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 · NCEP GFS · lead day 5

KBOS · gfs · 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, 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
tmax00Zbilinear30d24 1 QC4.21 [3.34, 5.10]4.10-0.89 [-1.86, 0.20]5.13 [4.26, 5.75]21% [7%, 32%]29%42%+0.39+0.382026-08-06 → 2026-08-30
tmax00Zbilinear90d24 1 QC4.21 [3.21, 5.19]4.10-0.89 [-1.96, 0.36]5.13 [4.18, 5.81]21% [6%, 33%]29%42%+0.39+0.382026-08-06 → 2026-08-30
tmax00Zbilinear365d24 1 QC4.21 [3.20, 5.27]4.10-0.89 [-1.98, 0.29]5.13 [4.06, 5.83]21% [0%, 33%]29%42%+0.39+0.382026-08-06 → 2026-08-30
tmax00Zbilinearall24 1 QC4.21 [3.16, 5.25]4.10-0.89 [-2.04, 0.33]5.13 [4.12, 5.83]21% [0%, 33%]29%42%+0.39+0.382026-08-06 → 2026-08-30
tmax00Znearest30d24 1 QC4.27 [3.52, 5.04]3.96-1.32 [-2.19, -0.40]5.02 [4.22, 5.62]12% [0%, 25%]21%38%+0.38+0.402026-08-06 → 2026-08-30
tmax00Znearest90d24 1 QC4.27 [3.46, 5.15]3.96-1.32 [-2.29, -0.26]5.02 [4.13, 5.71]12% [0%, 26%]21%38%+0.38+0.402026-08-06 → 2026-08-30
tmax00Znearest365d24 1 QC4.27 [3.40, 5.14]3.96-1.32 [-2.29, -0.27]5.02 [4.10, 5.70]12% [0%, 25%]21%38%+0.38+0.402026-08-06 → 2026-08-30
tmax00Znearestall24 1 QC4.27 [3.41, 5.19]3.96-1.32 [-2.40, -0.39]5.02 [4.11, 5.75]12% [0%, 27%]21%38%+0.38+0.402026-08-06 → 2026-08-30
tmax12Zbilinear30d24 1 QC3.59 [2.74, 4.30]3.61-0.76 [-2.31, 1.55]4.65 [3.56, 5.42]25% [8%, 42%]38%42%+0.48+0.462026-08-06 → 2026-08-30
tmax12Zbilinear90d24 1 QC3.59 [2.55, 4.36]3.61-0.76 [-2.31, 2.59]4.65 [3.27, 5.44]25% [6%, 46%]38%42%+0.48+0.462026-08-06 → 2026-08-30
tmax12Zbilinear365d24 1 QC3.59 [2.56, 4.41]3.61-0.76 [-2.24, 2.54]4.65 [3.11, 5.52]25% [0%, 45%]38%42%+0.48+0.462026-08-06 → 2026-08-30
tmax12Zbilinearall24 1 QC3.59 [2.50, 4.35]3.61-0.76 [-2.36, 2.54]4.65 [3.21, 5.45]25% [6%, 45%]38%42%+0.48+0.462026-08-06 → 2026-08-30
tmax12Znearest30d24 1 QC3.61 [2.72, 4.38]3.57-1.31 [-2.95, 0.97]4.69 [3.67, 5.46]21% [8%, 35%]38%50%+0.47+0.462026-08-06 → 2026-08-30
tmax12Znearest90d24 1 QC3.61 [2.53, 4.38]3.57-1.31 [-3.05, 1.96]4.69 [3.49, 5.50]21% [7%, 38%]38%50%+0.47+0.462026-08-06 → 2026-08-30
tmax12Znearest365d24 1 QC3.61 [2.54, 4.46]3.57-1.31 [-2.96, 1.81]4.69 [3.43, 5.62]21% [7%, 37%]38%50%+0.47+0.462026-08-06 → 2026-08-30
tmax12Znearestall24 1 QC3.61 [2.50, 4.39]3.57-1.31 [-3.09, 1.87]4.69 [3.53, 5.53]21% [5%, 37%]38%50%+0.47+0.462026-08-06 → 2026-08-30
tmin00Zbilinear30d24 1 QC3.02 [2.24, 3.86]2.86-1.13 [-2.11, -0.25]3.59 [2.74, 4.39]21% [4%, 42%]38%50%+0.10+0.112026-08-06 → 2026-08-30
tmin00Zbilinear90d24 1 QC3.02 [2.16, 4.00]2.86-1.13 [-2.13, -0.17]3.59 [2.61, 4.47]21% [0%, 44%]38%50%+0.10+0.112026-08-06 → 2026-08-30
tmin00Zbilinear365d24 1 QC3.02 [2.09, 4.16]2.86-1.13 [-2.16, -0.07]3.59 [2.56, 4.60]21% [0%, 45%]38%50%+0.10+0.112026-08-06 → 2026-08-30
