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 1

KBOS · gfs · lead 1

Target day = initialization date + 1 day. 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
tmax00Zbilinear30d28 1 QC2.85 [2.01, 3.87]2.86-0.93 [-2.05, 0.17]3.83 [2.73, 5.00]36% [25%, 48%]43%57%+0.41+0.422026-08-02 → 2026-08-30
tmax00Zbilinear90d28 1 QC2.85 [1.93, 3.93]2.86-0.93 [-2.20, 0.33]3.83 [2.60, 5.04]36% [22%, 50%]43%57%+0.41+0.422026-08-02 → 2026-08-30
tmax00Zbilinear365d28 1 QC2.85 [1.83, 3.93]2.86-0.93 [-2.21, 0.44]3.83 [2.55, 5.00]36% [21%, 55%]43%57%+0.41+0.422026-08-02 → 2026-08-30
tmax00Zbilinearall28 1 QC2.85 [1.92, 3.93]2.86-0.93 [-2.23, 0.42]3.83 [2.57, 5.03]36% [21%, 50%]43%57%+0.41+0.422026-08-02 → 2026-08-30
tmax00Znearest30d28 1 QC3.07 [2.29, 3.98]2.85-1.42 [-2.47, -0.35]3.94 [2.96, 5.01]18% [4%, 33%]43%50%+0.38+0.422026-08-02 → 2026-08-30
tmax00Znearest90d28 1 QC3.07 [2.18, 4.04]2.85-1.42 [-2.63, -0.15]3.94 [2.87, 5.05]18% [0%, 36%]43%50%+0.38+0.422026-08-02 → 2026-08-30
tmax00Znearest365d28 1 QC3.07 [2.11, 4.04]2.85-1.42 [-2.62, -0.14]3.94 [2.76, 5.01]18% [0%, 36%]43%50%+0.38+0.422026-08-02 → 2026-08-30
tmax00Znearestall28 1 QC3.07 [2.19, 4.02]2.85-1.42 [-2.66, -0.15]3.94 [2.83, 5.06]18% [0%, 36%]43%50%+0.38+0.422026-08-02 → 2026-08-30
tmax12Zbilinear30d28 1 QC2.22 [1.64, 2.75]2.25-0.29 [-1.11, 0.41]2.92 [2.37, 3.36]36% [18%, 53%]50%71%+0.56+0.562026-08-02 → 2026-08-30
tmax12Zbilinear90d28 1 QC2.22 [1.54, 2.84]2.25-0.29 [-1.39, 0.62]2.92 [2.07, 3.49]36% [17%, 55%]50%71%+0.56+0.562026-08-02 → 2026-08-30
tmax12Zbilinear365d28 1 QC2.22 [1.54, 2.86]2.25-0.29 [-1.27, 0.64]2.92 [1.95, 3.52]36% [15%, 55%]50%71%+0.56+0.562026-08-02 → 2026-08-30
tmax12Zbilinearall28 1 QC2.22 [1.54, 2.94]2.25-0.29 [-1.60, 0.60]2.92 [2.14, 3.60]36% [14%, 55%]50%71%+0.56+0.562026-08-02 → 2026-08-30
tmax12Znearest30d28 1 QC2.20 [1.73, 2.59]2.08-0.75 [-1.51, -0.07]2.77 [2.22, 3.26]25% [13%, 38%]57%75%+0.55+0.592026-08-02 → 2026-08-30
tmax12Znearest90d28 1 QC2.20 [1.53, 2.75]2.08-0.75 [-1.82, 0.09]2.77 [1.94, 3.48]25% [12%, 44%]57%75%+0.55+0.592026-08-02 → 2026-08-30
tmax12Znearest365d28 1 QC2.20 [1.45, 2.77]2.08-0.75 [-1.71, 0.10]2.77 [1.81, 3.43]25% [12%, 50%]57%75%+0.55+0.592026-08-02 → 2026-08-30
tmax12Znearestall28 1 QC2.20 [1.53, 2.80]2.08-0.75 [-1.99, 0.03]2.77 [1.97, 3.59]25% [12%, 44%]57%75%+0.55+0.592026-08-02 → 2026-08-30
tmin00Zbilinear30d28 1 QC1.59 [1.17, 2.04]1.56-0.69 [-1.22, -0.11]1.91 [1.54, 2.28]32% [10%, 57%]64%89%+0.17+0.182026-08-02 → 2026-08-30
tmin00Zbilinear90d28 1 QC1.59 [1.03, 2.12]1.56-0.69 [-1.37, -0.07]1.91 [1.36, 2.38]32% [8%, 60%]64%89%+0.17+0.182026-08-02 → 2026-08-30
tmin00Zbilinear365d28 1 QC1.59 [1.04, 2.26]1.56-0.69 [-1.46, -0.04]1.91 [1.34, 2.50]32% [5%, 62%]64%89%+0.17+0.182026-08-02 → 2026-08-30
tmin00Zbilinearall28 1 QC1.59 [1.01, 2.16]1.56-0.69 [-1.41, -0.12]1.91 [1.34, 2.42]32% [6%, 61%]64%89%+0.17+0.182026-08-02 → 2026-08-30
