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 6

KDEN · gfs · lead 6

Target day = initialization date + 6 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
tmax00Zbilinear30d24 1 QC4.02 [2.69, 5.48]3.84-2.03 [-4.13, 0.14]5.26 [3.35, 6.90]17% [9%, 25%]38%50%+0.46+0.492026-08-07 → 2026-08-30
tmax00Zbilinear90d24 1 QC4.02 [2.49, 5.64]3.84-2.03 [-4.38, 0.62]5.26 [3.09, 7.10]17% [9%, 25%]38%50%+0.46+0.492026-08-07 → 2026-08-30
tmax00Zbilinear365d24 1 QC4.02 [2.41, 5.84]3.84-2.03 [-4.87, 0.68]5.26 [2.96, 7.30]17% [7%, 27%]38%50%+0.46+0.492026-08-07 → 2026-08-30
tmax00Zbilinearall24 1 QC4.02 [2.41, 5.73]3.84-2.03 [-4.38, 0.79]5.26 [3.00, 7.20]17% [8%, 26%]38%50%+0.46+0.492026-08-07 → 2026-08-30
tmax00Znearest30d24 1 QC3.79 [2.39, 5.32]3.70-2.14 [-4.16, -0.06]5.12 [3.09, 6.83]21% [12%, 33%]42%50%+0.49+0.512026-08-07 → 2026-08-30
tmax00Znearest90d24 1 QC3.79 [2.15, 5.47]3.70-2.14 [-4.39, 0.30]5.12 [2.69, 7.05]21% [12%, 34%]42%50%+0.49+0.512026-08-07 → 2026-08-30
tmax00Znearest365d24 1 QC3.79 [2.10, 5.67]3.70-2.14 [-4.92, 0.50]5.12 [2.56, 7.25]21% [11%, 36%]42%50%+0.49+0.512026-08-07 → 2026-08-30
tmax00Znearestall24 1 QC3.79 [2.14, 5.51]3.70-2.14 [-4.47, 0.57]5.12 [2.64, 7.12]21% [10%, 36%]42%50%+0.49+0.512026-08-07 → 2026-08-30
tmax12Zbilinear30d24 1 QC5.11 [3.68, 6.20]3.67-3.52 [-4.51, -2.30]6.08 [4.54, 7.06]4% [0%, 14%]17%38%+0.32+0.512026-08-07 → 2026-08-30
tmax12Zbilinear90d24 1 QC5.11 [3.31, 6.22]3.67-3.52 [-4.58, -2.15]6.08 [4.07, 7.06]4% [0%, 17%]17%38%+0.32+0.512026-08-07 → 2026-08-30
tmax12Zbilinear365d24 1 QC5.11 [3.29, 6.32]3.67-3.52 [-4.68, -2.16]6.08 [3.93, 7.15]4% [0%, 17%]17%38%+0.32+0.512026-08-07 → 2026-08-30
tmax12Zbilinearall24 1 QC5.11 [3.07, 6.28]3.67-3.52 [-4.66, -2.02]6.08 [3.79, 7.10]4% [0%, 17%]17%38%+0.32+0.512026-08-07 → 2026-08-30
tmax12Znearest30d24 1 QC4.94 [3.60, 5.98]3.56-3.49 [-4.49, -2.36]6.00 [4.49, 6.93]8% [0%, 15%]21%42%+0.34+0.532026-08-07 → 2026-08-30
tmax12Znearest90d24 1 QC4.94 [3.31, 6.02]3.56-3.49 [-4.64, -2.21]6.00 [4.03, 6.96]8% [0%, 14%]21%42%+0.34+0.532026-08-07 → 2026-08-30
tmax12Znearest365d24 1 QC4.94 [3.17, 6.16]3.56-3.49 [-4.69, -2.24]6.00 [3.85, 7.07]8% [0%, 14%]21%42%+0.34+0.532026-08-07 → 2026-08-30
tmax12Znearestall24 1 QC4.94 [3.01, 6.08]3.56-3.49 [-4.67, -2.14]6.00 [3.44, 7.02]8% [0%, 14%]21%42%+0.34+0.532026-08-07 → 2026-08-30
tmin00Zbilinear30d24 1 QC5.08 [3.45, 6.47]3.32+3.76 [1.69, 5.96]5.69 [4.10, 6.88]8% [0%, 26%]17%17%+0.08+0.402026-08-07 → 2026-08-30
tmin00Zbilinear90d24 1 QC5.08 [2.91, 6.51]3.32+3.76 [1.19, 6.29]5.69 [3.52, 6.90]8% [0%, 31%]17%17%+0.08+0.402026-08-07 → 2026-08-30
tmin00Zbilinear365d24 1 QC5.08 [2.86, 6.67]3.32+3.76 [1.09, 6.64]5.69 [3.46, 7.04]8% [0%, 30%]17%17%+0.08+0.402026-08-07 → 2026-08-30
