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

Boston Logan · GraphCast (IFS init) · lead day 9

KBOS · graphcast_ifs · lead 9

Target day = initialization date + 9 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
tmax00Zbilinear30d20 1 QC5.39 [4.10, 6.86]5.28-1.26 [-4.61, 1.96]6.47 [5.04, 7.85]5% [0%, 13%]25%30%+0.32+0.332026-08-10 → 2026-08-30
tmax00Zbilinear90d20 1 QC5.39 [4.15, 6.87]5.28-1.26 [-5.11, 2.18]6.47 [5.09, 7.85]5% [0%, 13%]25%30%+0.32+0.332026-08-10 → 2026-08-30
tmax00Zbilinear365d26 1 QC5.84 [4.02, 8.16]5.35-2.67 [-6.95, 0.83]7.57 [5.03, 10.62]8% [0%, 19%]23%31%+0.40+0.452026-01-10 → 2026-08-30
tmax00Zbilinearall26 1 QC5.84 [4.13, 8.56]5.35-2.67 [-7.27, 1.06]7.57 [5.21, 10.88]8% [0%, 18%]23%31%+0.40+0.452026-01-10 → 2026-08-30
tmax00Znearest30d20 1 QC5.38 [4.06, 6.87]5.25-1.26 [-4.67, 1.97]6.46 [5.02, 7.85]5% [0%, 13%]30%35%+0.32+0.332026-08-10 → 2026-08-30
tmax00Znearest90d20 1 QC5.38 [4.10, 6.86]5.25-1.26 [-5.18, 2.01]6.46 [5.07, 7.86]5% [0%, 13%]30%35%+0.32+0.332026-08-10 → 2026-08-30
tmax00Znearest365d26 1 QC5.78 [3.95, 8.05]5.31-2.62 [-6.83, 0.84]7.50 [5.01, 10.47]8% [0%, 19%]27%35%+0.41+0.462026-01-10 → 2026-08-30
tmax00Znearestall26 1 QC5.78 [4.11, 8.44]5.31-2.62 [-7.14, 1.05]7.50 [5.16, 10.76]8% [0%, 18%]27%35%+0.41+0.462026-01-10 → 2026-08-30
tmax12Zbilinear30d20 1 QC4.74 [3.31, 7.31]4.37-3.19 [-6.31, -0.98]6.28 [4.60, 9.01]20% [0%, 38%]35%45%+0.40+0.442026-08-10 → 2026-08-30
tmax12Zbilinear90d20 1 QC4.74 [3.19, 8.05]4.37-3.19 [-7.55, -0.41]6.28 [4.39, 9.70]20% [0%, 40%]35%45%+0.40+0.442026-08-10 → 2026-08-30
tmax12Zbilinear365d25 1 QC5.56 [3.65, 8.85]4.89-3.27 [-6.37, -1.08]7.03 [4.92, 9.76]16% [0%, 33%]28%36%+0.41+0.482026-01-10 → 2026-08-30
tmax12Zbilinearall25 1 QC5.56 [3.60, 9.04]4.89-3.27 [-6.45, -1.25]7.03 [4.81, 10.16]16% [0%, 34%]28%36%+0.41+0.482026-01-10 → 2026-08-30
tmax12Znearest30d20 1 QC4.75 [3.37, 7.36]4.39-3.16 [-6.32, -0.91]6.28 [4.56, 9.05]20% [4%, 32%]35%50%+0.40+0.442026-08-10 → 2026-08-30
tmax12Znearest90d20 1 QC4.75 [3.23, 8.08]4.39-3.16 [-7.59, -0.30]6.28 [4.34, 9.76]20% [0%, 31%]35%50%+0.40+0.442026-08-10 → 2026-08-30
tmax12Znearest365d25 1 QC5.49 [3.69, 8.50]4.83-3.17 [-6.26, -1.05]6.94 [4.89, 9.59]16% [0%, 27%]28%40%+0.42+0.492026-01-10 → 2026-08-30
tmax12Znearestall25 1 QC5.49 [3.65, 8.83]4.83-3.17 [-6.33, -1.14]6.94 [4.77, 9.91]16% [0%, 27%]28%40%+0.42+0.492026-01-10 → 2026-08-30
tmin00Zbilinear30d20 1 QC3.66 [2.98, 4.66]3.66+0.11 [-2.02, 1.78]4.20 [3.54, 5.23]10% [0%, 20%]20%55%+0.08+0.052026-08-10 → 2026-08-30
tmin00Zbilinear90d20 1 QC3.66 [2.95, 4.90]3.66+0.11 [-2.33, 2.03]4.20 [3.51, 5.42]10% [0%, 19%]20%55%+0.08+0.052026-08-10 → 2026-08-30
tmin00Zbilinear365d26 1 QC3.92 [2.99, 5.37]3.78-0.91 [-3.71, 1.31]4.68 [3.61, 6.12]8% [0%, 16%]27%54%+0.38+0.422026-01-10 → 2026-08-30