tmin00Zbilinearall24 1 QC3.02 [2.11, 4.05]2.86-1.13 [-2.24, -0.21]3.59 [2.54, 4.53]21% [0%, 44%]38%50%+0.10+0.112026-08-06 → 2026-08-30
tmin00Znearest30d24 1 QC2.73 [1.88, 3.65]2.70-0.62 [-1.64, 0.37]3.32 [2.49, 4.09]25% [4%, 52%]42%58%+0.18+0.162026-08-06 → 2026-08-30
tmin00Znearest90d24 1 QC2.73 [1.80, 3.70]2.70-0.62 [-1.72, 0.37]3.32 [2.35, 4.18]25% [0%, 56%]42%58%+0.18+0.162026-08-06 → 2026-08-30
tmin00Znearest365d24 1 QC2.73 [1.73, 3.85]2.70-0.62 [-1.72, 0.49]3.32 [2.32, 4.27]25% [0%, 57%]42%58%+0.18+0.162026-08-06 → 2026-08-30
tmin00Znearestall24 1 QC2.73 [1.73, 3.78]2.70-0.62 [-1.86, 0.34]3.32 [2.26, 4.22]25% [0%, 56%]42%58%+0.18+0.162026-08-06 → 2026-08-30
tmin12Zbilinear30d24 1 QC2.49 [1.77, 3.10]2.20-1.76 [-2.49, -0.99]3.37 [2.32, 3.97]29% [17%, 43%]58%75%+0.25+0.312026-08-06 → 2026-08-30
tmin12Zbilinear90d24 1 QC2.49 [1.57, 3.16]2.20-1.76 [-2.58, -0.95]3.37 [2.01, 4.02]29% [15%, 46%]58%75%+0.25+0.312026-08-06 → 2026-08-30
tmin12Zbilinear365d24 1 QC2.49 [1.56, 3.14]2.20-1.76 [-2.63, -0.87]3.37 [2.01, 4.01]29% [15%, 45%]58%75%+0.25+0.312026-08-06 → 2026-08-30
tmin12Zbilinearall24 1 QC2.49 [1.65, 3.15]2.20-1.76 [-2.65, -0.96]3.37 [2.10, 4.02]29% [14%, 50%]58%75%+0.25+0.312026-08-06 → 2026-08-30
tmin12Znearest30d24 1 QC2.50 [1.86, 2.99]2.21-1.36 [-2.13, -0.55]3.14 [2.27, 3.67]25% [14%, 40%]46%75%+0.25+0.312026-08-06 → 2026-08-30
tmin12Znearest90d24 1 QC2.50 [1.68, 3.04]2.21-1.36 [-2.15, -0.55]3.14 [2.05, 3.72]25% [13%, 45%]46%75%+0.25+0.312026-08-06 → 2026-08-30
tmin12Znearest365d24 1 QC2.50 [1.72, 3.00]2.21-1.36 [-2.23, -0.43]3.14 [2.05, 3.70]25% [14%, 44%]46%75%+0.25+0.312026-08-06 → 2026-08-30
tmin12Znearestall24 1 QC2.50 [1.73, 3.02]2.21-1.36 [-2.27, -0.59]3.14 [2.09, 3.70]25% [14%, 45%]46%75%+0.25+0.312026-08-06 → 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 NCEP GFS at KBOS, lead day 5, 00Z bilinear tmax+10+50-5-102026-08-06: +3.75 °F2026-08-07: -2.28 °F2026-08-08: -0.52 °F2026-08-09: +0.82 °F2026-08-10: +5.14 °F2026-08-11: -9.57 °F2026-08-12: +3.13 °F2026-08-13: -2.73 °F2026-08-14: -7.82 °F2026-08-15: +0.52 °F2026-08-16: -0.05 °F2026-08-17: +7.51 °F2026-08-18: -1.79 °F2026-08-19: -1.76 °F2026-08-20: -9.54 °F2026-08-21: -2.52 °F2026-08-22: +7.39 °F2026-08-23: -3.31 °F2026-08-24: -4.56 °F2026-08-25: -6.58 °F2026-08-26: +6.97 °F2026-08-27: -0.7 °F2026-08-29: +4.6 °F2026-08-30: -7.4 °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
2026-08-30-7.40
2026-08-29+4.60
2026-08-28—
2026-08-27-0.70
2026-08-26+6.97
2026-08-25-6.58
2026-08-24-4.56
2026-08-23-3.31
2026-08-22+7.39
2026-08-21-2.52
2026-08-20-9.54
2026-08-19-1.76
2026-08-18-1.79
2026-08-17+7.51
2026-08-16-0.05
2026-08-15+0.52
2026-08-14-7.82
2026-08-13-2.73
2026-08-12+3.13
2026-08-11-9.57
2026-08-10+5.14
2026-08-09+0.82
2026-08-08-0.52
2026-08-07-2.28
2026-08-06+3.75

