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CastCheck methodology v0.2 · data through 2026-08-30

Chicago O'Hare · ECMWF IFS HRES · lead day 0

KORD · ifs_hres · lead 0

Target day = initialization date + 0 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, ifs-gpid161, 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 QC2.42 [1.71, 3.03]1.68-1.73 [-2.77, -0.42]2.75 [2.11, 3.20]25% [5%, 47%]33%58%——2026-08-01 → 2026-08-30
tmax00Zbilinear90d24 1 QC2.42 [1.69, 3.10]1.68-1.73 [-2.83, 0.00]2.75 [2.07, 3.25]25% [0%, 50%]33%58%——2026-08-01 → 2026-08-30
tmax00Zbilinear365d24 1 QC2.42 [1.62, 3.16]1.68-1.73 [-2.85, 0.01]2.75 [2.02, 3.30]25% [0%, 55%]33%58%——2026-08-01 → 2026-08-30
tmax00Zbilinearall24 1 QC2.42 [1.66, 3.14]1.68-1.73 [-2.90, 0.11]2.75 [1.98, 3.29]25% [0%, 50%]33%58%——2026-08-01 → 2026-08-30
tmax00Znearest30d24 1 QC2.30 [1.69, 2.86]1.76-1.32 [-2.51, 0.15]2.62 [1.97, 3.13]21% [4%, 38%]42%75%——2026-08-01 → 2026-08-30
tmax00Znearest90d24 1 QC2.30 [1.63, 2.98]1.76-1.32 [-2.58, 0.62]2.62 [1.87, 3.20]21% [0%, 44%]42%75%——2026-08-01 → 2026-08-30
tmax00Znearest365d24 1 QC2.30 [1.59, 3.05]1.76-1.32 [-2.59, 0.63]2.62 [1.86, 3.23]21% [0%, 46%]42%75%——2026-08-01 → 2026-08-30
tmax00Znearestall24 1 QC2.30 [1.62, 3.06]1.76-1.32 [-2.66, 0.68]2.62 [1.86, 3.24]21% [0%, 43%]42%75%——2026-08-01 → 2026-08-30
tmin00Zbilinear30d24 1 QC1.20 [0.94, 1.58]1.17+0.36 [-0.16, 0.87]1.75 [1.40, 2.28]62% [43%, 77%]75%92%——2026-08-01 → 2026-08-30
tmin00Zbilinear90d24 1 QC1.20 [0.83, 1.90]1.17+0.36 [-0.38, 1.27]1.75 [1.31, 2.59]62% [40%, 78%]75%92%——2026-08-01 → 2026-08-30
tmin00Zbilinear365d24 1 QC1.20 [0.85, 1.91]1.17+0.36 [-0.45, 1.38]1.75 [1.28, 2.50]62% [38%, 79%]75%92%——2026-08-01 → 2026-08-30
tmin00Zbilinearall24 1 QC1.20 [0.85, 1.99]1.17+0.36 [-0.33, 1.53]1.75 [1.30, 2.74]62% [36%, 79%]75%92%——2026-08-01 → 2026-08-30
tmin00Znearest30d24 1 QC1.16 [0.81, 1.61]1.13-0.19 [-0.67, 0.39]1.64 [1.15, 2.17]54% [36%, 70%]88%92%——2026-08-01 → 2026-08-30
tmin00Znearest90d24 1 QC1.16 [0.79, 1.84]1.13-0.19 [-0.84, 0.76]1.64 [1.07, 2.35]54% [33%, 70%]88%92%——2026-08-01 → 2026-08-30
tmin00Znearest365d24 1 QC1.16 [0.80, 1.75]1.13-0.19 [-0.91, 0.79]1.64 [1.06, 2.25]54% [32%, 71%]88%92%——2026-08-01 → 2026-08-30
tmin00Znearestall24 1 QC1.16 [0.79, 1.92]1.13-0.19 [-0.81, 1.04]1.64 [1.08, 2.46]54% [30%, 71%]88%92%——2026-08-01 → 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 ECMWF IFS HRES at KORD, lead day 0, 00Z bilinear tmax+5+2.50-2.5-52026-08-01: +2.07 °F2026-08-08: -2.93 °F2026-08-09: +4.69 °F2026-08-10: -3.14 °F2026-08-11: +0.14 °F2026-08-12: -0.71 °F2026-08-13: +0.84 °F2026-08-14: -1.67 °F2026-08-15: +0.56 °F2026-08-16: -1.56 °F2026-08-17: -4.15 °F2026-08-18: -2.24 °F2026-08-19: -2.24 °F2026-08-20: -3.06 °F2026-08-21: -2.07 °F2026-08-22: -4.53 °F2026-08-23: -3.48 °F2026-08-24: -2.68 °F2026-08-25: -3.6 °F2026-08-26: -3.88 °F2026-08-27: -3.17 °F2026-08-28: -3.16 °F2026-08-29: -0.74 °F2026-08-30: -0.74 °F2026-08-012026-08-30°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 (30 days, newest first) · download CSV
Climatological dayError °F
2026-08-30-0.74
2026-08-29-0.74
2026-08-28-3.16
2026-08-27-3.17
2026-08-26-3.88
2026-08-25-3.60
2026-08-24-2.68
2026-08-23-3.48
2026-08-22-4.53
2026-08-21-2.07
2026-08-20-3.06
2026-08-19-2.24
2026-08-18-2.24
2026-08-17-4.15
2026-08-16-1.56
2026-08-15+0.56
2026-08-14-1.67
2026-08-13+0.84
2026-08-12-0.71
2026-08-11+0.14
2026-08-10-3.14
2026-08-09+4.69
2026-08-08-2.93
2026-08-07—
2026-08-06—
2026-08-05—
2026-08-04—
2026-08-03—
2026-08-02—
2026-08-01+2.07