tmin00Zbilinearall24 1 QC5.08 [2.92, 6.59]3.32+3.76 [1.09, 6.41]5.69 [3.55, 6.98]8% [0%, 30%]17%17%+0.08+0.402026-08-07 → 2026-08-30
tmin00Znearest30d24 1 QC5.62 [4.13, 6.97]3.12+4.45 [2.57, 6.57]6.08 [4.52, 7.29]0% [0%, 0%]8%12%-0.02+0.432026-08-07 → 2026-08-30
tmin00Znearest90d24 1 QC5.62 [3.81, 7.11]3.12+4.45 [2.20, 6.95]6.08 [4.08, 7.37]0% [0%, 0%]8%12%-0.02+0.432026-08-07 → 2026-08-30
tmin00Znearest365d24 1 QC5.62 [3.82, 7.24]3.12+4.45 [2.23, 7.16]6.08 [4.14, 7.50]0% [0%, 0%]8%12%-0.02+0.432026-08-07 → 2026-08-30
tmin00Znearestall24 1 QC5.62 [3.79, 7.14]3.12+4.45 [2.21, 7.13]6.08 [4.08, 7.46]0% [0%, 0%]8%12%-0.02+0.432026-08-07 → 2026-08-30
tmin12Zbilinear30d24 1 QC4.73 [3.62, 5.83]2.47+4.11 [2.26, 5.71]5.21 [4.18, 6.17]8% [0%, 14%]12%25%+0.14+0.552026-08-07 → 2026-08-30
tmin12Zbilinear90d24 1 QC4.73 [3.26, 6.04]2.47+4.11 [1.62, 5.95]5.21 [3.79, 6.34]8% [0%, 14%]12%25%+0.14+0.552026-08-07 → 2026-08-30
tmin12Zbilinear365d24 1 QC4.73 [3.22, 6.24]2.47+4.11 [1.68, 6.18]5.21 [3.75, 6.48]8% [0%, 14%]12%25%+0.14+0.552026-08-07 → 2026-08-30
tmin12Zbilinearall24 1 QC4.73 [3.22, 6.15]2.47+4.11 [1.57, 6.09]5.21 [3.75, 6.63]8% [0%, 14%]12%25%+0.14+0.552026-08-07 → 2026-08-30
tmin12Znearest30d24 1 QC4.87 [3.82, 6.05]2.25+4.51 [3.01, 5.98]5.38 [4.38, 6.46]8% [0%, 21%]12%17%+0.11+0.592026-08-07 → 2026-08-30
tmin12Znearest90d24 1 QC4.87 [3.44, 6.29]2.25+4.51 [2.57, 6.26]5.38 [4.05, 6.70]8% [0%, 23%]12%17%+0.11+0.592026-08-07 → 2026-08-30
tmin12Znearest365d24 1 QC4.87 [3.49, 6.43]2.25+4.51 [2.72, 6.43]5.38 [4.05, 6.75]8% [0%, 22%]12%17%+0.11+0.592026-08-07 → 2026-08-30
tmin12Znearestall24 1 QC4.87 [3.46, 6.54]2.25+4.51 [2.60, 6.47]5.38 [4.00, 6.98]8% [0%, 22%]12%17%+0.11+0.592026-08-07 → 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 6, 00Z bilinear tmax+20+100-10-202026-08-07: +4.37 °F2026-08-08: -0.15 °F2026-08-09: -1.36 °F2026-08-10: +2.21 °F2026-08-11: -1.69 °F2026-08-12: -1.89 °F2026-08-13: +3.57 °F2026-08-14: -7.11 °F2026-08-15: -1.3 °F2026-08-16: -0.76 °F2026-08-17: -4.48 °F2026-08-18: +1.46 °F2026-08-19: -7.36 °F2026-08-20: -13.37 °F2026-08-21: -11.69 °F2026-08-22: -0.6 °F2026-08-23: -2.81 °F2026-08-24: -3.63 °F2026-08-25: +2.93 °F2026-08-26: +5.1 °F2026-08-27: -0.5 °F2026-08-28: -7.94 °F2026-08-29: -6.04 °F2026-08-30: +4.24 °F2026-08-072026-08-30°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 (24 days, newest first) · download CSV
Climatological dayError °F
2026-08-30+4.24
2026-08-29-6.04
2026-08-28-7.94
2026-08-27-0.50
2026-08-26+5.10
2026-08-25+2.93
2026-08-24-3.63
2026-08-23-2.81
2026-08-22-0.60
2026-08-21-11.69
2026-08-20-13.37
2026-08-19-7.36
2026-08-18+1.46
2026-08-17-4.48
2026-08-16-0.76
2026-08-15-1.30
2026-08-14-7.11
2026-08-13+3.57
2026-08-12-1.89
2026-08-11-1.69
2026-08-10+2.21
2026-08-09-1.36
2026-08-08-0.15
2026-08-07+4.37