tmin00Znearest30d28 1 QC1.56 [1.15, 1.98]1.55-0.38 [-0.88, 0.19]1.79 [1.44, 2.12]29% [7%, 50%]71%93%+0.18+0.182026-08-02 → 2026-08-30
tmin00Znearest90d28 1 QC1.56 [1.09, 2.02]1.55-0.38 [-1.02, 0.21]1.79 [1.36, 2.15]29% [7%, 51%]71%93%+0.18+0.182026-08-02 → 2026-08-30
tmin00Znearest365d28 1 QC1.56 [1.06, 2.12]1.55-0.38 [-1.08, 0.26]1.79 [1.34, 2.24]29% [4%, 54%]71%93%+0.18+0.182026-08-02 → 2026-08-30
tmin00Znearestall28 1 QC1.56 [1.05, 2.08]1.55-0.38 [-1.05, 0.19]1.79 [1.34, 2.23]29% [5%, 53%]71%93%+0.18+0.182026-08-02 → 2026-08-30
tmin12Zbilinear30d28 1 QC1.56 [1.23, 1.93]1.35-0.64 [-1.16, -0.10]1.87 [1.45, 2.30]39% [26%, 53%]75%82%+0.17+0.272026-08-02 → 2026-08-30
tmin12Zbilinear90d28 1 QC1.56 [1.25, 1.97]1.35-0.64 [-1.21, -0.17]1.87 [1.46, 2.31]39% [23%, 54%]75%82%+0.17+0.272026-08-02 → 2026-08-30
tmin12Zbilinear365d28 1 QC1.56 [1.21, 2.04]1.35-0.64 [-1.25, -0.05]1.87 [1.42, 2.36]39% [22%, 54%]75%82%+0.17+0.272026-08-02 → 2026-08-30
tmin12Zbilinearall28 1 QC1.56 [1.21, 1.98]1.35-0.64 [-1.28, -0.12]1.87 [1.40, 2.36]39% [23%, 55%]75%82%+0.17+0.272026-08-02 → 2026-08-30
tmin12Znearest30d28 1 QC1.51 [1.09, 1.88]1.46-0.26 [-0.84, 0.46]1.94 [1.38, 2.36]54% [39%, 71%]68%86%+0.18+0.212026-08-02 → 2026-08-30
tmin12Znearest90d28 1 QC1.51 [1.05, 1.92]1.46-0.26 [-0.91, 0.39]1.94 [1.31, 2.39]54% [39%, 73%]68%86%+0.18+0.212026-08-02 → 2026-08-30
tmin12Znearest365d28 1 QC1.51 [1.04, 1.94]1.46-0.26 [-1.00, 0.53]1.94 [1.31, 2.42]54% [38%, 75%]68%86%+0.18+0.212026-08-02 → 2026-08-30
tmin12Znearestall28 1 QC1.51 [1.05, 1.92]1.46-0.26 [-0.98, 0.37]1.94 [1.30, 2.40]54% [38%, 75%]68%86%+0.18+0.212026-08-02 → 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 1, 00Z bilinear tmax+20+100-10-202026-08-02: -1.23 °F2026-08-03: -6.86 °F2026-08-04: -1.96 °F2026-08-05: +0.34 °F2026-08-06: +3.56 °F2026-08-07: +0.24 °F2026-08-08: -3.09 °F2026-08-09: +2.28 °F2026-08-10: +3.92 °F2026-08-11: +0.43 °F2026-08-12: +0.39 °F2026-08-13: -0.03 °F2026-08-14: -2.68 °F2026-08-15: +4.25 °F2026-08-16: +0.42 °F2026-08-17: -6.27 °F2026-08-18: -2.61 °F2026-08-19: -0.91 °F2026-08-20: -10.88 °F2026-08-21: +5.94 °F2026-08-22: -4.35 °F2026-08-23: -0.1 °F2026-08-24: -2.09 °F2026-08-25: -4.16 °F2026-08-26: +4.72 °F2026-08-27: -5.03 °F2026-08-29: -0.69 °F2026-08-30: +0.45 °F2026-08-022026-08-30°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 (29 days, newest first) · download CSV
Climatological dayError °F
2026-08-30+0.45
2026-08-29-0.69
2026-08-28—
2026-08-27-5.03
2026-08-26+4.72
2026-08-25-4.16
2026-08-24-2.09
2026-08-23-0.10
2026-08-22-4.35
2026-08-21+5.94
2026-08-20-10.88
2026-08-19-0.91
2026-08-18-2.61
2026-08-17-6.27
2026-08-16+0.42
2026-08-15+4.25
2026-08-14-2.68
2026-08-13-0.03
2026-08-12+0.39
2026-08-11+0.43
2026-08-10+3.92
2026-08-09+2.28
2026-08-08-3.09
2026-08-07+0.24
2026-08-06+3.56
2026-08-05+0.34
2026-08-04-1.96
2026-08-03-6.86
2026-08-02-1.23

