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 0

ALL · gfs · lead 0

Target day = initialization date + 0 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
tmax00Zbilinear30d30 2 QC2.65 [2.53, 2.76]0.53-1.12 [-1.37, -0.81]3.41 [3.23, 3.57]25% [22%, 27%]48%66%——2026-08-01 → 2026-08-30
tmax00Zbilinear90d30 2 QC2.65 [2.53, 2.77]0.53-1.12 [-1.41, -0.81]3.41 [3.22, 3.61]25% [22%, 27%]48%66%——2026-08-01 → 2026-08-30
tmax00Zbilinear365d30 2 QC2.65 [2.53, 2.80]0.53-1.12 [-1.44, -0.84]3.41 [3.23, 3.64]25% [22%, 27%]48%66%——2026-08-01 → 2026-08-30
tmax00Zbilinearall30 2 QC2.65 [2.53, 2.79]0.53-1.12 [-1.41, -0.80]3.41 [3.21, 3.64]25% [22%, 28%]48%66%——2026-08-01 → 2026-08-30
tmax00Znearest30d30 2 QC2.88 [2.77, 3.00]0.54-1.05 [-1.32, -0.71]3.67 [3.52, 3.81]24% [21%, 26%]45%60%——2026-08-01 → 2026-08-30
tmax00Znearest90d30 2 QC2.88 [2.76, 3.00]0.54-1.05 [-1.35, -0.68]3.67 [3.49, 3.84]24% [21%, 26%]45%60%——2026-08-01 → 2026-08-30
tmax00Znearest365d30 2 QC2.88 [2.75, 3.02]0.54-1.05 [-1.40, -0.73]3.67 [3.48, 3.87]24% [21%, 26%]45%60%——2026-08-01 → 2026-08-30
tmax00Znearestall30 2 QC2.88 [2.76, 3.01]0.54-1.05 [-1.36, -0.70]3.67 [3.50, 3.86]24% [21%, 26%]45%60%——2026-08-01 → 2026-08-30
tmin00Zbilinear30d30 2 QC2.67 [2.51, 2.82]0.53+1.59 [1.26, 1.95]3.37 [3.18, 3.55]23% [22%, 25%]46%65%——2026-08-01 → 2026-08-30
tmin00Zbilinear90d30 2 QC2.67 [2.50, 2.86]0.53+1.59 [1.23, 1.96]3.37 [3.18, 3.57]23% [22%, 25%]46%65%——2026-08-01 → 2026-08-30
tmin00Zbilinear365d30 2 QC2.67 [2.49, 2.87]0.53+1.59 [1.22, 1.99]3.37 [3.16, 3.58]23% [22%, 25%]46%65%——2026-08-01 → 2026-08-30
tmin00Zbilinearall30 2 QC2.67 [2.49, 2.88]0.53+1.59 [1.23, 2.01]3.37 [3.17, 3.60]23% [22%, 25%]46%65%——2026-08-01 → 2026-08-30
tmin00Znearest30d30 2 QC2.81 [2.71, 2.93]0.59+1.70 [1.36, 2.08]3.59 [3.42, 3.78]24% [22%, 26%]44%62%——2026-08-01 → 2026-08-30
tmin00Znearest90d30 2 QC2.81 [2.69, 2.95]0.59+1.70 [1.32, 2.08]3.59 [3.41, 3.79]24% [22%, 26%]44%62%——2026-08-01 → 2026-08-30
tmin00Znearest365d30 2 QC2.81 [2.68, 2.95]0.59+1.70 [1.31, 2.12]3.59 [3.40, 3.80]24% [22%, 26%]44%62%——2026-08-01 → 2026-08-30
tmin00Znearestall30 2 QC2.81 [2.66, 2.96]0.59+1.70 [1.31, 2.13]3.59 [3.40, 3.83]24% [22%, 26%]44%62%——2026-08-01 → 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 0, 00Z bilinear tmax+2.5+1.20-1.2-2.52026-08-01: -1.41 °F2026-08-02: -1.5 °F2026-08-03: -2.37 °F2026-08-04: -0.31 °F2026-08-05: -1.17 °F2026-08-06: -0.37 °F2026-08-07: -0.02 °F2026-08-08: +0.05 °F2026-08-09: -0.33 °F2026-08-10: -0.48 °F2026-08-11: -2.29 °F2026-08-12: -1.19 °F2026-08-13: -0.79 °F2026-08-14: -1.03 °F2026-08-15: -0.65 °F2026-08-16: -1.14 °F2026-08-17: -1.67 °F2026-08-18: -1.7 °F2026-08-19: -0.83 °F2026-08-20: -0.56 °F2026-08-21: -0.6 °F2026-08-22: -1.59 °F2026-08-23: -1.52 °F2026-08-24: -1.7 °F2026-08-25: -1.07 °F2026-08-26: -0.96 °F2026-08-27: -1.63 °F2026-08-28: -1.67 °F2026-08-29: -2.23 °F2026-08-30: -0.79 °F2026-08-012026-08-30°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 (30 days, newest first) · download CSV
Climatological dayError °F
2026-08-30-0.79
2026-08-29-2.23
2026-08-28-1.67
2026-08-27-1.63
2026-08-26-0.96
2026-08-25-1.07
2026-08-24-1.70
2026-08-23-1.52
2026-08-22-1.59
2026-08-21-0.60
2026-08-20-0.56
2026-08-19-0.83
2026-08-18-1.70
2026-08-17-1.67
2026-08-16-1.14
2026-08-15-0.65
2026-08-14-1.03
2026-08-13-0.79
2026-08-12-1.19
2026-08-11-2.29
2026-08-10-0.48
2026-08-09-0.33
2026-08-08+0.05
2026-08-07-0.02
2026-08-06-0.37
2026-08-05-1.17
2026-08-04-0.31
2026-08-03-2.37
2026-08-02-1.50
2026-08-01-1.41

