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

All stations (mean of daily station errors) · NCEP GFS · lead day 3

ALL · gfs · lead 3

Target day = initialization date + 3 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
tmax00Zbilinear30d27 2 QC3.20 [3.06, 3.38]0.87-0.81 [-1.40, -0.27]4.12 [3.92, 4.37]21% [19%, 23%]39%56%+0.11+0.312026-08-04 → 2026-08-30
tmax00Zbilinear90d27 2 QC3.20 [3.05, 3.41]0.87-0.81 [-1.46, -0.18]4.12 [3.90, 4.40]21% [19%, 23%]39%56%+0.11+0.312026-08-04 → 2026-08-30
tmax00Zbilinear365d27 2 QC3.20 [3.04, 3.42]0.87-0.81 [-1.53, -0.17]4.12 [3.90, 4.42]21% [19%, 23%]39%56%+0.11+0.312026-08-04 → 2026-08-30
tmax00Zbilinearall27 2 QC3.20 [3.04, 3.44]0.87-0.81 [-1.50, -0.17]4.12 [3.90, 4.43]21% [19%, 23%]39%56%+0.11+0.312026-08-04 → 2026-08-30
tmax00Znearest30d27 2 QC3.46 [3.31, 3.62]0.90-0.76 [-1.36, -0.18]4.39 [4.16, 4.65]18% [16%, 20%]35%52%+0.04+0.282026-08-04 → 2026-08-30
tmax00Znearest90d27 2 QC3.46 [3.31, 3.64]0.90-0.76 [-1.42, -0.06]4.39 [4.15, 4.69]18% [16%, 20%]35%52%+0.04+0.282026-08-04 → 2026-08-30
tmax00Znearest365d27 2 QC3.46 [3.29, 3.64]0.90-0.76 [-1.49, -0.06]4.39 [4.13, 4.66]18% [16%, 20%]35%52%+0.04+0.282026-08-04 → 2026-08-30
tmax00Znearestall27 2 QC3.46 [3.30, 3.65]0.90-0.76 [-1.47, -0.07]4.39 [4.16, 4.70]18% [15%, 20%]35%52%+0.04+0.282026-08-04 → 2026-08-30
tmax12Zbilinear30d27 2 QC3.10 [2.77, 3.43]0.94-0.80 [-1.39, -0.20]4.06 [3.65, 4.48]23% [20%, 26%]44%57%+0.14+0.252026-08-04 → 2026-08-30
tmax12Zbilinear90d27 2 QC3.10 [2.70, 3.51]0.94-0.80 [-1.48, -0.07]4.06 [3.59, 4.54]23% [20%, 27%]44%57%+0.14+0.252026-08-04 → 2026-08-30
tmax12Zbilinear365d27 2 QC3.10 [2.72, 3.55]0.94-0.80 [-1.58, -0.08]4.06 [3.62, 4.61]23% [20%, 27%]44%57%+0.14+0.252026-08-04 → 2026-08-30
tmax12Zbilinearall27 2 QC3.10 [2.70, 3.48]0.94-0.80 [-1.50, -0.09]4.06 [3.59, 4.53]23% [20%, 27%]44%57%+0.14+0.252026-08-04 → 2026-08-30
tmax12Znearest30d27 2 QC3.37 [3.07, 3.69]0.97-0.75 [-1.41, -0.07]4.33 [3.96, 4.76]20% [17%, 23%]39%52%+0.07+0.232026-08-04 → 2026-08-30
tmax12Znearest90d27 2 QC3.37 [3.03, 3.76]0.97-0.75 [-1.53, 0.06]4.33 [3.94, 4.82]20% [16%, 24%]39%52%+0.07+0.232026-08-04 → 2026-08-30
tmax12Znearest365d27 2 QC3.37 [3.02, 3.80]0.97-0.75 [-1.59, 0.04]4.33 [3.94, 4.88]20% [16%, 24%]39%52%+0.07+0.232026-08-04 → 2026-08-30
tmax12Znearestall27 2 QC3.37 [3.03, 3.75]0.97-0.75 [-1.54, 0.05]4.33 [3.93, 4.77]20% [16%, 24%]39%52%+0.07+0.232026-08-04 → 2026-08-30
tmin00Zbilinear30d27 2 QC3.17 [2.90, 3.46]0.58+2.07 [1.67, 2.46]4.05 [3.70, 4.44]21% [19%, 24%]39%56%-0.01+0.442026-08-04 → 2026-08-30
tmin00Zbilinear90d27 2 QC3.17 [2.88, 3.51]0.58+2.07 [1.65, 2.49]4.05 [3.67, 4.50]21% [19%, 23%]39%56%-0.01+0.442026-08-04 → 2026-08-30
tmin00Zbilinear365d27 2 QC3.17 [2.86, 3.51]0.58+2.07 [1.61, 2.52]4.05 [3.64, 4.48]21% [19%, 24%]39%56%-0.01+0.442026-08-04 → 2026-08-30
