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 7

KBOS · gfs · 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, 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
tmax00Zbilinear30d22 1 QC5.49 [4.00, 7.01]5.49-0.02 [-2.46, 2.35]6.79 [5.13, 8.23]14% [5%, 24%]23%32%+0.22+0.232026-08-08 → 2026-08-30
tmax00Zbilinear90d22 1 QC5.49 [3.87, 7.22]5.49-0.02 [-2.58, 2.65]6.79 [5.01, 8.40]14% [0%, 25%]23%32%+0.22+0.232026-08-08 → 2026-08-30
tmax00Zbilinear365d22 1 QC5.49 [3.86, 7.28]5.49-0.02 [-2.76, 2.80]6.79 [4.96, 8.51]14% [0%, 25%]23%32%+0.22+0.232026-08-08 → 2026-08-30
tmax00Zbilinearall22 1 QC5.49 [3.97, 7.37]5.49-0.02 [-3.01, 2.66]6.79 [5.02, 8.56]14% [0%, 25%]23%32%+0.22+0.232026-08-08 → 2026-08-30
tmax00Znearest30d22 1 QC5.72 [4.42, 6.94]5.52-0.75 [-3.14, 1.64]6.69 [5.17, 7.99]0% [0%, 0%]14%23%+0.19+0.232026-08-08 → 2026-08-30
tmax00Znearest90d22 1 QC5.72 [4.29, 7.12]5.52-0.75 [-3.20, 1.97]6.69 [5.02, 8.13]0% [0%, 0%]14%23%+0.19+0.232026-08-08 → 2026-08-30
tmax00Znearest365d22 1 QC5.72 [4.24, 7.13]5.52-0.75 [-3.40, 2.16]6.69 [4.88, 8.19]0% [0%, 0%]14%23%+0.19+0.232026-08-08 → 2026-08-30
tmax00Znearestall22 1 QC5.72 [4.39, 7.22]5.52-0.75 [-3.75, 2.13]6.69 [5.05, 8.22]0% [0%, 0%]14%23%+0.19+0.232026-08-08 → 2026-08-30
tmax12Zbilinear30d22 1 QC4.40 [3.70, 5.38]4.40-0.26 [-2.52, 2.21]5.45 [4.58, 6.42]14% [5%, 22%]27%45%+0.38+0.382026-08-08 → 2026-08-30
tmax12Zbilinear90d22 1 QC4.40 [3.68, 5.58]4.40-0.26 [-2.59, 2.94]5.45 [4.45, 6.56]14% [0%, 23%]27%45%+0.38+0.382026-08-08 → 2026-08-30
tmax12Zbilinear365d22 1 QC4.40 [3.64, 5.54]4.40-0.26 [-2.73, 2.73]5.45 [4.45, 6.59]14% [0%, 23%]27%45%+0.38+0.382026-08-08 → 2026-08-30
tmax12Zbilinearall22 1 QC4.40 [3.66, 5.55]4.40-0.26 [-3.04, 2.83]5.45 [4.45, 6.60]14% [0%, 23%]27%45%+0.38+0.382026-08-08 → 2026-08-30
tmax12Znearest30d22 1 QC4.37 [3.47, 5.38]4.37-0.90 [-3.14, 1.53]5.44 [4.50, 6.33]14% [0%, 30%]27%50%+0.38+0.392026-08-08 → 2026-08-30
tmax12Znearest90d22 1 QC4.37 [3.33, 5.54]4.37-0.90 [-3.18, 2.12]5.44 [4.33, 6.47]14% [0%, 30%]27%50%+0.38+0.392026-08-08 → 2026-08-30
tmax12Znearest365d22 1 QC4.37 [3.28, 5.58]4.37-0.90 [-3.32, 1.98]5.44 [4.35, 6.44]14% [0%, 33%]27%50%+0.38+0.392026-08-08 → 2026-08-30
tmax12Znearestall22 1 QC4.37 [3.29, 5.63]4.37-0.90 [-3.63, 2.07]5.44 [4.41, 6.54]14% [0%, 33%]27%50%+0.38+0.392026-08-08 → 2026-08-30
tmin00Zbilinear30d22 1 QC2.45 [2.09, 3.03]2.49-0.27 [-1.43, 1.06]3.10 [2.58, 3.69]23% [6%, 39%]50%68%+0.36+0.312026-08-08 → 2026-08-30
tmin00Zbilinear90d22 1 QC2.45 [2.08, 3.18]2.49-0.27 [-1.57, 1.55]3.10 [2.58, 3.80]23% [0%, 39%]50%68%+0.36+0.312026-08-08 → 2026-08-30
tmin00Zbilinear365d22 1 QC2.45 [2.07, 3.06]2.49-0.27 [-1.60, 1.42]3.10 [2.49, 3.81]23% [0%, 41%]50%68%+0.36+0.312026-08-08 → 2026-08-30
tmin00Zbilinearall22 1 QC2.45 [2.05, 3.32]2.49-0.27 [-1.66, 1.39]3.10 [2.54, 3.83]23% [0%, 41%]50%68%+0.36+0.312026-08-08 → 2026-08-30
tmin00Znearest30d22 1 QC2.42 [2.11, 2.84]2.40+0.17 [-0.77, 1.25]2.90 [2.42, 3.40]18% [6%, 30%]41%77%+0.37+0.332026-08-08 → 2026-08-30
tmin00Znearest90d22 1 QC2.42 [2.12, 2.97]2.40+0.17 [-0.91, 1.60]2.90 [2.42, 3.46]18% [0%, 29%]41%77%+0.37+0.332026-08-08 → 2026-08-30
tmin00Znearest365d22 1 QC2.42 [2.12, 2.93]2.40+0.17 [-0.90, 1.50]2.90 [2.38, 3.48]18% [0%, 30%]41%77%+0.37+0.332026-08-08 → 2026-08-30
tmin00Znearestall22 1 QC2.42 [2.11, 3.01]2.40+0.17 [-0.94, 1.53]2.90 [2.40, 3.49]18% [0%, 30%]41%77%+0.37+0.332026-08-08 → 2026-08-30
tmin12Zbilinear30d22 1 QC2.48 [2.04, 2.95]2.45-0.38 [-1.67, 1.48]2.86 [2.42, 3.26]23% [7%, 36%]36%55%+0.35+0.322026-08-08 → 2026-08-30
tmin12Zbilinear90d22 1 QC2.48 [2.01, 3.05]2.45-0.38 [-1.78, 2.17]2.86 [2.39, 3.33]23% [0%, 36%]36%55%+0.35+0.322026-08-08 → 2026-08-30
tmin12Zbilinear365d22 1 QC2.48 [1.99, 3.02]2.45-0.38 [-1.74, 1.96]2.86 [2.39, 3.29]23% [0%, 37%]36%55%+0.35+0.322026-08-08 → 2026-08-30
tmin12Zbilinearall22 1 QC2.48 [1.96, 2.99]2.45-0.38 [-1.81, 1.94]2.86 [2.34, 3.25]23% [0%, 36%]36%55%+0.35+0.322026-08-08 → 2026-08-30
tmin12Znearest30d22 1 QC2.09 [1.75, 2.57]2.09-0.04 [-1.09, 1.45]2.44 [2.05, 2.89]23% [10%, 33%]55%68%+0.45+0.422026-08-08 → 2026-08-30
tmin12Znearest90d22 1 QC2.09 [1.72, 2.69]2.09-0.04 [-1.20, 2.03]2.44 [2.01, 3.01]23% [4%, 33%]55%68%+0.45+0.422026-08-08 → 2026-08-30
tmin12Znearest365d22 1 QC2.09 [1.72, 2.64]2.09-0.04 [-1.17, 1.85]2.44 [1.97, 2.95]23% [0%, 33%]55%68%+0.45+0.422026-08-08 → 2026-08-30
tmin12Znearestall22 1 QC2.09 [1.68, 2.61]2.09-0.04 [-1.22, 1.81]2.44 [1.91, 2.94]23% [0%, 34%]55%68%+0.45+0.422026-08-08 → 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 NCEP GFS at KBOS, lead day 7, 00Z bilinear tmax+20+100-10-202026-08-08: -0.45 °F2026-08-09: +2.76 °F2026-08-10: +10.93 °F2026-08-11: -1.44 °F2026-08-12: -3.87 °F2026-08-13: -3.71 °F2026-08-14: -12.09 °F2026-08-15: +3.93 °F2026-08-16: -2.99 °F2026-08-17: -1.42 °F2026-08-18: -0.93 °F2026-08-19: -5.37 °F2026-08-20: -3.91 °F2026-08-21: +8.29 °F2026-08-22: +9.96 °F2026-08-23: +15.21 °F2026-08-24: -8.61 °F2026-08-25: -0.86 °F2026-08-26: +4.24 °F2026-08-27: -9.71 °F2026-08-29: +4.84 °F2026-08-30: -5.3 °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
2026-08-30-5.30
2026-08-29+4.84
2026-08-28—
2026-08-27-9.71
2026-08-26+4.24
2026-08-25-0.86
2026-08-24-8.61
2026-08-23+15.21
2026-08-22+9.96
2026-08-21+8.29
2026-08-20-3.91
2026-08-19-5.37
2026-08-18-0.93
2026-08-17-1.42
2026-08-16-2.99
2026-08-15+3.93
2026-08-14-12.09
2026-08-13-3.71
2026-08-12-3.87
2026-08-11-1.44
2026-08-10+10.93
2026-08-09+2.76
2026-08-08-0.45

