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

Boston Logan · GraphCast (IFS init) · lead day 5

KBOS · graphcast_ifs · lead 5

Target day = initialization date + 5 days. 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
tmax00Zbilinear30d24 1 QC4.17 [3.02, 5.40]3.90-1.41 [-2.44, -0.18]4.86 [3.63, 5.94]8% [0%, 17%]29%42%+0.39+0.412026-08-06 → 2026-08-30
tmax00Zbilinear90d24 1 QC4.17 [2.97, 5.53]3.90-1.41 [-2.51, -0.17]4.86 [3.58, 6.01]8% [0%, 16%]29%42%+0.39+0.412026-08-06 → 2026-08-30
tmax00Zbilinear365d30 1 QC4.28 [3.09, 5.48]4.02-1.40 [-2.43, -0.10]5.07 [3.69, 6.16]10% [0%, 19%]27%40%+0.48+0.512026-01-06 → 2026-08-30
tmax00Zbilinearall30 1 QC4.28 [3.08, 5.44]4.02-1.40 [-2.38, -0.20]5.07 [3.69, 6.13]10% [0%, 19%]27%40%+0.48+0.512026-01-06 → 2026-08-30
tmax00Znearest30d24 1 QC4.19 [3.00, 5.43]3.93-1.43 [-2.49, -0.14]4.89 [3.64, 5.97]8% [0%, 17%]29%38%+0.39+0.412026-08-06 → 2026-08-30
tmax00Znearest90d24 1 QC4.19 [2.98, 5.56]3.93-1.43 [-2.58, -0.11]4.89 [3.59, 6.04]8% [0%, 16%]29%38%+0.39+0.412026-08-06 → 2026-08-30
tmax00Znearest365d30 1 QC4.31 [3.05, 5.56]4.10-1.38 [-2.41, -0.07]5.13 [3.75, 6.23]10% [0%, 19%]30%37%+0.48+0.502026-01-06 → 2026-08-30
tmax00Znearestall30 1 QC4.31 [3.05, 5.51]4.10-1.38 [-2.38, -0.12]5.13 [3.72, 6.19]10% [0%, 19%]30%37%+0.48+0.502026-01-06 → 2026-08-30
tmax12Zbilinear30d24 1 QC4.55 [3.87, 5.20]4.09-2.10 [-3.25, -0.93]5.25 [4.56, 5.84]12% [4%, 22%]29%29%+0.34+0.382026-08-06 → 2026-08-30
tmax12Zbilinear90d24 1 QC4.55 [3.89, 5.28]4.09-2.10 [-3.39, -0.86]5.25 [4.55, 5.86]12% [0%, 22%]29%29%+0.34+0.382026-08-06 → 2026-08-30
tmax12Zbilinear365d29 1 QC4.30 [3.50, 5.07]3.63-2.28 [-3.26, -1.06]4.98 [4.09, 5.67]14% [0%, 24%]28%31%+0.48+0.562026-01-06 → 2026-08-30
tmax12Zbilinearall29 1 QC4.30 [3.43, 5.06]3.63-2.28 [-3.29, -1.12]4.98 [4.02, 5.67]14% [4%, 25%]28%31%+0.48+0.562026-01-06 → 2026-08-30
tmax12Znearest30d24 1 QC4.53 [3.84, 5.18]4.10-2.11 [-3.26, -0.94]5.24 [4.56, 5.82]12% [4%, 22%]29%33%+0.34+0.382026-08-06 → 2026-08-30
tmax12Znearest90d24 1 QC4.53 [3.87, 5.26]4.10-2.11 [-3.42, -0.89]5.24 [4.58, 5.86]12% [0%, 22%]29%33%+0.34+0.382026-08-06 → 2026-08-30
tmax12Znearest365d29 1 QC4.22 [3.35, 5.04]3.60-2.22 [-3.23, -1.00]4.93 [3.97, 5.64]14% [0%, 24%]28%38%+0.49+0.562026-01-06 → 2026-08-30
tmax12Znearestall29 1 QC4.22 [3.28, 5.03]3.60-2.22 [-3.25, -1.09]4.93 [3.82, 5.64]14% [4%, 25%]28%38%+0.49+0.562026-01-06 → 2026-08-30
tmin00Zbilinear30d24 1 QC1.84 [1.01, 2.51]1.83+0.09 [-0.69, 1.00]2.27 [1.49, 2.79]38% [8%, 72%]46%83%+0.45+0.432026-08-06 → 2026-08-30
tmin00Zbilinear90d24 1 QC1.84 [0.69, 2.61]1.83+0.09 [-0.77, 1.14]2.27 [1.14, 2.87]38% [4%, 86%]46%83%+0.45+0.432026-08-06 → 2026-08-30
tmin00Zbilinear365d30 1 QC2.29 [1.28, 3.45]2.33+0.48 [-0.47, 1.75]3.18 [1.79, 4.70]33% [6%, 67%]43%77%+0.56+0.572026-01-06 → 2026-08-30