tmin00Zbilinearall27 2 QC3.17 [2.87, 3.53]0.58+2.07 [1.63, 2.55]4.05 [3.65, 4.51]21% [19%, 24%]39%56%-0.01+0.442026-08-04 → 2026-08-30
tmin00Znearest30d27 2 QC3.34 [3.07, 3.63]0.62+2.19 [1.80, 2.58]4.26 [3.88, 4.66]19% [17%, 22%]37%55%-0.06+0.392026-08-04 → 2026-08-30
tmin00Znearest90d27 2 QC3.34 [3.06, 3.68]0.62+2.19 [1.78, 2.61]4.26 [3.85, 4.72]19% [16%, 21%]37%55%-0.06+0.392026-08-04 → 2026-08-30
tmin00Znearest365d27 2 QC3.34 [3.05, 3.69]0.62+2.19 [1.74, 2.64]4.26 [3.82, 4.71]19% [16%, 22%]37%55%-0.06+0.392026-08-04 → 2026-08-30
tmin00Znearestall27 2 QC3.34 [3.06, 3.71]0.62+2.19 [1.75, 2.67]4.26 [3.82, 4.75]19% [16%, 22%]37%55%-0.06+0.392026-08-04 → 2026-08-30
tmin12Zbilinear30d27 2 QC3.08 [2.91, 3.28]0.61+1.92 [1.54, 2.33]3.88 [3.63, 4.16]20% [18%, 22%]38%56%+0.02+0.402026-08-04 → 2026-08-30
tmin12Zbilinear90d27 2 QC3.08 [2.90, 3.31]0.61+1.92 [1.52, 2.37]3.88 [3.61, 4.21]20% [18%, 22%]38%56%+0.02+0.402026-08-04 → 2026-08-30
tmin12Zbilinear365d27 2 QC3.08 [2.89, 3.31]0.61+1.92 [1.49, 2.39]3.88 [3.60, 4.19]20% [17%, 22%]38%56%+0.02+0.402026-08-04 → 2026-08-30
tmin12Zbilinearall27 2 QC3.08 [2.90, 3.31]0.61+1.92 [1.50, 2.42]3.88 [3.61, 4.19]20% [18%, 22%]38%56%+0.02+0.402026-08-04 → 2026-08-30
tmin12Znearest30d27 2 QC3.24 [3.08, 3.41]0.64+2.05 [1.66, 2.48]4.07 [3.81, 4.35]19% [16%, 22%]38%54%-0.03+0.382026-08-04 → 2026-08-30
tmin12Znearest90d27 2 QC3.24 [3.08, 3.46]0.64+2.05 [1.65, 2.52]4.07 [3.80, 4.40]19% [16%, 22%]38%54%-0.03+0.382026-08-04 → 2026-08-30
tmin12Znearest365d27 2 QC3.24 [3.07, 3.45]0.64+2.05 [1.62, 2.56]4.07 [3.78, 4.39]19% [16%, 22%]38%54%-0.03+0.382026-08-04 → 2026-08-30
tmin12Znearestall27 2 QC3.24 [3.07, 3.46]0.64+2.05 [1.61, 2.57]4.07 [3.79, 4.40]19% [16%, 23%]38%54%-0.03+0.382026-08-04 → 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 3, 00Z bilinear tmax+5+2.50-2.5-52026-08-04: -0.45 °F2026-08-05: -1.18 °F2026-08-06: +0.56 °F2026-08-07: -0.04 °F2026-08-08: +0.37 °F2026-08-09: -0.28 °F2026-08-10: +0.98 °F2026-08-11: +0.89 °F2026-08-12: -1.78 °F2026-08-13: -0.46 °F2026-08-14: -1.69 °F2026-08-15: +0.16 °F2026-08-16: -1.21 °F2026-08-17: -1.43 °F2026-08-18: -0.84 °F2026-08-19: -0.64 °F2026-08-20: +0.48 °F2026-08-21: -0.2 °F2026-08-22: -1.4 °F2026-08-23: -2.04 °F2026-08-24: -2.61 °F2026-08-25: -1.18 °F2026-08-26: -1.28 °F2026-08-27: -1.87 °F2026-08-28: -3.01 °F2026-08-29: -1.47 °F2026-08-30: -0.16 °F2026-08-042026-08-30°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 (27 days, newest first) · download CSV
Climatological dayError °F
2026-08-30-0.16
2026-08-29-1.47
2026-08-28-3.01
2026-08-27-1.87
2026-08-26-1.28
2026-08-25-1.18
2026-08-24-2.61
2026-08-23-2.04
2026-08-22-1.40
2026-08-21-0.20
2026-08-20+0.48
2026-08-19-0.64
2026-08-18-0.84
2026-08-17-1.43
2026-08-16-1.21
2026-08-15+0.16
2026-08-14-1.69
2026-08-13-0.46
2026-08-12-1.78
2026-08-11+0.89
2026-08-10+0.98
2026-08-09-0.28
2026-08-08+0.37
2026-08-07-0.04
2026-08-06+0.56
2026-08-05-1.18
2026-08-04-0.45

