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

Boston Logan · NCEP GFS · lead day 0

KBOS · gfs · lead 0

Target day = initialization date + 0 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, gfs-0p25, starting 2026-08-01 — 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
tmax00Zbilinear30d29 1 QC2.22 [1.79, 2.57]2.08-0.80 [-1.59, -0.10]2.68 [2.18, 3.07]21% [7%, 33%]41%83%——2026-08-01 → 2026-08-30
tmax00Zbilinear90d29 1 QC2.22 [1.72, 2.61]2.08-0.80 [-1.76, 0.09]2.68 [2.11, 3.11]21% [9%, 36%]41%83%——2026-08-01 → 2026-08-30
tmax00Zbilinear365d29 1 QC2.22 [1.76, 2.62]2.08-0.80 [-1.69, 0.15]2.68 [2.09, 3.12]21% [9%, 36%]41%83%——2026-08-01 → 2026-08-30
tmax00Zbilinearall29 1 QC2.22 [1.78, 2.62]2.08-0.80 [-1.86, 0.17]2.68 [2.13, 3.18]21% [7%, 36%]41%83%——2026-08-01 → 2026-08-30
tmax00Znearest30d29 1 QC2.27 [1.95, 2.62]2.01-1.41 [-2.16, -0.80]2.81 [2.36, 3.25]24% [14%, 33%]55%69%——2026-08-01 → 2026-08-30
tmax00Znearest90d29 1 QC2.27 [1.87, 2.69]2.01-1.41 [-2.26, -0.69]2.81 [2.28, 3.30]24% [12%, 37%]55%69%——2026-08-01 → 2026-08-30
tmax00Znearest365d29 1 QC2.27 [1.86, 2.68]2.01-1.41 [-2.24, -0.58]2.81 [2.25, 3.31]24% [12%, 38%]55%69%——2026-08-01 → 2026-08-30
tmax00Znearestall29 1 QC2.27 [1.86, 2.70]2.01-1.41 [-2.36, -0.66]2.81 [2.24, 3.34]24% [12%, 36%]55%69%——2026-08-01 → 2026-08-30
tmin00Zbilinear30d29 1 QC1.55 [1.09, 1.94]1.44-0.83 [-1.52, -0.09]2.06 [1.58, 2.41]48% [28%, 70%]69%83%——2026-08-01 → 2026-08-30
tmin00Zbilinear90d29 1 QC1.55 [1.02, 2.01]1.44-0.83 [-1.62, -0.12]2.06 [1.53, 2.48]48% [26%, 74%]69%83%——2026-08-01 → 2026-08-30
tmin00Zbilinear365d29 1 QC1.55 [0.98, 2.02]1.44-0.83 [-1.66, -0.05]2.06 [1.46, 2.53]48% [24%, 75%]69%83%——2026-08-01 → 2026-08-30
tmin00Zbilinearall29 1 QC1.55 [1.08, 2.01]1.44-0.83 [-1.70, -0.05]2.06 [1.55, 2.54]48% [25%, 73%]69%83%——2026-08-01 → 2026-08-30
tmin00Znearest30d29 1 QC1.58 [1.05, 2.09]1.60-0.45 [-1.19, 0.32]2.11 [1.54, 2.57]48% [33%, 70%]69%79%——2026-08-01 → 2026-08-30
tmin00Znearest90d29 1 QC1.58 [0.97, 2.11]1.60-0.45 [-1.27, 0.31]2.11 [1.44, 2.60]48% [31%, 71%]69%79%——2026-08-01 → 2026-08-30
tmin00Znearest365d29 1 QC1.58 [0.91, 2.19]1.60-0.45 [-1.32, 0.37]2.11 [1.44, 2.67]48% [30%, 75%]69%79%——2026-08-01 → 2026-08-30
tmin00Znearestall29 1 QC1.58 [0.97, 2.15]1.60-0.45 [-1.35, 0.37]2.11 [1.48, 2.62]48% [31%, 71%]69%79%——2026-08-01 → 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 NCEP GFS at KBOS, lead day 0, 00Z bilinear tmax+10+50-5-102026-08-01: -2.46 °F2026-08-02: -0.98 °F2026-08-03: -6.65 °F2026-08-04: -1.73 °F2026-08-05: +0.21 °F2026-08-06: -1.19 °F2026-08-07: -2.15 °F2026-08-08: -0.16 °F2026-08-09: +2.46 °F2026-08-10: +1.08 °F2026-08-11: -2.02 °F2026-08-12: -1.79 °F2026-08-13: -3.47 °F2026-08-14: -2.75 °F2026-08-15: +2.25 °F2026-08-16: -0.61 °F2026-08-17: -5.69 °F2026-08-18: +0.4 °F2026-08-19: -2.22 °F2026-08-20: +2.53 °F2026-08-21: +2.28 °F2026-08-22: -2.55 °F2026-08-23: +2.7 °F2026-08-24: -1.59 °F2026-08-25: -1.31 °F2026-08-26: +3.7 °F2026-08-27: -4.49 °F2026-08-29: +2.8 °F2026-08-30: +0.18 °F2026-08-012026-08-30°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 (30 days, newest first) · download CSV
Climatological dayError °F
2026-08-30+0.18
2026-08-29+2.80
2026-08-28—
2026-08-27-4.49
2026-08-26+3.70
2026-08-25-1.31
2026-08-24-1.59
2026-08-23+2.70
2026-08-22-2.55
2026-08-21+2.28
2026-08-20+2.53
2026-08-19-2.22
2026-08-18+0.40
2026-08-17-5.69
2026-08-16-0.61
2026-08-15+2.25
2026-08-14-2.75
2026-08-13-3.47
2026-08-12-1.79
2026-08-11-2.02
2026-08-10+1.08
2026-08-09+2.46
2026-08-08-0.16
2026-08-07-2.15
2026-08-06-1.19
2026-08-05+0.21
2026-08-04-1.73
2026-08-03-6.65
2026-08-02-0.98
2026-08-01-2.46

