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

Denver Intl · NCEP GFS · lead day 2

KDEN · 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, 1 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 1 QC3.39 [2.43, 4.33]2.65-1.85 [-3.52, 0.55]4.11 [3.03, 5.08]14% [0%, 30%]29%54%+0.54+0.652026-08-03 → 2026-08-30
tmax00Zbilinear90d28 1 QC3.39 [2.37, 4.40]2.65-1.85 [-3.81, 0.99]4.11 [2.88, 5.19]14% [0%, 32%]29%54%+0.54+0.652026-08-03 → 2026-08-30
tmax00Zbilinear365d28 1 QC3.39 [2.31, 4.49]2.65-1.85 [-3.89, 0.94]4.11 [2.78, 5.23]14% [0%, 30%]29%54%+0.54+0.652026-08-03 → 2026-08-30
tmax00Zbilinearall28 1 QC3.39 [2.32, 4.51]2.65-1.85 [-3.83, 0.95]4.11 [2.85, 5.38]14% [0%, 31%]29%54%+0.54+0.652026-08-03 → 2026-08-30
tmax00Znearest30d28 1 QC3.55 [2.56, 4.56]2.66-1.97 [-3.74, 0.48]4.30 [3.16, 5.35]14% [0%, 30%]25%46%+0.52+0.652026-08-03 → 2026-08-30
tmax00Znearest90d28 1 QC3.55 [2.50, 4.63]2.66-1.97 [-3.97, 0.94]4.30 [2.99, 5.46]14% [0%, 32%]25%46%+0.52+0.652026-08-03 → 2026-08-30
tmax00Znearest365d28 1 QC3.55 [2.41, 4.65]2.66-1.97 [-4.20, 0.81]4.30 [2.88, 5.47]14% [0%, 30%]25%46%+0.52+0.652026-08-03 → 2026-08-30
tmax00Znearestall28 1 QC3.55 [2.35, 4.83]2.66-1.97 [-4.07, 1.00]4.30 [2.97, 5.65]14% [0%, 31%]25%46%+0.52+0.652026-08-03 → 2026-08-30
tmax12Zbilinear30d28 1 QC3.83 [2.99, 4.79]2.92-2.42 [-4.40, 0.29]4.78 [3.90, 5.64]11% [0%, 21%]25%46%+0.48+0.612026-08-03 → 2026-08-30
tmax12Zbilinear90d28 1 QC3.83 [2.79, 4.89]2.92-2.42 [-4.52, 0.70]4.78 [3.69, 5.75]11% [0%, 23%]25%46%+0.48+0.612026-08-03 → 2026-08-30
tmax12Zbilinear365d28 1 QC3.83 [2.85, 5.00]2.92-2.42 [-4.63, 0.79]4.78 [3.65, 5.81]11% [0%, 22%]25%46%+0.48+0.612026-08-03 → 2026-08-30
tmax12Zbilinearall28 1 QC3.83 [2.83, 5.06]2.92-2.42 [-4.58, 1.02]4.78 [3.71, 5.90]11% [0%, 21%]25%46%+0.48+0.612026-08-03 → 2026-08-30
tmax12Znearest30d28 1 QC3.85 [2.99, 4.86]2.89-2.47 [-4.43, 0.15]4.81 [3.93, 5.72]14% [0%, 30%]29%50%+0.48+0.622026-08-03 → 2026-08-30
tmax12Znearest90d28 1 QC3.85 [2.90, 4.94]2.89-2.47 [-4.56, 0.68]4.81 [3.73, 5.86]14% [0%, 32%]29%50%+0.48+0.622026-08-03 → 2026-08-30
tmax12Znearest365d28 1 QC3.85 [2.94, 5.08]2.89-2.47 [-4.70, 0.69]4.81 [3.70, 5.90]14% [0%, 30%]29%50%+0.48+0.622026-08-03 → 2026-08-30
tmax12Znearestall28 1 QC3.85 [2.92, 5.13]2.89-2.47 [-4.64, 0.89]4.81 [3.73, 5.98]14% [0%, 31%]29%50%+0.48+0.622026-08-03 → 2026-08-30
tmin00Zbilinear30d28 1 QC4.79 [3.51, 6.17]2.54+4.61 [3.01, 6.17]5.67 [4.18, 7.07]7% [0%, 13%]18%39%-0.01+0.482026-08-03 → 2026-08-30
tmin00Zbilinear90d28 1 QC4.79 [3.43, 6.49]2.54+4.61 [2.94, 6.46]5.67 [4.13, 7.36]7% [0%, 14%]18%39%-0.01+0.482026-08-03 → 2026-08-30
tmin00Zbilinear365d28 1 QC4.79 [3.32, 6.51]2.54+4.61 [2.83, 6.51]5.67 [3.95, 7.29]7% [0%, 14%]18%39%-0.01+0.482026-08-03 → 2026-08-30
tmin00Zbilinearall28 1 QC4.79 [3.40, 6.70]2.54+4.61 [2.89, 6.70]5.67 [4.06, 7.46]7% [0%, 14%]18%39%-0.01+0.482026-08-03 → 2026-08-30
