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 1

ALL · 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, 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
tmax00Zbilinear30d29 2 QC2.93 [2.78, 3.09]0.72-1.06 [-1.44, -0.59]3.79 [3.60, 3.99]25% [23%, 27%]44%60%-0.09+0.032026-08-02 → 2026-08-30
tmax00Zbilinear90d29 2 QC2.93 [2.79, 3.09]0.72-1.06 [-1.45, -0.54]3.79 [3.61, 3.99]25% [23%, 27%]44%60%-0.09+0.032026-08-02 → 2026-08-30
tmax00Zbilinear365d29 2 QC2.93 [2.79, 3.09]0.72-1.06 [-1.47, -0.58]3.79 [3.60, 3.99]25% [23%, 27%]44%60%-0.09+0.032026-08-02 → 2026-08-30
tmax00Zbilinearall29 2 QC2.93 [2.77, 3.11]0.72-1.06 [-1.48, -0.52]3.79 [3.59, 4.01]25% [23%, 27%]44%60%-0.09+0.032026-08-02 → 2026-08-30
tmax00Znearest30d29 2 QC3.17 [3.06, 3.29]0.75-0.99 [-1.41, -0.45]4.00 [3.88, 4.14]21% [20%, 23%]38%55%-0.18-0.012026-08-02 → 2026-08-30
tmax00Znearest90d29 2 QC3.17 [3.08, 3.29]0.75-0.99 [-1.44, -0.41]4.00 [3.89, 4.13]21% [20%, 23%]38%55%-0.18-0.012026-08-02 → 2026-08-30
tmax00Znearest365d29 2 QC3.17 [3.08, 3.30]0.75-0.99 [-1.47, -0.47]4.00 [3.89, 4.15]21% [20%, 23%]38%55%-0.18-0.012026-08-02 → 2026-08-30
tmax00Znearestall29 2 QC3.17 [3.07, 3.30]0.75-0.99 [-1.44, -0.38]4.00 [3.88, 4.16]21% [20%, 23%]38%55%-0.18-0.012026-08-02 → 2026-08-30
tmax12Zbilinear30d29 2 QC2.78 [2.66, 2.89]0.67-0.93 [-1.28, -0.49]3.59 [3.45, 3.73]24% [23%, 26%]48%62%-0.03+0.102026-08-02 → 2026-08-30
tmax12Zbilinear90d29 2 QC2.78 [2.66, 2.91]0.67-0.93 [-1.32, -0.47]3.59 [3.45, 3.75]24% [22%, 27%]48%62%-0.03+0.102026-08-02 → 2026-08-30
tmax12Zbilinear365d29 2 QC2.78 [2.66, 2.91]0.67-0.93 [-1.34, -0.51]3.59 [3.45, 3.76]24% [22%, 26%]48%62%-0.03+0.102026-08-02 → 2026-08-30
tmax12Zbilinearall29 2 QC2.78 [2.64, 2.92]0.67-0.93 [-1.33, -0.48]3.59 [3.43, 3.79]24% [22%, 27%]48%62%-0.03+0.102026-08-02 → 2026-08-30
tmax12Znearest30d29 2 QC3.01 [2.88, 3.12]0.68-0.88 [-1.25, -0.44]3.82 [3.67, 3.95]22% [19%, 26%]43%58%-0.12+0.082026-08-02 → 2026-08-30
tmax12Znearest90d29 2 QC3.01 [2.88, 3.12]0.68-0.88 [-1.30, -0.39]3.82 [3.67, 3.96]22% [19%, 26%]43%58%-0.12+0.082026-08-02 → 2026-08-30
tmax12Znearest365d29 2 QC3.01 [2.88, 3.13]0.68-0.88 [-1.31, -0.44]3.82 [3.68, 3.97]22% [19%, 26%]43%58%-0.12+0.082026-08-02 → 2026-08-30
tmax12Znearestall29 2 QC3.01 [2.88, 3.12]0.68-0.88 [-1.31, -0.40]3.82 [3.66, 3.97]22% [19%, 26%]43%58%-0.12+0.082026-08-02 → 2026-08-30
tmin00Zbilinear30d29 2 QC2.91 [2.72, 3.08]0.60+1.76 [1.36, 2.21]3.64 [3.42, 3.85]21% [19%, 23%]42%59%-0.24+0.202026-08-02 → 2026-08-30
tmin00Zbilinear90d29 2 QC2.91 [2.73, 3.11]0.60+1.76 [1.31, 2.22]3.64 [3.42, 3.87]21% [19%, 24%]42%59%-0.24+0.202026-08-02 → 2026-08-30
tmin00Zbilinear365d29 2 QC2.91 [2.72, 3.13]0.60+1.76 [1.30, 2.26]3.64 [3.40, 3.88]21% [19%, 24%]42%59%-0.24+0.202026-08-02 → 2026-08-30
tmin00Zbilinearall29 2 QC2.91 [2.73, 3.13]0.60+1.76 [1.30, 2.29]3.64 [3.41, 3.90]21% [19%, 24%]42%59%-0.24+0.202026-08-02 → 2026-08-30