tmin00Zbilinearall30 1 QC2.29 [1.30, 3.49]2.33+0.48 [-0.54, 1.63]3.18 [1.82, 4.79]33% [7%, 67%]43%77%+0.56+0.572026-01-06 → 2026-08-30
tmin00Znearest30d24 1 QC1.82 [0.96, 2.52]1.83+0.30 [-0.53, 1.24]2.27 [1.45, 2.82]38% [8%, 72%]54%79%+0.45+0.432026-08-06 → 2026-08-30
tmin00Znearest90d24 1 QC1.82 [0.63, 2.61]1.83+0.30 [-0.56, 1.42]2.27 [1.02, 2.92]38% [4%, 86%]54%79%+0.45+0.432026-08-06 → 2026-08-30
tmin00Znearest365d30 1 QC2.33 [1.23, 3.59]2.39+0.75 [-0.28, 2.14]3.26 [1.76, 4.86]33% [6%, 67%]50%73%+0.55+0.552026-01-06 → 2026-08-30
tmin00Znearestall30 1 QC2.33 [1.26, 3.64]2.39+0.75 [-0.34, 2.00]3.26 [1.79, 4.95]33% [7%, 67%]50%73%+0.55+0.552026-01-06 → 2026-08-30
tmin12Zbilinear30d24 1 QC1.73 [1.04, 2.56]1.73-0.02 [-0.73, 0.71]2.20 [1.40, 2.93]42% [12%, 71%]62%79%+0.48+0.462026-08-06 → 2026-08-30
tmin12Zbilinear90d24 1 QC1.73 [0.84, 2.71]1.73-0.02 [-0.78, 0.81]2.20 [1.12, 3.07]42% [9%, 83%]62%79%+0.48+0.462026-08-06 → 2026-08-30
tmin12Zbilinear365d29 1 QC2.00 [1.10, 3.09]1.99+0.30 [-0.55, 1.33]2.54 [1.47, 3.47]38% [8%, 67%]55%72%+0.60+0.622026-01-06 → 2026-08-30
tmin12Zbilinearall29 1 QC2.00 [1.17, 3.12]1.99+0.30 [-0.64, 1.37]2.54 [1.58, 3.47]38% [9%, 67%]55%72%+0.60+0.622026-01-06 → 2026-08-30
tmin12Znearest30d24 1 QC1.74 [1.08, 2.51]1.73+0.20 [-0.52, 0.95]2.19 [1.38, 2.88]38% [11%, 62%]58%83%+0.48+0.462026-08-06 → 2026-08-30
tmin12Znearest90d24 1 QC1.74 [0.91, 2.64]1.73+0.20 [-0.60, 1.07]2.19 [1.11, 3.02]38% [7%, 67%]58%83%+0.48+0.462026-08-06 → 2026-08-30
tmin12Znearest365d29 1 QC2.04 [1.20, 3.09]2.02+0.57 [-0.30, 1.66]2.59 [1.53, 3.57]34% [8%, 58%]52%76%+0.59+0.612026-01-06 → 2026-08-30
tmin12Znearestall29 1 QC2.04 [1.24, 3.12]2.02+0.57 [-0.40, 1.73]2.59 [1.59, 3.64]34% [9%, 59%]52%76%+0.59+0.612026-01-06 → 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 5, 00Z bilinear tmax+10+50-5-102026-08-06: +1.72 °F2026-08-07: -4.13 °F2026-08-08: -7.06 °F2026-08-09: -2.01 °F2026-08-10: +1.81 °F2026-08-11: -5.27 °F2026-08-12: -3.14 °F2026-08-13: -0.51 °F2026-08-14: -4.8 °F2026-08-15: +1.35 °F2026-08-16: -1.34 °F2026-08-17: -2.18 °F2026-08-18: +1.71 °F2026-08-19: -8.16 °F2026-08-20: -5.22 °F2026-08-21: +6.62 °F2026-08-22: +2.98 °F2026-08-23: +9.06 °F2026-08-24: -7.42 °F2026-08-25: -5.74 °F2026-08-26: +0.68 °F2026-08-27: -5.29 °F2026-08-29: +7.15 °F2026-08-30: -4.68 °F2026-08-062026-08-30°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 (25 days, newest first) · download CSV
Climatological dayError °F
2026-08-30-4.68
2026-08-29+7.15
2026-08-28—
2026-08-27-5.29
2026-08-26+0.68
2026-08-25-5.74
2026-08-24-7.42
2026-08-23+9.06
2026-08-22+2.98
2026-08-21+6.62
2026-08-20-5.22
2026-08-19-8.16
2026-08-18+1.71
2026-08-17-2.18
2026-08-16-1.34
2026-08-15+1.35
2026-08-14-4.80
2026-08-13-0.51
2026-08-12-3.14
2026-08-11-5.27
2026-08-10+1.81
2026-08-09-2.01
2026-08-08-7.06
2026-08-07-4.13
2026-08-06+1.72

