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 · GraphCast (IFS init) · lead day 5

KDCA · graphcast_ifs · 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, GRAP_v100, starting 2026-01-01 — 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 QC4.78 [3.61, 5.78]2.69-4.29 [-5.40, -3.34]5.51 [4.44, 6.37]8% [0%, 19%]20%32%+0.01+0.452026-08-06 → 2026-08-30
tmax00Zbilinear90d25 1 QC4.78 [3.38, 5.97]2.69-4.29 [-5.66, -3.28]5.51 [4.07, 6.47]8% [0%, 20%]20%32%+0.01+0.452026-08-06 → 2026-08-30
tmax00Zbilinear365d31 1 QC4.96 [3.68, 5.98]3.56-3.06 [-5.07, -0.26]5.74 [4.59, 6.67]10% [0%, 21%]19%29%+0.22+0.412026-01-06 → 2026-08-30
tmax00Zbilinearall31 1 QC4.96 [3.73, 6.04]3.56-3.06 [-5.04, 0.06]5.74 [4.55, 6.72]10% [0%, 21%]19%29%+0.22+0.412026-01-06 → 2026-08-30
tmax00Znearest30d25 1 QC4.67 [3.50, 5.69]2.70-4.17 [-5.29, -3.21]5.43 [4.35, 6.28]8% [0%, 19%]28%32%+0.03+0.442026-08-06 → 2026-08-30
tmax00Znearest90d25 1 QC4.67 [3.25, 5.88]2.70-4.17 [-5.57, -3.15]5.43 [3.97, 6.39]8% [0%, 20%]28%32%+0.03+0.442026-08-06 → 2026-08-30
tmax00Znearest365d31 1 QC4.86 [3.58, 5.96]3.55-2.92 [-5.01, -0.08]5.69 [4.48, 6.68]10% [0%, 21%]26%29%+0.23+0.412026-01-06 → 2026-08-30
tmax00Znearestall31 1 QC4.86 [3.61, 6.03]3.55-2.92 [-4.94, 0.28]5.69 [4.45, 6.72]10% [0%, 21%]26%29%+0.23+0.412026-01-06 → 2026-08-30
tmax12Zbilinear30d25 1 QC5.07 [3.91, 6.40]2.89-4.74 [-6.25, -3.55]5.86 [4.73, 7.02]4% [0%, 11%]24%32%-0.05+0.402026-08-06 → 2026-08-30
tmax12Zbilinear90d25 1 QC5.07 [3.77, 6.62]2.89-4.74 [-6.52, -3.50]5.86 [4.56, 7.17]4% [0%, 12%]24%32%-0.05+0.402026-08-06 → 2026-08-30
tmax12Zbilinear365d30 1 QC5.09 [3.94, 6.40]3.42-3.71 [-5.90, -1.05]5.88 [4.75, 7.02]3% [0%, 10%]23%33%+0.22+0.442026-01-06 → 2026-08-30
tmax12Zbilinearall30 1 QC5.09 [3.93, 6.45]3.42-3.71 [-5.81, -0.84]5.88 [4.78, 6.97]3% [0%, 10%]23%33%+0.22+0.442026-01-06 → 2026-08-30
tmax12Znearest30d25 1 QC4.95 [3.79, 6.32]2.87-4.61 [-6.16, -3.40]5.76 [4.63, 6.94]8% [0%, 14%]24%32%-0.02+0.412026-08-06 → 2026-08-30
tmax12Znearest90d25 1 QC4.95 [3.64, 6.53]2.87-4.61 [-6.45, -3.34]5.76 [4.42, 7.10]8% [0%, 14%]24%32%-0.02+0.412026-08-06 → 2026-08-30
tmax12Znearest365d30 1 QC4.99 [3.81, 6.34]3.40-3.58 [-5.80, -0.90]5.81 [4.62, 6.95]7% [0%, 13%]23%33%+0.23+0.452026-01-06 → 2026-08-30
tmax12Znearestall30 1 QC4.99 [3.80, 6.40]3.40-3.58 [-5.72, -0.71]5.81 [4.68, 6.93]7% [0%, 14%]23%33%+0.23+0.452026-01-06 → 2026-08-30
tmin00Zbilinear30d25 1 QC2.88 [2.38, 3.33]2.87+0.24 [-1.46, 1.96]3.39 [2.77, 3.80]20% [4%, 36%]44%52%+0.27+0.282026-08-06 → 2026-08-30
tmin00Zbilinear90d25 1 QC2.88 [2.30, 3.35]2.87+0.24 [-1.68, 2.18]3.39 [2.66, 3.83]20% [0%, 37%]44%52%+0.27+0.282026-08-06 → 2026-08-30
tmin00Zbilinear365d31 1 QC3.24 [2.46, 4.16]3.14+1.10 [-1.11, 3.49]4.04 [2.99, 5.27]19% [5%, 35%]39%48%+0.30+0.312026-01-06 → 2026-08-30