Error distribution

Distribution of the signed daily error in °F for NCEP GFS at ALL, lead day 3-5 to -4.5 °F: 0 days-4.5 to -4 °F: 0 days-4 to -3.5 °F: 0 days-3.5 to -3 °F: 1 day-3 to -2.5 °F: 1 day-2.5 to -2 °F: 1 day-2 to -1.5 °F: 3 days-1.5 to -1 °F: 7 days-1 to -0.5 °F: 2 days-0.5 to 0 °F: 6 days0 to 0.5 °F: 3 days0.5 to 1 °F: 3 days1 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| 0.98 · P90 |e| 1.94 °F-50+5 °Fn = 27 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
-5.00-4.500
-4.50-4.000
-4.00-3.500
-3.50-3.001
-3.00-2.501
-2.50-2.001
-2.00-1.503
-1.50-1.007
-1.00-0.502
-0.50+0.006
+0.00+0.503
+0.50+1.003
+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
2026-08271.06 -0.81

Availability

ModelScored period DaysCoverage
NCEP GFS2026-08-04 → 2026-08-30 27
NCEP GFS2026-08-04 → 2026-08-30 27
NCEP GFS2026-08-04 → 2026-08-30 27
NCEP GFS2026-08-04 → 2026-08-30 27

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 27 -0.40 [-0.60, -0.14] yes
GraphCast (IFS init) 25 -1.92 [-2.30, -1.60] yes
ECMWF IFS HRES 22 -0.35 [-0.60, 0.10] no
Persistence (baseline) 27 -0.41 [-0.82, -0.01] yes

Cite this page

ShortCastCheck, ALL gfs lead 3, methodology v0.2, accessed 2026-08-31, https://castcheck.zifanzhang.com/station/ALL/model/gfs/lead/3/

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 3. 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/3/

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