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

Washington Reagan · NCEP GFS · lead day 5

KDCA · gfs · lead 5

Target day = initialization date + 5 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
tmax00Zbilinear30d25 1 QC4.34 [3.42, 5.26]3.82-2.18 [-3.66, -0.21]5.62 [4.52, 6.61]20% [8%, 32%]28%36%+0.10+0.212026-08-06 → 2026-08-30
tmax00Zbilinear90d25 1 QC4.34 [3.37, 5.41]3.82-2.18 [-3.73, 0.09]5.62 [4.46, 6.76]20% [7%, 33%]28%36%+0.10+0.212026-08-06 → 2026-08-30
tmax00Zbilinear365d25 1 QC4.34 [3.24, 5.46]3.82-2.18 [-3.88, -0.01]5.62 [4.42, 6.76]20% [5%, 33%]28%36%+0.10+0.212026-08-06 → 2026-08-30
tmax00Zbilinearall25 1 QC4.34 [3.32, 5.48]3.82-2.18 [-3.79, 0.37]5.62 [4.35, 6.81]20% [0%, 33%]28%36%+0.10+0.212026-08-06 → 2026-08-30
tmax00Znearest30d25 1 QC4.34 [3.43, 5.23]4.02-2.05 [-3.50, -0.08]5.73 [4.57, 6.71]20% [0%, 38%]24%36%+0.10+0.172026-08-06 → 2026-08-30
tmax00Znearest90d25 1 QC4.34 [3.39, 5.40]4.02-2.05 [-3.55, 0.19]5.73 [4.58, 6.82]20% [0%, 41%]24%36%+0.10+0.172026-08-06 → 2026-08-30
tmax00Znearest365d25 1 QC4.34 [3.27, 5.42]4.02-2.05 [-3.65, 0.15]5.73 [4.49, 6.83]20% [0%, 43%]24%36%+0.10+0.172026-08-06 → 2026-08-30
tmax00Znearestall25 1 QC4.34 [3.31, 5.49]4.02-2.05 [-3.57, 0.46]5.73 [4.39, 6.89]20% [0%, 42%]24%36%+0.10+0.172026-08-06 → 2026-08-30
tmax12Zbilinear30d25 1 QC3.98 [2.64, 5.06]4.37-2.04 [-4.12, 0.80]6.09 [3.92, 7.62]36% [22%, 46%]52%56%+0.18+0.102026-08-06 → 2026-08-30
tmax12Zbilinear90d25 1 QC3.98 [2.52, 5.15]4.37-2.04 [-4.43, 2.15]6.09 [3.25, 7.81]36% [21%, 47%]52%56%+0.18+0.102026-08-06 → 2026-08-30
tmax12Zbilinear365d25 1 QC3.98 [2.50, 5.26]4.37-2.04 [-4.62, 1.78]6.09 [3.08, 7.89]36% [20%, 47%]52%56%+0.18+0.102026-08-06 → 2026-08-30
tmax12Zbilinearall25 1 QC3.98 [2.38, 5.16]4.37-2.04 [-4.68, 1.84]6.09 [3.03, 7.85]36% [18%, 48%]52%56%+0.18+0.102026-08-06 → 2026-08-30
tmax12Znearest30d25 1 QC3.96 [2.80, 5.01]4.26-1.75 [-3.96, 1.15]5.96 [3.88, 7.50]32% [19%, 44%]48%56%+0.18+0.122026-08-06 → 2026-08-30
tmax12Znearest90d25 1 QC3.96 [2.74, 5.11]4.26-1.75 [-4.30, 2.50]5.96 [3.37, 7.67]32% [17%, 45%]48%56%+0.18+0.122026-08-06 → 2026-08-30
tmax12Znearest365d25 1 QC3.96 [2.66, 5.23]4.26-1.75 [-4.46, 2.23]5.96 [3.34, 7.76]32% [17%, 46%]48%56%+0.18+0.122026-08-06 → 2026-08-30
tmax12Znearestall25 1 QC3.96 [2.63, 5.12]4.26-1.75 [-4.59, 2.20]5.96 [3.20, 7.72]32% [18%, 45%]48%56%+0.18+0.122026-08-06 → 2026-08-30
tmin00Zbilinear30d25 1 QC2.98 [1.93, 4.21]3.10-1.00 [-2.96, 0.63]3.94 [2.34, 5.39]28% [10%, 45%]44%64%+0.25+0.222026-08-06 → 2026-08-30
tmin00Zbilinear90d25 1 QC2.98 [1.77, 4.42]3.10-1.00 [-3.05, 0.70]3.94 [2.11, 5.57]28% [8%, 50%]44%64%+0.25+0.222026-08-06 → 2026-08-30
tmin00Zbilinear365d25 1 QC2.98 [1.72, 4.39]3.10-1.00 [-3.10, 0.80]3.94 [1.99, 5.59]28% [0%, 50%]44%64%+0.25+0.222026-08-06 → 2026-08-30