Error distribution

Distribution of the signed daily error in °F for NCEP GFS at KBOS, lead day 5-10 to -9 °F: 2 days-9 to -8 °F: 0 days-8 to -7 °F: 2 days-7 to -6 °F: 1 day-6 to -5 °F: 0 days-5 to -4 °F: 1 day-4 to -3 °F: 1 day-3 to -2 °F: 3 days-2 to -1 °F: 2 days-1 to 0 °F: 3 days0 to 1 °F: 2 days1 to 2 °F: 0 days2 to 3 °F: 0 days3 to 4 °F: 2 days4 to 5 °F: 1 day5 to 6 °F: 1 day6 to 7 °F: 1 day7 to 8 °F: 2 days8 to 9 °F: 0 days9 to 10 °F: 0 daysdashed: P50 |e| 3.53 · P90 |e| 7.73 °F-100+10 °Fn = 24 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
-10.00-9.002
-9.00-8.000
-8.00-7.002
-7.00-6.001
-6.00-5.000
-5.00-4.001
-4.00-3.001
-3.00-2.003
-2.00-1.002
-1.00+0.003
+0.00+1.002
+1.00+2.000
+2.00+3.000
+3.00+4.002
+4.00+5.001
+5.00+6.001
+6.00+7.001
+7.00+8.002
+8.00+9.000
+9.00+10.000

Month by month

00Z bilinear daily maximum, newest first.

Monthn MAE °FBias °F
2026-08244.21 -0.89

Availability

ModelScored period DaysCoverage
NCEP GFS2026-08-06 → 2026-08-30 24
NCEP GFS2026-08-06 → 2026-08-30 24
NCEP GFS2026-08-06 → 2026-08-30 24
NCEP GFS2026-08-06 → 2026-08-30 24

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 24 -0.42 [-1.58, 1.01] no
GraphCast (IFS init) 24 +0.04 [-1.08, 1.12] no
ECMWF IFS HRES 17 +0.64 [-1.30, 1.84] no
Persistence (baseline) 24 -2.67 [-4.06, -1.34] yes

Cite this page

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

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