Raw model output on the native 0.25° grid — no MOS, no bias correction, no post-processing. Scores understate operational forecast quality. Read the fairness statement →

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

Boston Logan · GraphCast (IFS init) · lead day 7

KBOS · graphcast_ifs · lead 7

Target day = initialization date + 7 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
tmax00Zbilinear30d22 1 QC4.52 [3.03, 6.16]4.21-1.85 [-4.34, -0.08]5.68 [3.89, 7.21]14% [0%, 26%]36%45%+0.36+0.412026-08-08 → 2026-08-30
tmax00Zbilinear90d22 1 QC4.52 [2.87, 6.37]4.21-1.85 [-5.19, -0.09]5.68 [3.32, 7.31]14% [0%, 25%]36%45%+0.36+0.412026-08-08 → 2026-08-30
tmax00Zbilinear365d28 1 QC4.71 [3.03, 6.16]4.48-1.64 [-3.98, 0.14]5.81 [3.93, 7.10]11% [0%, 21%]36%43%+0.47+0.492026-01-08 → 2026-08-30
tmax00Zbilinearall28 1 QC4.71 [3.31, 6.21]4.48-1.64 [-4.24, 0.13]5.81 [4.20, 7.15]11% [0%, 22%]36%43%+0.47+0.492026-01-08 → 2026-08-30
tmax00Znearest30d22 1 QC4.55 [3.08, 6.16]4.22-1.89 [-4.36, -0.16]5.65 [3.86, 7.19]14% [0%, 25%]32%45%+0.35+0.412026-08-08 → 2026-08-30
tmax00Znearest90d22 1 QC4.55 [2.92, 6.36]4.22-1.89 [-5.22, -0.15]5.65 [3.35, 7.27]14% [0%, 25%]32%45%+0.35+0.412026-08-08 → 2026-08-30
tmax00Znearest365d28 1 QC4.70 [3.08, 6.10]4.44-1.61 [-4.02, 0.20]5.74 [3.88, 7.03]11% [0%, 21%]29%43%+0.47+0.492026-01-08 → 2026-08-30
tmax00Znearestall28 1 QC4.70 [3.33, 6.15]4.44-1.61 [-4.24, 0.16]5.74 [4.12, 7.07]11% [0%, 21%]29%43%+0.47+0.492026-01-08 → 2026-08-30
tmax12Zbilinear30d22 1 QC4.40 [3.30, 5.51]3.68-2.97 [-4.61, -1.37]5.79 [4.23, 7.00]18% [11%, 28%]23%45%+0.37+0.492026-08-08 → 2026-08-30
tmax12Zbilinear90d22 1 QC4.40 [3.02, 5.56]3.68-2.97 [-4.84, -1.42]5.79 [3.72, 7.06]18% [10%, 33%]23%45%+0.37+0.492026-08-08 → 2026-08-30
tmax12Zbilinear365d27 1 QC4.38 [3.35, 5.28]3.84-2.40 [-4.37, -0.31]5.63 [3.89, 6.69]15% [6%, 25%]22%44%+0.50+0.562026-01-08 → 2026-08-30
tmax12Zbilinearall27 1 QC4.38 [3.40, 5.27]3.84-2.40 [-4.31, -0.37]5.63 [4.09, 6.63]15% [5%, 25%]22%44%+0.50+0.562026-01-08 → 2026-08-30
tmax12Znearest30d22 1 QC4.33 [3.20, 5.42]3.61-2.99 [-4.62, -1.44]5.74 [4.15, 6.95]18% [11%, 28%]32%41%+0.39+0.492026-08-08 → 2026-08-30
tmax12Znearest90d22 1 QC4.33 [2.92, 5.46]3.61-2.99 [-4.79, -1.55]5.74 [3.64, 7.00]18% [10%, 33%]32%41%+0.39+0.492026-08-08 → 2026-08-30
tmax12Znearest365d27 1 QC4.33 [3.26, 5.21]3.81-2.41 [-4.32, -0.31]5.61 [3.86, 6.61]15% [6%, 25%]30%41%+0.51+0.572026-01-08 → 2026-08-30
tmax12Znearestall27 1 QC4.33 [3.31, 5.19]3.81-2.41 [-4.34, -0.35]5.61 [4.09, 6.57]15% [5%, 25%]30%41%+0.51+0.572026-01-08 → 2026-08-30
tmin00Zbilinear30d22 1 QC2.38 [1.77, 3.10]2.36-0.10 [-1.28, 1.00]2.70 [2.01, 3.35]23% [9%, 33%]36%73%+0.38+0.342026-08-08 → 2026-08-30
tmin00Zbilinear90d22 1 QC2.38 [1.73, 3.14]2.36-0.10 [-1.52, 1.29]2.70 [1.97, 3.38]23% [8%, 33%]36%73%+0.38+0.342026-08-08 → 2026-08-30