tmin00Zbilinearall25 1 QC2.98 [1.68, 4.37]3.10-1.00 [-3.14, 1.00]3.94 [1.95, 5.65]28% [5%, 50%]44%64%+0.25+0.222026-08-06 → 2026-08-30
tmin00Znearest30d25 1 QC3.02 [1.94, 4.27]3.12-1.45 [-3.41, 0.27]4.02 [2.36, 5.44]24% [13%, 35%]44%68%+0.24+0.222026-08-06 → 2026-08-30
tmin00Znearest90d25 1 QC3.02 [1.76, 4.41]3.12-1.45 [-3.44, 0.27]4.02 [2.08, 5.59]24% [13%, 36%]44%68%+0.24+0.222026-08-06 → 2026-08-30
tmin00Znearest365d25 1 QC3.02 [1.74, 4.46]3.12-1.45 [-3.55, 0.37]4.02 [1.97, 5.65]24% [12%, 36%]44%68%+0.24+0.222026-08-06 → 2026-08-30
tmin00Znearestall25 1 QC3.02 [1.72, 4.44]3.12-1.45 [-3.60, 0.68]4.02 [1.95, 5.65]24% [12%, 36%]44%68%+0.24+0.222026-08-06 → 2026-08-30
tmin12Zbilinear30d25 1 QC3.02 [2.16, 4.00]2.94-1.12 [-2.85, 0.42]3.70 [2.63, 4.80]28% [12%, 44%]32%44%+0.24+0.262026-08-06 → 2026-08-30
tmin12Zbilinear90d25 1 QC3.02 [2.09, 4.00]2.94-1.12 [-2.86, 0.53]3.70 [2.59, 4.84]28% [10%, 46%]32%44%+0.24+0.262026-08-06 → 2026-08-30
tmin12Zbilinear365d25 1 QC3.02 [1.97, 4.11]2.94-1.12 [-3.00, 0.53]3.70 [2.48, 4.89]28% [9%, 50%]32%44%+0.24+0.262026-08-06 → 2026-08-30
tmin12Zbilinearall25 1 QC3.02 [2.01, 4.09]2.94-1.12 [-3.02, 0.81]3.70 [2.47, 4.85]28% [10%, 46%]32%44%+0.24+0.262026-08-06 → 2026-08-30
tmin12Znearest30d25 1 QC3.15 [2.30, 4.08]2.75-1.64 [-3.34, -0.17]3.83 [2.65, 4.93]12% [4%, 20%]40%52%+0.20+0.312026-08-06 → 2026-08-30
tmin12Znearest90d25 1 QC3.15 [2.24, 4.14]2.75-1.64 [-3.32, -0.10]3.83 [2.55, 4.98]12% [0%, 21%]40%52%+0.20+0.312026-08-06 → 2026-08-30
tmin12Znearest365d25 1 QC3.15 [2.16, 4.16]2.75-1.64 [-3.44, -0.07]3.83 [2.47, 5.03]12% [0%, 21%]40%52%+0.20+0.312026-08-06 → 2026-08-30
tmin12Znearestall25 1 QC3.15 [2.18, 4.17]2.75-1.64 [-3.49, 0.21]3.83 [2.48, 5.00]12% [0%, 21%]40%52%+0.20+0.312026-08-06 → 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 KDCA, lead day 5, 00Z bilinear tmax+20+100-10-202026-08-06: +1.87 °F2026-08-07: +6.67 °F2026-08-08: -0.22 °F2026-08-09: -0.67 °F2026-08-10: -10.44 °F2026-08-11: -2.28 °F2026-08-12: -1.07 °F2026-08-13: -0.54 °F2026-08-14: -5.53 °F2026-08-15: -3.28 °F2026-08-16: +8.49 °F2026-08-17: -4.23 °F2026-08-18: -0.69 °F2026-08-19: -2.79 °F2026-08-20: -5.03 °F2026-08-21: -11.68 °F2026-08-22: -5.24 °F2026-08-23: -3.75 °F2026-08-24: +0.41 °F2026-08-25: -3.15 °F2026-08-26: +3.22 °F2026-08-27: -14.2 °F2026-08-28: -3.34 °F2026-08-29: +6.27 °F2026-08-30: -3.37 °F2026-08-062026-08-30°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 (25 days, newest first) · download CSV
Climatological dayError °F
2026-08-30-3.37
2026-08-29+6.27
2026-08-28-3.34
2026-08-27-14.20
2026-08-26+3.22
2026-08-25-3.15
2026-08-24+0.41
2026-08-23-3.75
2026-08-22-5.24
2026-08-21-11.68
2026-08-20-5.03
2026-08-19-2.79
2026-08-18-0.69
2026-08-17-4.23
2026-08-16+8.49
2026-08-15-3.28
2026-08-14-5.53
2026-08-13-0.54
2026-08-12-1.07
2026-08-11-2.28
2026-08-10-10.44
2026-08-09-0.67
2026-08-08-0.22
2026-08-07+6.67
2026-08-06+1.87