tmin00Zbilinearall26 1 QC3.92 [3.02, 5.36]3.78-0.91 [-4.10, 1.34]4.68 [3.66, 6.25]8% [0%, 16%]27%54%+0.38+0.422026-01-10 → 2026-08-30
tmin00Znearest30d20 1 QC3.62 [2.92, 4.61]3.62+0.35 [-1.75, 1.97]4.16 [3.46, 5.08]15% [0%, 29%]20%60%+0.10+0.062026-08-10 → 2026-08-30
tmin00Znearest90d20 1 QC3.62 [2.87, 4.73]3.62+0.35 [-2.03, 2.23]4.16 [3.45, 5.21]15% [0%, 29%]20%60%+0.10+0.062026-08-10 → 2026-08-30
tmin00Znearest365d26 1 QC3.82 [2.88, 5.09]3.73-0.63 [-3.35, 1.51]4.56 [3.54, 5.83]19% [0%, 33%]27%58%+0.40+0.432026-01-10 → 2026-08-30
tmin00Znearestall26 1 QC3.82 [2.90, 5.15]3.73-0.63 [-3.70, 1.59]4.56 [3.57, 5.93]19% [0%, 33%]27%58%+0.40+0.432026-01-10 → 2026-08-30
tmin12Zbilinear30d20 1 QC3.08 [2.15, 4.65]2.95-1.14 [-3.74, 0.60]3.90 [2.81, 5.50]20% [5%, 38%]40%50%+0.23+0.242026-08-10 → 2026-08-30
tmin12Zbilinear90d20 1 QC3.08 [2.01, 5.28]2.95-1.14 [-4.97, 0.96]3.90 [2.62, 5.85]20% [0%, 42%]40%50%+0.23+0.242026-08-10 → 2026-08-30
tmin12Zbilinear365d25 1 QC3.38 [2.29, 5.17]3.22-1.41 [-4.09, 0.49]4.18 [2.97, 5.74]20% [5%, 36%]36%44%+0.48+0.522026-01-10 → 2026-08-30
tmin12Zbilinearall25 1 QC3.38 [2.43, 5.13]3.22-1.41 [-4.12, 0.27]4.18 [3.08, 5.79]20% [6%, 33%]36%44%+0.48+0.522026-01-10 → 2026-08-30
tmin12Znearest30d20 1 QC3.00 [2.08, 4.45]2.93-0.89 [-3.47, 0.83]3.77 [2.74, 5.18]25% [8%, 40%]40%55%+0.25+0.242026-08-10 → 2026-08-30
tmin12Znearest90d20 1 QC3.00 [1.91, 4.97]2.93-0.89 [-4.63, 1.18]3.77 [2.52, 5.49]25% [0%, 43%]40%55%+0.25+0.242026-08-10 → 2026-08-30
tmin12Znearest365d25 1 QC3.29 [2.24, 4.92]3.19-1.11 [-3.73, 0.69]4.01 [2.94, 5.38]24% [8%, 38%]36%48%+0.49+0.532026-01-10 → 2026-08-30
tmin12Znearestall25 1 QC3.29 [2.39, 4.94]3.19-1.11 [-3.77, 0.51]4.01 [3.04, 5.43]24% [7%, 36%]36%48%+0.49+0.532026-01-10 → 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 9, 00Z bilinear tmax+20+100-10-202026-08-10: +2.19 °F2026-08-11: -8.13 °F2026-08-12: +1.79 °F2026-08-13: -9.21 °F2026-08-14: -5.77 °F2026-08-15: +1.74 °F2026-08-16: -5.27 °F2026-08-17: +1.26 °F2026-08-18: +0.44 °F2026-08-19: -7.36 °F2026-08-20: +3.47 °F2026-08-21: +6.34 °F2026-08-22: +14.08 °F2026-08-23: +9.92 °F2026-08-24: -5.25 °F2026-08-25: -6.53 °F2026-08-26: -3.04 °F2026-08-27: -4.44 °F2026-08-29: -1.03 °F2026-08-30: -10.44 °F2026-08-102026-08-30°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 (21 days, newest first) · download CSV
Climatological dayError °F
2026-08-30-10.44
2026-08-29-1.03
2026-08-28—
2026-08-27-4.44
2026-08-26-3.04
2026-08-25-6.53
2026-08-24-5.25
2026-08-23+9.92
2026-08-22+14.08
2026-08-21+6.34
2026-08-20+3.47
2026-08-19-7.36
2026-08-18+0.44
2026-08-17+1.26
2026-08-16-5.27
2026-08-15+1.74
2026-08-14-5.77
2026-08-13-9.21
2026-08-12+1.79
2026-08-11-8.13
2026-08-10+2.19