Error distribution

Distribution of the signed daily error in °F for NCEP GFS at ALL, lead day 0-2.5 to -2.25 °F: 2 days-2.25 to -2 °F: 1 day-2 to -1.75 °F: 0 days-1.75 to -1.5 °F: 7 days-1.5 to -1.25 °F: 2 days-1.25 to -1 °F: 5 days-1 to -0.75 °F: 4 days-0.75 to -0.5 °F: 3 days-0.5 to -0.25 °F: 4 days-0.25 to 0 °F: 1 day0 to 0.25 °F: 1 day0.25 to 0.5 °F: 0 days0.5 to 0.75 °F: 0 days0.75 to 1 °F: 0 days1 to 1.25 °F: 0 days1.25 to 1.5 °F: 0 days1.5 to 1.75 °F: 0 days1.75 to 2 °F: 0 days2 to 2.25 °F: 0 days2.25 to 2.5 °F: 0 daysdashed: P50 |e| 1.1 · P90 |e| 1.76 °F-2.50+2.5 °Fn = 30 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
-2.50-2.252
-2.25-2.001
-2.00-1.750
-1.75-1.507
-1.50-1.252
-1.25-1.005
-1.00-0.754
-0.75-0.503
-0.50-0.254
-0.25+0.001
+0.00+0.251
+0.25+0.500
+0.50+0.750
+0.75+1.000
+1.00+1.250
+1.25+1.500
+1.50+1.750
+1.75+2.000
+2.00+2.250
+2.25+2.500

Month by month

00Z bilinear daily maximum, newest first.

Monthn MAE °FBias °F
2026-08301.12 -1.12

Availability

ModelScored period DaysCoverage
NCEP GFS2026-08-01 → 2026-08-30 30
NCEP GFS2026-08-01 → 2026-08-30 30

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 30 -0.77 [-0.90, -0.61] yes
Aurora (GFS init) 2 -2.87 [-2.96, -2.78] yes
Aurora (IFS init) 3 -2.26 [-2.69, -1.88] yes
FourCastNet v2 (GFS init) 2 -1.43 [-1.65, -1.22] yes
FourCastNet v2 (IFS init) 3 -1.77 [-2.82, -1.25] yes
GraphCast (GFS init) 2 -2.67 [-2.78, -2.57] yes
GraphCast (IFS init) 28 -1.95 [-2.13, -1.81] yes
ECMWF IFS HRES 25 -0.57 [-0.73, -0.36] yes
Pangu-Weather (GFS init) 2 -0.81 [-1.05, -0.58] yes
Pangu-Weather (IFS init) 3 -0.80 [-0.94, -0.74] yes

Cite this page

ShortCastCheck, ALL gfs lead 0, methodology v0.2, accessed 2026-08-31, https://castcheck.zifanzhang.com/station/ALL/model/gfs/lead/0/

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 0. 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/0/

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