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

All stations (mean of daily station errors) · NCEP GFS · lead day 8

ALL · gfs · lead 8

Target day = initialization date + 8 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, 2 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 2 QC4.34 [3.94, 4.70]1.25-1.57 [-2.00, -1.02]5.69 [5.17, 6.08]16% [12%, 19%]31%45%-0.01-0.022026-08-09 → 2026-08-30
tmax00Zbilinear90d22 2 QC4.34 [3.84, 4.69]1.25-1.57 [-1.96, -0.91]5.69 [5.02, 6.07]16% [12%, 20%]31%45%-0.01-0.022026-08-09 → 2026-08-30
tmax00Zbilinear365d22 2 QC4.34 [3.82, 4.78]1.25-1.57 [-1.97, -0.91]5.69 [5.03, 6.18]16% [11%, 20%]31%45%-0.01-0.022026-08-09 → 2026-08-30
tmax00Zbilinearall22 2 QC4.34 [3.72, 4.75]1.25-1.57 [-2.02, -0.85]5.69 [4.84, 6.12]16% [11%, 20%]31%45%-0.01-0.022026-08-09 → 2026-08-30
tmax00Znearest30d22 2 QC4.51 [4.05, 4.94]1.24-1.54 [-1.99, -0.97]5.83 [5.27, 6.29]13% [9%, 17%]28%41%-0.05-0.012026-08-09 → 2026-08-30
tmax00Znearest90d22 2 QC4.51 [3.93, 4.94]1.24-1.54 [-1.96, -0.84]5.83 [5.08, 6.28]13% [9%, 18%]28%41%-0.05-0.012026-08-09 → 2026-08-30
tmax00Znearest365d22 2 QC4.51 [3.94, 5.07]1.24-1.54 [-1.97, -0.84]5.83 [5.05, 6.40]13% [8%, 18%]28%41%-0.05-0.012026-08-09 → 2026-08-30
tmax00Znearestall22 2 QC4.51 [3.90, 5.02]1.24-1.54 [-2.03, -0.79]5.83 [4.95, 6.31]13% [8%, 18%]28%41%-0.05-0.012026-08-09 → 2026-08-30
tmax12Zbilinear30d22 2 QC4.23 [3.82, 4.63]1.41-1.38 [-1.77, -0.69]5.61 [5.14, 6.07]18% [14%, 23%]32%47%+0.01-0.142026-08-09 → 2026-08-30
tmax12Zbilinear90d22 2 QC4.23 [3.78, 4.63]1.41-1.38 [-1.78, -0.59]5.61 [5.08, 6.08]18% [13%, 24%]32%47%+0.01-0.142026-08-09 → 2026-08-30
tmax12Zbilinear365d22 2 QC4.23 [3.80, 4.71]1.41-1.38 [-1.78, -0.59]5.61 [5.08, 6.20]18% [13%, 24%]32%47%+0.01-0.142026-08-09 → 2026-08-30
tmax12Zbilinearall22 2 QC4.23 [3.77, 4.72]1.41-1.38 [-1.79, -0.34]5.61 [5.04, 6.15]18% [13%, 24%]32%47%+0.01-0.142026-08-09 → 2026-08-30
tmax12Znearest30d22 2 QC4.36 [3.94, 4.75]1.43-1.36 [-1.76, -0.64]5.71 [5.19, 6.22]17% [13%, 21%]31%44%-0.01-0.162026-08-09 → 2026-08-30
tmax12Znearest90d22 2 QC4.36 [3.90, 4.77]1.43-1.36 [-1.77, -0.54]5.71 [5.13, 6.22]17% [13%, 22%]31%44%-0.01-0.162026-08-09 → 2026-08-30
tmax12Znearest365d22 2 QC4.36 [3.90, 4.84]1.43-1.36 [-1.76, -0.52]5.71 [5.12, 6.33]17% [13%, 22%]31%44%-0.01-0.162026-08-09 → 2026-08-30
tmax12Znearestall22 2 QC4.36 [3.90, 4.85]1.43-1.36 [-1.75, -0.28]5.71 [5.12, 6.31]17% [12%, 22%]31%44%-0.01-0.162026-08-09 → 2026-08-30
tmin00Zbilinear30d22 2 QC3.85 [3.54, 4.10]1.09+1.52 [0.68, 2.32]4.85 [4.48, 5.15]17% [14%, 19%]32%49%-0.02+0.082026-08-09 → 2026-08-30
tmin00Zbilinear90d22 2 QC3.85 [3.44, 4.12]1.09+1.52 [0.61, 2.37]4.85 [4.41, 5.17]17% [14%, 19%]32%49%-0.02+0.082026-08-09 → 2026-08-30
tmin00Zbilinear365d22 2 QC3.85 [3.43, 4.13]1.09+1.52 [0.60, 2.41]4.85 [4.41, 5.19]17% [13%, 19%]32%49%-0.02+0.082026-08-09 → 2026-08-30