tmin00Znearest30d29 2 QC3.04 [2.90, 3.20]0.60+1.91 [1.52, 2.34]3.84 [3.64, 4.06]21% [18%, 24%]41%57%-0.30+0.202026-08-02 → 2026-08-30
tmin00Znearest90d29 2 QC3.04 [2.89, 3.22]0.60+1.91 [1.49, 2.33]3.84 [3.62, 4.09]21% [18%, 24%]41%57%-0.30+0.202026-08-02 → 2026-08-30
tmin00Znearest365d29 2 QC3.04 [2.89, 3.22]0.60+1.91 [1.46, 2.38]3.84 [3.60, 4.08]21% [18%, 25%]41%57%-0.30+0.202026-08-02 → 2026-08-30
tmin00Znearestall29 2 QC3.04 [2.89, 3.24]0.60+1.91 [1.46, 2.40]3.84 [3.61, 4.11]21% [18%, 24%]41%57%-0.30+0.202026-08-02 → 2026-08-30
tmin12Zbilinear30d29 2 QC2.75 [2.58, 2.91]0.59+1.64 [1.30, 1.99]3.42 [3.22, 3.60]22% [20%, 25%]42%62%-0.17+0.222026-08-02 → 2026-08-30
tmin12Zbilinear90d29 2 QC2.75 [2.60, 2.94]0.59+1.64 [1.28, 2.01]3.42 [3.24, 3.63]22% [19%, 24%]42%62%-0.17+0.222026-08-02 → 2026-08-30
tmin12Zbilinear365d29 2 QC2.75 [2.58, 2.96]0.59+1.64 [1.27, 2.04]3.42 [3.21, 3.65]22% [19%, 25%]42%62%-0.17+0.222026-08-02 → 2026-08-30
tmin12Zbilinearall29 2 QC2.75 [2.59, 2.95]0.59+1.64 [1.26, 2.06]3.42 [3.23, 3.65]22% [19%, 25%]42%62%-0.17+0.222026-08-02 → 2026-08-30
tmin12Znearest30d29 2 QC2.92 [2.82, 3.02]0.63+1.78 [1.45, 2.15]3.67 [3.51, 3.83]23% [21%, 25%]41%60%-0.24+0.172026-08-02 → 2026-08-30
tmin12Znearest90d29 2 QC2.92 [2.82, 3.03]0.63+1.78 [1.42, 2.15]3.67 [3.51, 3.84]23% [21%, 25%]41%60%-0.24+0.172026-08-02 → 2026-08-30
tmin12Znearest365d29 2 QC2.92 [2.81, 3.03]0.63+1.78 [1.40, 2.19]3.67 [3.48, 3.85]23% [21%, 25%]41%60%-0.24+0.172026-08-02 → 2026-08-30
tmin12Znearestall29 2 QC2.92 [2.82, 3.04]0.63+1.78 [1.41, 2.20]3.67 [3.50, 3.87]23% [21%, 25%]41%60%-0.24+0.172026-08-02 → 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 ALL, lead day 1, 00Z bilinear tmax+2.5+1.20-1.2-2.52026-08-02: -2.15 °F2026-08-03: -1.98 °F2026-08-04: +0.16 °F2026-08-05: -1.72 °F2026-08-06: +0.35 °F2026-08-07: +0.27 °F2026-08-08: +0.33 °F2026-08-09: -0.09 °F2026-08-10: +0.48 °F2026-08-11: -0.79 °F2026-08-12: -2.1 °F2026-08-13: -0.66 °F2026-08-14: -1.13 °F2026-08-15: -0.47 °F2026-08-16: -1.48 °F2026-08-17: -1.72 °F2026-08-18: -1.07 °F2026-08-19: -0.53 °F2026-08-20: -2.21 °F2026-08-21: -1 °F2026-08-22: -2.35 °F2026-08-23: -1.28 °F2026-08-24: -1.66 °F2026-08-25: -0.82 °F2026-08-26: -1.51 °F2026-08-27: -1.07 °F2026-08-28: -1.88 °F2026-08-29: -2.05 °F2026-08-30: -0.51 °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
2026-08-30-0.51
2026-08-29-2.05
2026-08-28-1.88
2026-08-27-1.07
2026-08-26-1.51
2026-08-25-0.82
2026-08-24-1.66
2026-08-23-1.28
2026-08-22-2.35
2026-08-21-1.00
2026-08-20-2.21
2026-08-19-0.53
2026-08-18-1.07
2026-08-17-1.72
2026-08-16-1.48
2026-08-15-0.47
2026-08-14-1.13
2026-08-13-0.66
2026-08-12-2.10
2026-08-11-0.79
2026-08-10+0.48
2026-08-09-0.09
2026-08-08+0.33
2026-08-07+0.27
2026-08-06+0.35
2026-08-05-1.72
2026-08-04+0.16
2026-08-03-1.98
2026-08-02-2.15