Error distribution

Distribution of the signed daily error in °F for GraphCast (IFS init) at KBOS, lead day 5-20 to -18 °F: 0 days-18 to -16 °F: 0 days-16 to -14 °F: 0 days-14 to -12 °F: 0 days-12 to -10 °F: 1 day-10 to -8 °F: 1 day-8 to -6 °F: 2 days-6 to -4 °F: 8 days-4 to -2 °F: 4 days-2 to 0 °F: 3 days0 to 2 °F: 5 days2 to 4 °F: 1 day4 to 6 °F: 2 days6 to 8 °F: 2 days8 to 10 °F: 1 day10 to 12 °F: 0 days12 to 14 °F: 0 days14 to 16 °F: 0 days16 to 18 °F: 0 days18 to 20 °F: 0 daysdashed: P50 |e| 4.2 · P90 |e| 7.49 °F-200+20 °Fn = 30 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
-20.00-18.000
-18.00-16.000
-16.00-14.000
-14.00-12.000
-12.00-10.001
-10.00-8.001
-8.00-6.002
-6.00-4.008
-4.00-2.004
-2.00+0.003
+0.00+2.005
+2.00+4.001
+4.00+6.002
+6.00+8.002
+8.00+10.001
+10.00+12.000
+12.00+14.000
+14.00+16.000
+16.00+18.000
+18.00+20.000

Month by month

00Z bilinear daily maximum, newest first.

Monthn MAE °FBias °F
2026-08244.17 -1.41
2026-0164.71 -1.38

Availability

ModelScored period DaysCoverage
GraphCast (IFS init)2026-01-06 → 2026-08-30 30
GraphCast (IFS init)2026-01-06 → 2026-08-30 30
GraphCast (IFS init)2026-01-06 → 2026-08-30 29
GraphCast (IFS init)2026-01-06 → 2026-08-30 29

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 24 -0.46 [-1.33, 0.84] no
NCEP GFS 24 -0.04 [-1.12, 1.08] no
ECMWF IFS HRES 17 +0.43 [-2.64, 2.03] no
Persistence (baseline) 24 -2.71 [-4.34, -1.14] yes

Cite this page

ShortCastCheck, KBOS graphcast_ifs lead 5, methodology v0.2, accessed 2026-08-31, https://castcheck.zifanzhang.com/station/KBOS/model/graphcast_ifs/lead/5/

LongCastCheck (2026). Station-level verification of raw weather-model 2 m temperature forecasts: KBOS (Boston Logan), model graphcast_ifs, lead day 5. 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/5/

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