tmin00Zbilinearall31 1 QC3.24 [2.52, 4.20]3.14+1.10 [-1.11, 3.46]4.04 [3.02, 5.33]19% [5%, 33%]39%48%+0.30+0.312026-01-06 → 2026-08-30
tmin00Znearest30d25 1 QC2.89 [2.26, 3.43]2.84+0.83 [-0.87, 2.50]3.45 [2.71, 4.00]16% [0%, 33%]36%56%+0.27+0.292026-08-06 → 2026-08-30
tmin00Znearest90d25 1 QC2.89 [2.12, 3.44]2.84+0.83 [-1.06, 2.74]3.45 [2.55, 4.02]16% [0%, 33%]36%56%+0.27+0.292026-08-06 → 2026-08-30
tmin00Znearest365d31 1 QC3.32 [2.34, 4.44]3.11+1.66 [-0.49, 4.03]4.17 [2.86, 5.53]16% [0%, 33%]32%52%+0.29+0.322026-01-06 → 2026-08-30
tmin00Znearestall31 1 QC3.32 [2.40, 4.45]3.11+1.66 [-0.51, 3.97]4.17 [2.91, 5.56]16% [0%, 30%]32%52%+0.29+0.322026-01-06 → 2026-08-30
tmin12Zbilinear30d25 1 QC3.10 [2.31, 3.73]3.10+0.06 [-1.78, 1.84]3.68 [2.60, 4.40]12% [3%, 22%]28%52%+0.22+0.222026-08-06 → 2026-08-30
tmin12Zbilinear90d25 1 QC3.10 [2.20, 3.83]3.10+0.06 [-1.95, 1.96]3.68 [2.43, 4.48]12% [0%, 24%]28%52%+0.22+0.222026-08-06 → 2026-08-30
tmin12Zbilinear365d30 1 QC3.35 [2.40, 4.29]3.26+0.77 [-1.52, 3.17]4.04 [2.78, 5.10]13% [3%, 25%]27%50%+0.29+0.302026-01-06 → 2026-08-30
tmin12Zbilinearall30 1 QC3.35 [2.45, 4.29]3.26+0.77 [-1.56, 3.17]4.04 [2.79, 5.10]13% [0%, 25%]27%50%+0.29+0.302026-01-06 → 2026-08-30
tmin12Znearest30d25 1 QC3.07 [2.31, 3.77]3.05+0.63 [-1.20, 2.41]3.69 [2.56, 4.55]8% [0%, 17%]36%52%+0.22+0.232026-08-06 → 2026-08-30
tmin12Znearest90d25 1 QC3.07 [2.12, 3.84]3.05+0.63 [-1.36, 2.52]3.69 [2.32, 4.60]8% [0%, 17%]36%52%+0.22+0.232026-08-06 → 2026-08-30
tmin12Znearest365d30 1 QC3.35 [2.36, 4.36]3.19+1.30 [-0.94, 3.62]4.11 [2.73, 5.34]10% [0%, 20%]33%50%+0.29+0.322026-01-06 → 2026-08-30
tmin12Znearestall30 1 QC3.35 [2.38, 4.35]3.19+1.30 [-0.97, 3.60]4.11 [2.70, 5.34]10% [0%, 20%]33%50%+0.29+0.322026-01-06 → 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 GraphCast (IFS init) at KDCA, lead day 5, 00Z bilinear tmax+20+100-10-202026-08-06: -1.24 °F2026-08-07: -3.48 °F2026-08-08: -5.72 °F2026-08-09: -6.36 °F2026-08-10: -2.74 °F2026-08-11: -0.9 °F2026-08-12: -2.14 °F2026-08-13: -2.02 °F2026-08-14: -0.87 °F2026-08-15: -11.09 °F2026-08-16: -1.34 °F2026-08-17: -7.8 °F2026-08-18: -5.18 °F2026-08-19: -6.57 °F2026-08-20: -4.84 °F2026-08-21: -4.28 °F2026-08-22: +6.2 °F2026-08-23: -3.27 °F2026-08-24: -5.94 °F2026-08-25: -7.66 °F2026-08-26: -5.25 °F2026-08-27: -9.71 °F2026-08-28: -7.45 °F2026-08-29: -1.78 °F2026-08-30: -5.69 °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
2026-08-30-5.69
2026-08-29-1.78
2026-08-28-7.45
2026-08-27-9.71
2026-08-26-5.25
2026-08-25-7.66
2026-08-24-5.94
2026-08-23-3.27
2026-08-22+6.20
2026-08-21-4.28
2026-08-20-4.84
2026-08-19-6.57
2026-08-18-5.18
2026-08-17-7.80
2026-08-16-1.34
2026-08-15-11.09
2026-08-14-0.87
2026-08-13-2.02
2026-08-12-2.14
2026-08-11-0.90
2026-08-10-2.74
2026-08-09-6.36
2026-08-08-5.72
2026-08-07-3.48
2026-08-06-1.24