Error distribution

Distribution of the signed daily error in °F for NCEP GFS at KBOS, lead day 0-10 to -9 °F: 0 days-9 to -8 °F: 0 days-8 to -7 °F: 0 days-7 to -6 °F: 1 day-6 to -5 °F: 1 day-5 to -4 °F: 1 day-4 to -3 °F: 1 day-3 to -2 °F: 6 days-2 to -1 °F: 5 days-1 to 0 °F: 3 days0 to 1 °F: 3 days1 to 2 °F: 1 day2 to 3 °F: 6 days3 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| 2.22 · P90 |e| 3.86 °F-100+10 °Fn = 29 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
-7.00-6.001
-6.00-5.001
-5.00-4.001
-4.00-3.001
-3.00-2.006
-2.00-1.005
-1.00+0.003
+0.00+1.003
+1.00+2.001
+2.00+3.006
+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
2026-08292.22 -0.80

Availability

ModelScored period DaysCoverage
NCEP GFS2026-08-01 → 2026-08-30 29
NCEP GFS2026-08-01 → 2026-08-30 29

Compared with other models

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

Other modelCommon days MAE difference °FDistinguishable
ECMWF AIFS Single 29 -1.03 [-1.74, -0.43] yes
Aurora (GFS init) 2 -2.45 [-5.59, 0.69] no
Aurora (IFS init) 2 -1.35 [-4.26, 1.56] no
FourCastNet v2 (GFS init) 2 -3.28 [-8.87, 2.30] no
FourCastNet v2 (IFS init) 2 -2.82 [-7.86, 2.23] no
GraphCast (GFS init) 2 -2.89 [-6.62, 0.85] no
GraphCast (IFS init) 27 -0.80 [-1.49, -0.23] yes
ECMWF IFS HRES 23 +0.09 [-0.37, 0.40] no
Pangu-Weather (GFS init) 2 -1.16 [-3.67, 1.35] no
Pangu-Weather (IFS init) 2 -1.06 [-2.91, 0.79] no

Cite this page

ShortCastCheck, KBOS gfs lead 0, methodology v0.2, accessed 2026-08-31, https://castcheck.zifanzhang.com/station/KBOS/model/gfs/lead/0/

LongCastCheck (2026). Station-level verification of raw weather-model 2 m temperature forecasts: KBOS (Boston Logan), model gfs, lead day 0. Methodology version 0.2, schema version 0.1, data through 2026-08-30. Accessed 2026-08-31. https://castcheck.zifanzhang.com/station/KBOS/model/gfs/lead/0/

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

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