Error distribution

Distribution of the signed daily error in °F for NCEP GFS at KBOS, lead day 1-20 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: 1 day-10 to -8 °F: 0 days-8 to -6 °F: 2 days-6 to -4 °F: 3 days-4 to -2 °F: 4 days-2 to 0 °F: 6 days0 to 2 °F: 6 days2 to 4 °F: 3 days4 to 6 °F: 3 days6 to 8 °F: 0 days8 to 10 °F: 0 days10 to 12 °F: 0 days12 to 14 °F: 0 days14 to 16 °F: 0 days16 to 18 °F: 0 days18 to 20 °F: 0 daysdashed: P50 |e| 2.44 · P90 |e| 6.04 °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
-12.00-10.001
-10.00-8.000
-8.00-6.002
-6.00-4.003
-4.00-2.004
-2.00+0.006
+0.00+2.006
+2.00+4.003
+4.00+6.003
+6.00+8.000
+8.00+10.000
+10.00+12.000
+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
2026-08282.85 -0.93

Availability

ModelScored period DaysCoverage
NCEP GFS2026-08-02 → 2026-08-30 28
NCEP GFS2026-08-02 → 2026-08-30 28
NCEP GFS2026-08-02 → 2026-08-30 28
NCEP GFS2026-08-02 → 2026-08-30 28

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 28 -0.53 [-1.54, 0.65] no
Aurora (GFS init) 1 -5.09 [-5.09, -5.09] yes
Aurora (IFS init) 2 -2.44 [-4.44, -0.44] yes
FourCastNet v2 (GFS init) 1 -6.22 [-6.22, -6.22] yes
FourCastNet v2 (IFS init) 2 -4.21 [-6.65, -1.78] yes
GraphCast (GFS init) 1 -4.89 [-4.89, -4.89] yes
GraphCast (IFS init) 27 -0.12 [-1.00, 0.89] no
ECMWF IFS HRES 22 +0.50 [-0.26, 1.08] no
Pangu-Weather (GFS init) 1 -3.05 [-3.05, -3.05] yes
Pangu-Weather (IFS init) 2 -2.06 [-2.71, -1.41] yes
Persistence (baseline) 27 -2.07 [-3.49, -1.25] yes

Cite this page

ShortCastCheck, KBOS gfs lead 1, methodology v0.2, accessed 2026-08-31, https://castcheck.zifanzhang.com/station/KBOS/model/gfs/lead/1/

LongCastCheck (2026). Station-level verification of raw weather-model 2 m temperature forecasts: KBOS (Boston Logan), model gfs, lead day 1. 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/1/

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

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