tmin00Znearest30d28 1 QC5.14 [3.58, 6.70]2.60+5.09 [3.45, 6.70]6.04 [4.49, 7.52]7% [0%, 20%]18%21%-0.08+0.462026-08-03 → 2026-08-30
tmin00Znearest90d28 1 QC5.14 [3.58, 7.10]2.60+5.09 [3.46, 7.10]6.04 [4.47, 7.83]7% [0%, 20%]18%21%-0.08+0.462026-08-03 → 2026-08-30
tmin00Znearest365d28 1 QC5.14 [3.43, 6.98]2.60+5.09 [3.29, 6.98]6.04 [4.30, 7.70]7% [0%, 21%]18%21%-0.08+0.462026-08-03 → 2026-08-30
tmin00Znearestall28 1 QC5.14 [3.56, 7.17]2.60+5.09 [3.44, 7.17]6.04 [4.41, 7.95]7% [0%, 20%]18%21%-0.08+0.462026-08-03 → 2026-08-30
tmin12Zbilinear30d28 1 QC4.22 [2.89, 5.76]2.53+4.18 [2.81, 5.76]5.21 [3.78, 6.61]21% [4%, 39%]29%39%+0.11+0.482026-08-03 → 2026-08-30
tmin12Zbilinear90d28 1 QC4.22 [2.88, 6.05]2.53+4.18 [2.81, 6.05]5.21 [3.79, 6.80]21% [0%, 40%]29%39%+0.11+0.482026-08-03 → 2026-08-30
tmin12Zbilinear365d28 1 QC4.22 [2.77, 5.99]2.53+4.18 [2.69, 5.95]5.21 [3.63, 6.68]21% [0%, 42%]29%39%+0.11+0.482026-08-03 → 2026-08-30
tmin12Zbilinearall28 1 QC4.22 [2.76, 6.13]2.53+4.18 [2.68, 6.12]5.21 [3.71, 6.92]21% [0%, 41%]29%39%+0.11+0.482026-08-03 → 2026-08-30
tmin12Znearest30d28 1 QC4.69 [3.19, 6.37]2.57+4.60 [3.00, 6.34]5.64 [4.14, 7.18]21% [4%, 39%]25%32%+0.01+0.472026-08-03 → 2026-08-30
tmin12Znearest90d28 1 QC4.69 [3.20, 6.60]2.57+4.60 [3.03, 6.59]5.64 [4.12, 7.47]21% [0%, 40%]25%32%+0.01+0.472026-08-03 → 2026-08-30
tmin12Znearest365d28 1 QC4.69 [3.12, 6.46]2.57+4.60 [2.89, 6.45]5.64 [4.01, 7.30]21% [0%, 42%]25%32%+0.01+0.472026-08-03 → 2026-08-30
tmin12Znearestall28 1 QC4.69 [3.14, 6.77]2.57+4.60 [2.95, 6.75]5.64 [4.07, 7.55]21% [0%, 41%]25%32%+0.01+0.472026-08-03 → 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 KDEN, lead day 2, 00Z bilinear tmax+20+100-10-202026-08-03: -4.13 °F2026-08-04: +10.92 °F2026-08-05: +3.18 °F2026-08-06: -0.06 °F2026-08-07: +3.46 °F2026-08-08: -0.32 °F2026-08-09: +0.99 °F2026-08-10: -1.45 °F2026-08-11: -1.58 °F2026-08-12: -1.81 °F2026-08-13: -2.8 °F2026-08-14: -2.86 °F2026-08-15: -2.72 °F2026-08-16: +0.29 °F2026-08-17: -6.69 °F2026-08-18: +2.8 °F2026-08-19: -5.68 °F2026-08-20: -2.4 °F2026-08-21: -6.2 °F2026-08-22: -5.44 °F2026-08-23: -3.05 °F2026-08-24: -1.42 °F2026-08-25: -2.58 °F2026-08-26: -5.73 °F2026-08-27: -5.67 °F2026-08-28: -4.88 °F2026-08-29: -3.27 °F2026-08-30: -2.59 °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
2026-08-30-2.59
2026-08-29-3.27
2026-08-28-4.88
2026-08-27-5.67
2026-08-26-5.73
2026-08-25-2.58
2026-08-24-1.42
2026-08-23-3.05
2026-08-22-5.44
2026-08-21-6.20
2026-08-20-2.40
2026-08-19-5.68
2026-08-18+2.80
2026-08-17-6.69
2026-08-16+0.29
2026-08-15-2.72
2026-08-14-2.86
2026-08-13-2.80
2026-08-12-1.81
2026-08-11-1.58
2026-08-10-1.45
2026-08-09+0.99
2026-08-08-0.32
2026-08-07+3.46
2026-08-06-0.06
2026-08-05+3.18
2026-08-04+10.92
2026-08-03-4.13