tmin00Zbilinearall22 2 QC3.85 [3.46, 4.14]1.09+1.52 [0.60, 2.54]4.85 [4.41, 5.19]17% [13%, 19%]32%49%-0.02+0.082026-08-09 → 2026-08-30
tmin00Znearest30d22 2 QC4.03 [3.66, 4.31]1.09+1.59 [0.73, 2.40]5.06 [4.65, 5.37]16% [14%, 20%]29%44%-0.06+0.082026-08-09 → 2026-08-30
tmin00Znearest90d22 2 QC4.03 [3.54, 4.33]1.09+1.59 [0.65, 2.45]5.06 [4.54, 5.38]16% [14%, 21%]29%44%-0.06+0.082026-08-09 → 2026-08-30
tmin00Znearest365d22 2 QC4.03 [3.51, 4.34]1.09+1.59 [0.63, 2.50]5.06 [4.52, 5.39]16% [14%, 21%]29%44%-0.06+0.082026-08-09 → 2026-08-30
tmin00Znearestall22 2 QC4.03 [3.54, 4.35]1.09+1.59 [0.64, 2.64]5.06 [4.54, 5.39]16% [14%, 21%]29%44%-0.06+0.082026-08-09 → 2026-08-30
tmin12Zbilinear30d22 2 QC3.82 [3.56, 4.10]1.31+1.61 [0.70, 2.44]4.94 [4.60, 5.26]19% [16%, 22%]35%50%-0.01-0.102026-08-09 → 2026-08-30
tmin12Zbilinear90d22 2 QC3.82 [3.52, 4.13]1.31+1.61 [0.63, 2.46]4.94 [4.51, 5.29]19% [16%, 22%]35%50%-0.01-0.102026-08-09 → 2026-08-30
tmin12Zbilinear365d22 2 QC3.82 [3.51, 4.16]1.31+1.61 [0.58, 2.48]4.94 [4.51, 5.31]19% [16%, 22%]35%50%-0.01-0.102026-08-09 → 2026-08-30
tmin12Zbilinearall22 2 QC3.82 [3.50, 4.23]1.31+1.61 [0.60, 2.76]4.94 [4.49, 5.37]19% [16%, 22%]35%50%-0.01-0.102026-08-09 → 2026-08-30
tmin12Znearest30d22 2 QC3.96 [3.70, 4.21]1.29+1.65 [0.74, 2.49]5.06 [4.73, 5.37]16% [14%, 19%]32%46%-0.04-0.092026-08-09 → 2026-08-30
tmin12Znearest90d22 2 QC3.96 [3.65, 4.24]1.29+1.65 [0.64, 2.51]5.06 [4.64, 5.40]16% [15%, 19%]32%46%-0.04-0.092026-08-09 → 2026-08-30
tmin12Znearest365d22 2 QC3.96 [3.64, 4.25]1.29+1.65 [0.60, 2.52]5.06 [4.62, 5.42]16% [14%, 19%]32%46%-0.04-0.092026-08-09 → 2026-08-30
tmin12Znearestall22 2 QC3.96 [3.64, 4.33]1.29+1.65 [0.61, 2.78]5.06 [4.61, 5.46]16% [14%, 19%]32%46%-0.04-0.092026-08-09 → 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 ALL, lead day 8, 00Z bilinear tmax+5+2.50-2.5-52026-08-09: -0.25 °F2026-08-10: -0.36 °F2026-08-11: -1.46 °F2026-08-12: -3.95 °F2026-08-13: -3.01 °F2026-08-14: +0.67 °F2026-08-15: -0.99 °F2026-08-16: -0.6 °F2026-08-17: -3.18 °F2026-08-18: -4.56 °F2026-08-19: -2.08 °F2026-08-20: +0.02 °F2026-08-21: -0.77 °F2026-08-22: +0.05 °F2026-08-23: -0.43 °F2026-08-24: -1.17 °F2026-08-25: -2.09 °F2026-08-26: -2.06 °F2026-08-27: -4.97 °F2026-08-28: -2.01 °F2026-08-29: -0.06 °F2026-08-30: -1.25 °F2026-08-092026-08-30°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 (22 days, newest first) · download CSV
Climatological dayError °F
2026-08-30-1.25
2026-08-29-0.06
2026-08-28-2.01
2026-08-27-4.97
2026-08-26-2.06
2026-08-25-2.09
2026-08-24-1.17
2026-08-23-0.43
2026-08-22+0.05
2026-08-21-0.77
2026-08-20+0.02
2026-08-19-2.08
2026-08-18-4.56
2026-08-17-3.18
2026-08-16-0.60
2026-08-15-0.99
2026-08-14+0.67
2026-08-13-3.01
2026-08-12-3.95
2026-08-11-1.46
2026-08-10-0.36
2026-08-09-0.25