Error distribution

Distribution of the signed daily error in °F for GraphCast (IFS init) at KBOS, lead day 9-25 to -22.5 °F: 1 day-22.5 to -20 °F: 0 days-20 to -17.5 °F: 0 days-17.5 to -15 °F: 0 days-15 to -12.5 °F: 0 days-12.5 to -10 °F: 1 day-10 to -7.5 °F: 3 days-7.5 to -5 °F: 6 days-5 to -2.5 °F: 3 days-2.5 to 0 °F: 3 days0 to 2.5 °F: 5 days2.5 to 5 °F: 1 day5 to 7.5 °F: 1 day7.5 to 10 °F: 1 day10 to 12.5 °F: 0 days12.5 to 15 °F: 1 day15 to 17.5 °F: 0 days17.5 to 20 °F: 0 days20 to 22.5 °F: 0 days22.5 to 25 °F: 0 daysdashed: P50 |e| 5.19 · P90 |e| 10.18 °F-250+25 °Fn = 26 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
-25.00-22.501
-22.50-20.000
-20.00-17.500
-17.50-15.000
-15.00-12.500
-12.50-10.001
-10.00-7.503
-7.50-5.006
-5.00-2.503
-2.50+0.003
+0.00+2.505
+2.50+5.001
+5.00+7.501
+7.50+10.001
+10.00+12.500
+12.50+15.001
+15.00+17.500
+17.50+20.000
+20.00+22.500
+22.50+25.000

Month by month

00Z bilinear daily maximum, newest first.

Monthn MAE °FBias °F
2026-08205.39 -1.26
2026-0167.35 -7.35

Availability

ModelScored period DaysCoverage
GraphCast (IFS init)2026-01-10 → 2026-08-30 26
GraphCast (IFS init)2026-01-10 → 2026-08-30 26
GraphCast (IFS init)2026-01-10 → 2026-08-30 25
GraphCast (IFS init)2026-01-10 → 2026-08-30 25

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 20 -0.88 [-2.46, 0.90] no
NCEP GFS 20 -1.77 [-4.33, -0.05] yes
ECMWF IFS HRES 15 +1.08 [-0.90, 2.59] no
Persistence (baseline) 20 -2.56 [-5.89, 1.50] no

Cite this page

ShortCastCheck, KBOS graphcast_ifs lead 9, methodology v0.2, accessed 2026-08-31, https://castcheck.zifanzhang.com/station/KBOS/model/graphcast_ifs/lead/9/

LongCastCheck (2026). Station-level verification of raw weather-model 2 m temperature forecasts: KBOS (Boston Logan), model graphcast_ifs, lead day 9. 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/9/

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