Error distribution

Distribution of the signed daily error in °F for GraphCast (IFS init) at KDCA, lead day 5-20 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: 1 day-10 to -8 °F: 1 day-8 to -6 °F: 5 days-6 to -4 °F: 9 days-4 to -2 °F: 5 days-2 to 0 °F: 6 days0 to 2 °F: 0 days2 to 4 °F: 1 day4 to 6 °F: 0 days6 to 8 °F: 2 days8 to 10 °F: 0 days10 to 12 °F: 0 days12 to 14 °F: 1 day14 to 16 °F: 0 days16 to 18 °F: 0 days18 to 20 °F: 0 daysdashed: P50 |e| 5.17 · P90 |e| 7.8 °F-200+20 °Fn = 31 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
-12.00-10.001
-10.00-8.001
-8.00-6.005
-6.00-4.009
-4.00-2.005
-2.00+0.006
+0.00+2.000
+2.00+4.001
+4.00+6.000
+6.00+8.002
+8.00+10.000
+10.00+12.000
+12.00+14.001
+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
2026-08254.78 -4.29
2026-0165.69 +2.02

Availability

ModelScored period DaysCoverage
GraphCast (IFS init)2026-01-06 → 2026-08-30 31
GraphCast (IFS init)2026-01-06 → 2026-08-30 31
GraphCast (IFS init)2026-01-06 → 2026-08-30 30
GraphCast (IFS init)2026-01-06 → 2026-08-30 30

Compared with other models

Paired bootstrap on the days both models cover (90d, 00Z, bilinear, daily maximum). Negative means GraphCast (IFS init) has the lower MAE. "Distinguishable" means the 95 % interval excludes zero.

Other modelCommon days MAE difference °FDistinguishable
ECMWF AIFS Single 25 +1.24 [0.84, 1.78] yes
NCEP GFS 25 +0.44 [-0.54, 1.20] no
ECMWF IFS HRES 18 +1.04 [-0.55, 2.41] no
Persistence (baseline) 25 -0.06 [-1.29, 1.41] no

Cite this page

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

LongCastCheck (2026). Station-level verification of raw weather-model 2 m temperature forecasts: KDCA (Washington Reagan), model graphcast_ifs, 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/graphcast_ifs/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