tmin00Zbilinear365d28 1 QC2.55 [1.84, 3.30]2.58+0.39 [-0.98, 1.82]2.96 [2.05, 3.69]21% [9%, 33%]36%68%+0.56+0.572026-01-08 → 2026-08-30
tmin00Zbilinearall28 1 QC2.55 [1.86, 3.26]2.58+0.39 [-1.01, 1.78]2.96 [2.11, 3.65]21% [10%, 32%]36%68%+0.56+0.572026-01-08 → 2026-08-30
tmin00Znearest30d22 1 QC2.29 [1.65, 3.03]2.32+0.16 [-0.95, 1.25]2.65 [1.88, 3.35]18% [7%, 31%]41%77%+0.40+0.362026-08-08 → 2026-08-30
tmin00Znearest90d22 1 QC2.29 [1.61, 3.09]2.32+0.16 [-1.15, 1.50]2.65 [1.85, 3.38]18% [5%, 33%]41%77%+0.40+0.362026-08-08 → 2026-08-30
tmin00Znearest365d28 1 QC2.50 [1.71, 3.36]2.54+0.67 [-0.66, 2.12]2.98 [1.92, 3.82]18% [6%, 31%]39%71%+0.57+0.572026-01-08 → 2026-08-30
tmin00Znearestall28 1 QC2.50 [1.71, 3.28]2.54+0.67 [-0.71, 2.10]2.98 [1.95, 3.77]18% [7%, 30%]39%71%+0.57+0.572026-01-08 → 2026-08-30
tmin12Zbilinear30d22 1 QC1.97 [1.51, 2.50]1.90-0.36 [-1.16, 0.54]2.36 [1.80, 2.89]32% [17%, 44%]41%82%+0.48+0.472026-08-08 → 2026-08-30
tmin12Zbilinear90d22 1 QC1.97 [1.51, 2.50]1.90-0.36 [-1.17, 0.64]2.36 [1.79, 2.91]32% [15%, 43%]41%82%+0.48+0.472026-08-08 → 2026-08-30
tmin12Zbilinear365d27 1 QC2.47 [1.61, 3.77]2.47-0.01 [-1.05, 1.48]3.24 [1.87, 4.74]30% [14%, 42%]41%74%+0.57+0.582026-01-08 → 2026-08-30
tmin12Zbilinearall27 1 QC2.47 [1.61, 3.94]2.47-0.01 [-1.19, 1.46]3.24 [1.92, 4.93]30% [14%, 42%]41%74%+0.57+0.582026-01-08 → 2026-08-30
tmin12Znearest30d22 1 QC1.89 [1.40, 2.45]1.87-0.11 [-0.89, 0.80]2.31 [1.67, 2.90]36% [20%, 50%]50%82%+0.50+0.482026-08-08 → 2026-08-30
tmin12Znearest90d22 1 QC1.89 [1.43, 2.44]1.87-0.11 [-0.92, 0.91]2.31 [1.69, 2.91]36% [18%, 50%]50%82%+0.50+0.482026-08-08 → 2026-08-30
tmin12Znearest365d27 1 QC2.43 [1.52, 3.82]2.48+0.26 [-0.80, 1.75]3.25 [1.77, 4.82]33% [17%, 50%]48%74%+0.58+0.582026-01-08 → 2026-08-30
tmin12Znearestall27 1 QC2.43 [1.52, 4.00]2.48+0.26 [-0.87, 1.76]3.25 [1.78, 5.04]33% [15%, 47%]48%74%+0.58+0.582026-01-08 → 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 7, 00Z bilinear tmax+20+100-10-202026-08-08: -4.28 °F2026-08-09: -2.07 °F2026-08-10: +1.79 °F2026-08-11: -3.39 °F2026-08-12: -1.46 °F2026-08-13: -1.33 °F2026-08-14: -6.14 °F2026-08-15: +0.85 °F2026-08-16: -0.53 °F2026-08-17: +9.52 °F2026-08-18: +1.23 °F2026-08-19: -6.77 °F2026-08-20: -6.32 °F2026-08-21: +2.69 °F2026-08-22: +5.35 °F2026-08-23: +7.8 °F2026-08-24: -11.7 °F2026-08-25: -8.71 °F2026-08-26: +0.16 °F2026-08-27: -4.4 °F2026-08-29: -1.99 °F2026-08-30: -10.9 °F2026-08-082026-08-30°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 (23 days, newest first) · download CSV
Climatological dayError °F
2026-08-30-10.90
2026-08-29-1.99
2026-08-28—
2026-08-27-4.40
2026-08-26+0.16
2026-08-25-8.71
2026-08-24-11.70
2026-08-23+7.80
2026-08-22+5.35
2026-08-21+2.69
2026-08-20-6.32
2026-08-19-6.77
2026-08-18+1.23
2026-08-17+9.52
2026-08-16-0.53
2026-08-15+0.85
2026-08-14-6.14
2026-08-13-1.33
2026-08-12-1.46
2026-08-11-3.39
2026-08-10+1.79
2026-08-09-2.07
2026-08-08-4.28

