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 2

ALL · gfs · lead 2

Target day = initialization date + 2 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
tmax00Zbilinear30d28 2 QC3.07 [2.85, 3.34]0.90-1.04 [-1.54, -0.51]3.96 [3.69, 4.27]21% [18%, 24%]41%59%+0.07+0.172026-08-03 → 2026-08-30
tmax00Zbilinear90d28 2 QC3.07 [2.82, 3.37]0.90-1.04 [-1.58, -0.44]3.96 [3.65, 4.33]21% [17%, 24%]41%59%+0.07+0.172026-08-03 → 2026-08-30
tmax00Zbilinear365d28 2 QC3.07 [2.81, 3.40]0.90-1.04 [-1.62, -0.47]3.96 [3.64, 4.35]21% [17%, 24%]41%59%+0.07+0.172026-08-03 → 2026-08-30
tmax00Zbilinearall28 2 QC3.07 [2.81, 3.42]0.90-1.04 [-1.63, -0.45]3.96 [3.64, 4.44]21% [17%, 24%]41%59%+0.07+0.172026-08-03 → 2026-08-30
tmax00Znearest30d28 2 QC3.33 [3.08, 3.58]0.93-1.03 [-1.57, -0.45]4.24 [3.93, 4.53]19% [16%, 22%]38%52%-0.01+0.142026-08-03 → 2026-08-30
tmax00Znearest90d28 2 QC3.33 [3.08, 3.61]0.93-1.03 [-1.61, -0.38]4.24 [3.92, 4.58]19% [16%, 22%]38%52%-0.01+0.142026-08-03 → 2026-08-30
tmax00Znearest365d28 2 QC3.33 [3.04, 3.61]0.93-1.03 [-1.65, -0.43]4.24 [3.89, 4.58]19% [16%, 22%]38%52%-0.01+0.142026-08-03 → 2026-08-30
tmax00Znearestall28 2 QC3.33 [3.06, 3.63]0.93-1.03 [-1.66, -0.37]4.24 [3.91, 4.64]19% [16%, 22%]38%52%-0.01+0.142026-08-03 → 2026-08-30
tmax12Zbilinear30d28 2 QC2.98 [2.81, 3.17]0.87-0.96 [-1.57, -0.37]3.88 [3.64, 4.14]22% [19%, 24%]45%60%+0.10+0.202026-08-03 → 2026-08-30
tmax12Zbilinear90d28 2 QC2.98 [2.80, 3.20]0.87-0.96 [-1.61, -0.31]3.88 [3.61, 4.18]22% [19%, 25%]45%60%+0.10+0.202026-08-03 → 2026-08-30
tmax12Zbilinear365d28 2 QC2.98 [2.78, 3.21]0.87-0.96 [-1.67, -0.29]3.88 [3.58, 4.18]22% [19%, 25%]45%60%+0.10+0.202026-08-03 → 2026-08-30
tmax12Zbilinearall28 2 QC2.98 [2.79, 3.22]0.87-0.96 [-1.65, -0.30]3.88 [3.58, 4.23]22% [19%, 25%]45%60%+0.10+0.202026-08-03 → 2026-08-30
tmax12Znearest30d28 2 QC3.23 [3.04, 3.42]0.92-0.92 [-1.59, -0.30]4.16 [3.87, 4.42]20% [17%, 22%]41%55%+0.02+0.152026-08-03 → 2026-08-30
tmax12Znearest90d28 2 QC3.23 [3.02, 3.45]0.92-0.92 [-1.65, -0.23]4.16 [3.86, 4.48]20% [17%, 23%]41%55%+0.02+0.152026-08-03 → 2026-08-30
tmax12Znearest365d28 2 QC3.23 [3.00, 3.47]0.92-0.92 [-1.71, -0.22]4.16 [3.83, 4.49]20% [17%, 24%]41%55%+0.02+0.152026-08-03 → 2026-08-30
tmax12Znearestall28 2 QC3.23 [3.01, 3.46]0.92-0.92 [-1.67, -0.22]4.16 [3.84, 4.49]20% [17%, 23%]41%55%+0.02+0.152026-08-03 → 2026-08-30
tmin00Zbilinear30d28 2 QC2.95 [2.75, 3.18]0.62+1.74 [1.35, 2.15]3.71 [3.45, 3.98]23% [21%, 25%]41%59%+0.00+0.332026-08-03 → 2026-08-30
tmin00Zbilinear90d28 2 QC2.95 [2.75, 3.22]0.62+1.74 [1.33, 2.15]3.71 [3.44, 4.04]23% [20%, 25%]41%59%+0.00+0.332026-08-03 → 2026-08-30
tmin00Zbilinear365d28 2 QC2.95 [2.72, 3.25]0.62+1.74 [1.30, 2.21]3.71 [3.41, 4.05]23% [20%, 25%]41%59%+0.00+0.332026-08-03 → 2026-08-30
tmin00Zbilinearall28 2 QC2.95 [2.73, 3.24]0.62+1.74 [1.32, 2.23]3.71 [3.43, 4.05]23% [20%, 25%]41%59%+0.00+0.332026-08-03 → 2026-08-30