Error distribution

Distribution of the signed daily error in °F for NCEP GFS at KDEN, lead day 2-20 to -18 °F: 0 days-18 to -16 °F: 0 days-16 to -14 °F: 0 days-14 to -12 °F: 0 days-12 to -10 °F: 0 days-10 to -8 °F: 0 days-8 to -6 °F: 2 days-6 to -4 °F: 6 days-4 to -2 °F: 8 days-2 to 0 °F: 6 days0 to 2 °F: 2 days2 to 4 °F: 3 days4 to 6 °F: 0 days6 to 8 °F: 0 days8 to 10 °F: 0 days10 to 12 °F: 1 day12 to 14 °F: 0 days14 to 16 °F: 0 days16 to 18 °F: 0 days18 to 20 °F: 0 daysdashed: P50 |e| 2.83 · P90 |e| 5.87 °F-200+20 °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
-20.00-18.000
-18.00-16.000
-16.00-14.000
-14.00-12.000
-12.00-10.000
-10.00-8.000
-8.00-6.002
-6.00-4.006
-4.00-2.008
-2.00+0.006
+0.00+2.002
+2.00+4.003
+4.00+6.000
+6.00+8.000
+8.00+10.000
+10.00+12.001
+12.00+14.000
+14.00+16.000
+16.00+18.000
+18.00+20.000

Month by month

00Z bilinear daily maximum, newest first.

Monthn MAE °FBias °F
2026-08283.39 -1.85

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 -0.61 [-1.85, 0.71] no
Aurora (IFS init) 1 -0.76 [-0.76, -0.76] yes
FourCastNet v2 (IFS init) 1 -1.49 [-1.49, -1.49] yes
GraphCast (IFS init) 26 -2.98 [-4.39, -1.23] yes
ECMWF IFS HRES 23 -0.17 [-0.94, 0.67] no
Pangu-Weather (IFS init) 1 +1.89 [1.89, 1.89] yes
Persistence (baseline) 28 -4.04 [-8.92, -1.32] yes

Cite this page

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

LongCastCheck (2026). Station-level verification of raw weather-model 2 m temperature forecasts: KDEN (Denver Intl), 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/KDEN/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