) 2 -0.13 [-1.84, 1.58] no
Persistence (baseline) 26 -1.93 [-3.33, -1.01] yes

Cite this page

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

LongCastCheck (2026). Station-level verification of raw weather-model 2 m temperature forecasts: KBOS (Boston Logan), model graphcast_ifs, 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_ifs/lead/1/

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

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