tmin00Znearest30d28 2 QC3.09 [2.90, 3.28]0.61+1.85 [1.49, 2.23]3.91 [3.64, 4.17]21% [19%, 24%]41%57%-0.04+0.352026-08-03 → 2026-08-30
tmin00Znearest90d28 2 QC3.09 [2.89, 3.33]0.61+1.85 [1.47, 2.25]3.91 [3.62, 4.23]21% [18%, 24%]41%57%-0.04+0.352026-08-03 → 2026-08-30
tmin00Znearest365d28 2 QC3.09 [2.88, 3.35]0.61+1.85 [1.43, 2.31]3.91 [3.60, 4.27]21% [18%, 24%]41%57%-0.04+0.352026-08-03 → 2026-08-30
tmin00Znearestall28 2 QC3.09 [2.89, 3.35]0.61+1.85 [1.46, 2.33]3.91 [3.62, 4.24]21% [18%, 24%]41%57%-0.04+0.352026-08-03 → 2026-08-30
tmin12Zbilinear30d28 2 QC2.91 [2.71, 3.15]0.61+1.77 [1.42, 2.16]3.65 [3.37, 3.95]22% [19%, 24%]40%60%+0.02+0.352026-08-03 → 2026-08-30
tmin12Zbilinear90d28 2 QC2.91 [2.72, 3.19]0.61+1.77 [1.40, 2.18]3.65 [3.39, 4.00]22% [19%, 25%]40%60%+0.02+0.352026-08-03 → 2026-08-30
tmin12Zbilinear365d28 2 QC2.91 [2.69, 3.20]0.61+1.77 [1.37, 2.22]3.65 [3.34, 3.99]22% [19%, 25%]40%60%+0.02+0.352026-08-03 → 2026-08-30
tmin12Zbilinearall28 2 QC2.91 [2.70, 3.21]0.61+1.77 [1.38, 2.24]3.65 [3.35, 4.05]22% [19%, 24%]40%60%+0.02+0.352026-08-03 → 2026-08-30
tmin12Znearest30d28 2 QC3.04 [2.88, 3.21]0.65+1.93 [1.57, 2.34]3.86 [3.60, 4.11]21% [19%, 24%]42%57%-0.03+0.312026-08-03 → 2026-08-30
tmin12Znearest90d28 2 QC3.04 [2.87, 3.25]0.65+1.93 [1.55, 2.37]3.86 [3.60, 4.15]21% [19%, 24%]42%57%-0.03+0.312026-08-03 → 2026-08-30
tmin12Znearest365d28 2 QC3.04 [2.85, 3.25]0.65+1.93 [1.50, 2.40]3.86 [3.57, 4.16]21% [19%, 24%]42%57%-0.03+0.312026-08-03 → 2026-08-30
tmin12Znearestall28 2 QC3.04 [2.86, 3.27]0.65+1.93 [1.53, 2.41]3.86 [3.58, 4.19]21% [19%, 24%]42%57%-0.03+0.312026-08-03 → 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 2, 00Z bilinear tmax+5+2.50-2.5-52026-08-03: -3.32 °F2026-08-04: +0.18 °F2026-08-05: -0.8 °F2026-08-06: -0.24 °F2026-08-07: +0.6 °F2026-08-08: -0.14 °F2026-08-09: -0.68 °F2026-08-10: +1.12 °F2026-08-11: -0.02 °F2026-08-12: -1.59 °F2026-08-13: -1.94 °F2026-08-14: -0.6 °F2026-08-15: -0.33 °F2026-08-16: -1.38 °F2026-08-17: -1 °F2026-08-18: -1.16 °F2026-08-19: -0.28 °F2026-08-20: -2.82 °F2026-08-21: -0.29 °F2026-08-22: -2.93 °F2026-08-23: -2.05 °F2026-08-24: -2.41 °F2026-08-25: -0.67 °F2026-08-26: -1.72 °F2026-08-27: -2.16 °F2026-08-28: -1.56 °F2026-08-29: -0.94 °F2026-08-30: +0.05 °F2026-08-032026-08-30°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 (28 days, newest first) · download CSV
Climatological dayError °F
2026-08-30+0.05
2026-08-29-0.94
2026-08-28-1.56
2026-08-27-2.16
2026-08-26-1.72
2026-08-25-0.67
2026-08-24-2.41
2026-08-23-2.05
2026-08-22-2.93
2026-08-21-0.29
2026-08-20-2.82
2026-08-19-0.28
2026-08-18-1.16
2026-08-17-1.00
2026-08-16-1.38
2026-08-15-0.33
2026-08-14-0.60
2026-08-13-1.94
2026-08-12-1.59
2026-08-11-0.02
2026-08-10+1.12
2026-08-09-0.68
2026-08-08-0.14
2026-08-07+0.60
2026-08-06-0.24
2026-08-05-0.80
2026-08-04+0.18
2026-08-03-3.32