Error distribution

Distribution of the signed daily error in °F for NCEP GFS at ALL, lead day 1-2.5 to -2.25 °F: 1 day-2.25 to -2 °F: 4 days-2 to -1.75 °F: 2 days-1.75 to -1.5 °F: 4 days-1.5 to -1.25 °F: 2 days-1.25 to -1 °F: 4 days-1 to -0.75 °F: 2 days-0.75 to -0.5 °F: 3 days-0.5 to -0.25 °F: 1 day-0.25 to 0 °F: 1 day0 to 0.25 °F: 1 day0.25 to 0.5 °F: 4 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| 1.07 · P90 |e| 2.11 °F-2.50+2.5 °Fn = 29 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
-2.50-2.251
-2.25-2.004
-2.00-1.752
-1.75-1.504
-1.50-1.252
-1.25-1.004
-1.00-0.752
-0.75-0.503
-0.50-0.251
-0.25+0.001
+0.00+0.251
+0.25+0.504
+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
2026-08291.17 -1.06

Availability

ModelScored period DaysCoverage
NCEP GFS2026-08-02 → 2026-08-30 29
NCEP GFS2026-08-02 → 2026-08-30 29
NCEP GFS2026-08-02 → 2026-08-30 29
NCEP GFS2026-08-02 → 2026-08-30 29

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 29 -0.53 [-0.66, -0.39] yes
Aurora (GFS init) 1 -3.64 [-3.64, -3.64] yes
Aurora (IFS init) 2 -2.22 [-2.42, -2.02] yes
FourCastNet v2 (GFS init) 1 -1.25 [-1.25, -1.25] yes
FourCastNet v2 (IFS init) 2 -0.94 [-1.02, -0.87] yes
GraphCast (GFS init) 1 -3.30 [-3.30, -3.30] yes
GraphCast (IFS init) 27 -2.00 [-2.17, -1.87] yes
ECMWF IFS HRES 23 -0.56 [-0.73, -0.28] yes
Pangu-Weather (GFS init) 1 -0.86 [-0.86, -0.86] yes
Pangu-Weather (IFS init) 2 -1.03 [-1.09, -0.96] yes
Persistence (baseline) 29 +0.24 [0.04, 0.47] yes

Cite this page

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

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 1. 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/1/

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