Error distribution

Distribution of the signed daily error in °F for ECMWF IFS HRES at KORD, lead day 0-5 to -4.5 °F: 1 day-4.5 to -4 °F: 1 day-4 to -3.5 °F: 2 days-3.5 to -3 °F: 5 days-3 to -2.5 °F: 2 days-2.5 to -2 °F: 3 days-2 to -1.5 °F: 2 days-1.5 to -1 °F: 0 days-1 to -0.5 °F: 3 days-0.5 to 0 °F: 0 days0 to 0.5 °F: 1 day0.5 to 1 °F: 2 days1 to 1.5 °F: 0 days1.5 to 2 °F: 0 days2 to 2.5 °F: 1 day2.5 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: 1 daydashed: P50 |e| 2.46 · P90 |e| 4.07 °F-50+5 °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
-5.00-4.501
-4.50-4.001
-4.00-3.502
-3.50-3.005
-3.00-2.502
-2.50-2.003
-2.00-1.502
-1.50-1.000
-1.00-0.503
-0.50+0.000
+0.00+0.501
+0.50+1.002
+1.00+1.500
+1.50+2.000
+2.00+2.501
+2.50+3.000
+3.00+3.500
+3.50+4.000
+4.00+4.500
+4.50+5.001

Month by month

00Z bilinear daily maximum, newest first.

Monthn MAE °FBias °F
2026-08242.42 -1.73

Availability

ModelScored period DaysCoverage
ECMWF IFS HRES2026-08-01 → 2026-08-30 24
ECMWF IFS HRES2026-08-01 → 2026-08-30 24

Compared with other models

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

Other modelCommon days MAE difference °FDistinguishable
ECMWF AIFS Single 24 -0.59 [-1.46, 0.29] no
Aurora (GFS init) 2 -4.37 [-6.47, -2.26] yes
Aurora (IFS init) 3 -1.41 [-2.02, -0.50] yes
FourCastNet v2 (GFS init) 2 -0.78 [-0.99, -0.57] yes
FourCastNet v2 (IFS init) 3 -1.82 [-1.92, -1.61] yes
NCEP GFS 24 +0.19 [-1.14, 0.88] no
GraphCast (GFS init) 2 -2.78 [-3.75, -1.81] yes
GraphCast (IFS init) 22 -0.82 [-1.73, 0.06] no
Pangu-Weather (GFS init) 2 -1.62 [-1.83, -1.41] yes
Pangu-Weather (IFS init) 3 -1.16 [-2.36, -0.12] yes

Cite this page

ShortCastCheck, KORD ifs_hres lead 0, methodology v0.2, accessed 2026-08-31, https://castcheck.zifanzhang.com/station/KORD/model/ifs_hres/lead/0/

LongCastCheck (2026). Station-level verification of raw weather-model 2 m temperature forecasts: KORD (Chicago O'Hare), model ifs_hres, lead day 0. Methodology version 0.2, schema version 0.1, data through 2026-08-30. Accessed 2026-08-31. https://castcheck.zifanzhang.com/station/KORD/model/ifs_hres/lead/0/

Accessed2026-08-31 (data through 2026-08-30; page built 2026-08-31T03:52:06+00:00)

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