Error distribution

Distribution of the signed daily error in °F for NCEP GFS 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: 1 day-12 to -10 °F: 0 days-10 to -8 °F: 2 days-8 to -6 °F: 0 days-6 to -4 °F: 2 days-4 to -2 °F: 4 days-2 to 0 °F: 5 days0 to 2 °F: 0 days2 to 4 °F: 2 days4 to 6 °F: 2 days6 to 8 °F: 0 days8 to 10 °F: 2 days10 to 12 °F: 1 day12 to 14 °F: 0 days14 to 16 °F: 1 day16 to 18 °F: 0 days18 to 20 °F: 0 daysdashed: P50 |e| 4.08 · P90 |e| 10.83 °F-200+20 °Fn = 22 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
-14.00-12.001
-12.00-10.000
-10.00-8.002
-8.00-6.000
-6.00-4.002
-4.00-2.004
-2.00+0.005
+0.00+2.000
+2.00+4.002
+4.00+6.002
+6.00+8.000
+8.00+10.002
+10.00+12.001
+12.00+14.000
+14.00+16.001
+16.00+18.000
+18.00+20.000

Month by month

00Z bilinear daily maximum, newest first.

Monthn MAE °FBias °F
2026-08225.49 -0.02

Availability

ModelScored period DaysCoverage
NCEP GFS2026-08-08 → 2026-08-30 22
NCEP GFS2026-08-08 → 2026-08-30 22
NCEP GFS2026-08-08 → 2026-08-30 22
NCEP GFS2026-08-08 → 2026-08-30 22

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 22 +0.62 [-1.74, 2.24] no
GraphCast (IFS init) 22 +0.97 [-0.72, 2.23] no
ECMWF IFS HRES 17 +1.40 [-3.51, 3.34] no
Persistence (baseline) 22 -1.55 [-4.08, 0.43] no

Cite this page

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

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