Error distribution

Distribution of the signed daily error in °F for NCEP GFS at ALL, lead day 2-5 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: 2 days-2.5 to -2 °F: 3 days-2 to -1.5 °F: 4 days-1.5 to -1 °F: 2 days-1 to -0.5 °F: 6 days-0.5 to 0 °F: 6 days0 to 0.5 °F: 2 days0.5 to 1 °F: 1 day1 to 1.5 °F: 1 day1.5 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| 0.97 · P90 |e| 2.53 °F-50+5 °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
-5.00-4.500
-4.50-4.000
-4.00-3.500
-3.50-3.001
-3.00-2.502
-2.50-2.003
-2.00-1.504
-1.50-1.002
-1.00-0.506
-0.50+0.006
+0.00+0.502
+0.50+1.001
+1.00+1.501
+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
2026-08281.18 -1.04

Availability

ModelScored period DaysCoverage
NCEP GFS2026-08-03 → 2026-08-30 28
NCEP GFS2026-08-03 → 2026-08-30 28
NCEP GFS2026-08-03 → 2026-08-30 28
NCEP GFS2026-08-03 → 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 -0.55 [-0.69, -0.37] yes
Aurora (IFS init) 1 -1.89 [-1.89, -1.89] yes
FourCastNet v2 (IFS init) 1 -0.53 [-0.53, -0.53] yes
GraphCast (IFS init) 26 -2.02 [-2.20, -1.74] yes
ECMWF IFS HRES 23 -0.27 [-0.55, 0.17] no
Pangu-Weather (IFS init) 1 -0.91 [-0.91, -0.91] yes
Persistence (baseline) 28 -0.22 [-0.58, 0.04] no

Cite this page

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

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 2. 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/2/

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