Error distribution

Distribution of the signed daily error in °F for NCEP GFS at KDEN, lead day 6-20 to -18 °F: 0 days-18 to -16 °F: 0 days-16 to -14 °F: 0 days-14 to -12 °F: 1 day-12 to -10 °F: 1 day-10 to -8 °F: 0 days-8 to -6 °F: 4 days-6 to -4 °F: 1 day-4 to -2 °F: 2 days-2 to 0 °F: 8 days0 to 2 °F: 1 day2 to 4 °F: 3 days4 to 6 °F: 3 days6 to 8 °F: 0 days8 to 10 °F: 0 days10 to 12 °F: 0 days12 to 14 °F: 0 days14 to 16 °F: 0 days16 to 18 °F: 0 days18 to 20 °F: 0 daysdashed: P50 |e| 3.25 · P90 |e| 7.76 °F-200+20 °Fn = 24 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
-14.00-12.001
-12.00-10.001
-10.00-8.000
-8.00-6.004
-6.00-4.001
-4.00-2.002
-2.00+0.008
+0.00+2.001
+2.00+4.003
+4.00+6.003
+6.00+8.000
+8.00+10.000
+10.00+12.000
+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
2026-08244.02 -2.03

Availability

ModelScored period DaysCoverage
NCEP GFS2026-08-07 → 2026-08-30 24
NCEP GFS2026-08-07 → 2026-08-30 24
NCEP GFS2026-08-07 → 2026-08-30 24
NCEP GFS2026-08-07 → 2026-08-30 24

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 24 -1.55 [-3.42, 1.07] no
GraphCast (IFS init) 24 -3.60 [-5.59, -1.63] yes
ECMWF IFS HRES 19 -0.40 [-3.74, 1.82] no
Persistence (baseline) 24 -3.48 [-6.85, 0.48] no

Cite this page

ShortCastCheck, KDEN gfs lead 6, methodology v0.2, accessed 2026-08-31, https://castcheck.zifanzhang.com/station/KDEN/model/gfs/lead/6/

LongCastCheck (2026). Station-level verification of raw weather-model 2 m temperature forecasts: KDEN (Denver Intl), model gfs, lead day 6. 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/6/

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