Error distribution

Distribution of the signed daily error in °F for NCEP GFS at ALL, lead day 8-5 to -4.5 °F: 2 days-4.5 to -4 °F: 0 days-4 to -3.5 °F: 1 day-3.5 to -3 °F: 2 days-3 to -2.5 °F: 0 days-2.5 to -2 °F: 4 days-2 to -1.5 °F: 0 days-1.5 to -1 °F: 3 days-1 to -0.5 °F: 3 days-0.5 to 0 °F: 4 days0 to 0.5 °F: 2 days0.5 to 1 °F: 1 day1 to 1.5 °F: 0 days1.5 to 2 °F: 0 days2 to 2.5 °F: 0 days2.5 to 3 °F: 0 days3 to 3.5 °F: 0 days3.5 to 4 °F: 0 days4 to 4.5 °F: 0 days4.5 to 5 °F: 0 daysdashed: P50 |e| 1.21 · P90 |e| 3.88 °F-50+5 °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
-5.00-4.502
-4.50-4.000
-4.00-3.501
-3.50-3.002
-3.00-2.500
-2.50-2.004
-2.00-1.500
-1.50-1.003
-1.00-0.503
-0.50+0.004
+0.00+0.502
+0.50+1.001
+1.00+1.500
+1.50+2.000
+2.00+2.500
+2.50+3.000
+3.00+3.500
+3.50+4.000
+4.00+4.500
+4.50+5.000

Month by month

00Z bilinear daily maximum, newest first.

Monthn MAE °FBias °F
2026-08221.64 -1.57

Availability

ModelScored period DaysCoverage
NCEP GFS2026-08-09 → 2026-08-30 22
NCEP GFS2026-08-09 → 2026-08-30 22
NCEP GFS2026-08-09 → 2026-08-30 22
NCEP GFS2026-08-09 → 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 -0.45 [-0.91, 0.09] no
GraphCast (IFS init) 22 -2.07 [-2.70, -1.60] yes
ECMWF IFS HRES 17 +0.05 [-0.54, 0.56] no
Persistence (baseline) 22 +0.04 [-0.43, 0.40] no

Cite this page

ShortCastCheck, ALL gfs lead 8, methodology v0.2, accessed 2026-08-31, https://castcheck.zifanzhang.com/station/ALL/model/gfs/lead/8/

LongCastCheck (2026). Station-level verification of raw weather-model 2 m temperature forecasts: ALL (All stations (mean of daily station errors)), model gfs, lead day 8. Methodology version 0.2, schema version 0.1, data through 2026-08-30. Accessed 2026-08-31. https://castcheck.zifanzhang.com/station/ALL/model/gfs/lead/8/

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