Error distribution

Distribution of the signed daily error in °F for GraphCast (IFS init) at KBOS, lead day 7-20 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: 2 days-10 to -8 °F: 1 day-8 to -6 °F: 4 days-6 to -4 °F: 4 days-4 to -2 °F: 2 days-2 to 0 °F: 4 days0 to 2 °F: 6 days2 to 4 °F: 1 day4 to 6 °F: 1 day6 to 8 °F: 1 day8 to 10 °F: 1 day10 to 12 °F: 1 day12 to 14 °F: 0 days14 to 16 °F: 0 days16 to 18 °F: 0 days18 to 20 °F: 0 daysdashed: P50 |e| 4.34 · P90 |e| 9.83 °F-200+20 °Fn = 28 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
-12.00-10.002
-10.00-8.001
-8.00-6.004
-6.00-4.004
-4.00-2.002
-2.00+0.004
+0.00+2.006
+2.00+4.001
+4.00+6.001
+6.00+8.001
+8.00+10.001
+10.00+12.001
+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
2026-08224.52 -1.85
2026-0165.44 -0.87

Availability

ModelScored period DaysCoverage
GraphCast (IFS init)2026-01-08 → 2026-08-30 28
GraphCast (IFS init)2026-01-08 → 2026-08-30 28
GraphCast (IFS init)2026-01-08 → 2026-08-30 27
GraphCast (IFS init)2026-01-08 → 2026-08-30 27

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 22 -0.35 [-2.94, 1.34] no
NCEP GFS 22 -0.97 [-2.23, 0.72] no
ECMWF IFS HRES 17 +0.89 [-1.59, 2.04] no
Persistence (baseline) 22 -2.53 [-4.35, -0.71] yes

Cite this page

ShortCastCheck, KBOS graphcast_ifs lead 7, methodology v0.2, accessed 2026-08-31, https://castcheck.zifanzhang.com/station/KBOS/model/graphcast_ifs/lead/7/

LongCastCheck (2026). Station-level verification of raw weather-model 2 m temperature forecasts: KBOS (Boston Logan), model graphcast_ifs, lead day 7. 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/7/

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