Error distribution

Distribution of the signed daily error in °F for NCEP GFS at KDCA, lead day 5-20 to -18 °F: 0 days-18 to -16 °F: 0 days-16 to -14 °F: 1 day-14 to -12 °F: 0 days-12 to -10 °F: 2 days-10 to -8 °F: 0 days-8 to -6 °F: 0 days-6 to -4 °F: 4 days-4 to -2 °F: 7 days-2 to 0 °F: 5 days0 to 2 °F: 2 days2 to 4 °F: 1 day4 to 6 °F: 0 days6 to 8 °F: 2 days8 to 10 °F: 1 day10 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| 3.34 · P90 |e| 9.66 °F-200+20 °Fn = 25 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
-16.00-14.001
-14.00-12.000
-12.00-10.002
-10.00-8.000
-8.00-6.000
-6.00-4.004
-4.00-2.007
-2.00+0.005
+0.00+2.002
+2.00+4.001
+4.00+6.000
+6.00+8.002
+8.00+10.001
+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
2026-08254.34 -2.18

Availability

ModelScored period DaysCoverage
NCEP GFS2026-08-06 → 2026-08-30 25
NCEP GFS2026-08-06 → 2026-08-30 25
NCEP GFS2026-08-06 → 2026-08-30 25
NCEP GFS2026-08-06 → 2026-08-30 25

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 25 +0.79 [0.06, 1.71] yes
GraphCast (IFS init) 25 -0.44 [-1.20, 0.54] no
ECMWF IFS HRES 18 +1.05 [-0.15, 2.43] no
Persistence (baseline) 25 -0.50 [-1.53, 0.87] no

Cite this page

ShortCastCheck, KDCA gfs lead 5, methodology v0.2, accessed 2026-08-31, https://castcheck.zifanzhang.com/station/KDCA/model/gfs/lead/5/

LongCastCheck (2026). Station-level verification of raw weather-model 2 m temperature forecasts: KDCA (Washington Reagan), model gfs, lead day 5. Methodology version 0.2, schema version 0.1, data through 2026-08-30. Accessed 2026-08-31. https://castcheck.zifanzhang.com/station/KDCA/model/gfs/lead/5/

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