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

Chicago O'Hare · ECMWF AIFS Single · lead day 6

KORD · aifs_single · 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, aifs-single-gpid5, 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 QC4.24 [3.34, 5.18]2.65-3.50 [-4.50, -2.40]5.12 [3.86, 6.21]8% [0%, 19%]21%33%-0.26+0.212026-08-07 → 2026-08-30
tmax00Zbilinear90d24 1 QC4.24 [3.34, 5.46]2.65-3.50 [-4.60, -2.24]5.12 [3.86, 6.48]8% [0%, 22%]21%33%-0.26+0.212026-08-07 → 2026-08-30
tmax00Zbilinear365d24 1 QC4.24 [3.29, 5.45]2.65-3.50 [-4.56, -2.10]5.12 [3.76, 6.36]8% [0%, 22%]21%33%-0.26+0.212026-08-07 → 2026-08-30
tmax00Zbilinearall24 1 QC4.24 [3.19, 5.45]2.65-3.50 [-4.50, -1.94]5.12 [3.58, 6.29]8% [0%, 21%]21%33%-0.26+0.212026-08-07 → 2026-08-30
tmax00Znearest30d24 1 QC3.94 [3.09, 4.86]2.65-3.01 [-3.94, -1.92]4.81 [3.51, 5.94]8% [0%, 19%]21%38%-0.17+0.212026-08-07 → 2026-08-30
tmax00Znearest90d24 1 QC3.94 [3.10, 5.14]2.65-3.01 [-4.08, -1.75]4.81 [3.54, 6.15]8% [0%, 22%]21%38%-0.17+0.212026-08-07 → 2026-08-30
tmax00Znearest365d24 1 QC3.94 [3.04, 5.08]2.65-3.01 [-4.02, -1.59]4.81 [3.43, 6.03]8% [0%, 22%]21%38%-0.17+0.212026-08-07 → 2026-08-30
tmax00Znearestall24 1 QC3.94 [2.90, 5.11]2.65-3.01 [-3.98, -1.41]4.81 [3.29, 5.98]8% [0%, 21%]21%38%-0.17+0.212026-08-07 → 2026-08-30
tmax12Zbilinear30d24 1 QC3.83 [3.28, 4.48]2.21-3.29 [-3.87, -2.44]4.46 [3.74, 5.20]4% [0%, 12%]21%38%-0.13+0.342026-08-07 → 2026-08-30
tmax12Zbilinear90d24 1 QC3.83 [3.26, 4.71]2.21-3.29 [-3.95, -2.29]4.46 [3.69, 5.43]4% [0%, 12%]21%38%-0.13+0.342026-08-07 → 2026-08-30
tmax12Zbilinear365d24 1 QC3.83 [3.20, 4.60]2.21-3.29 [-3.89, -2.24]4.46 [3.64, 5.33]4% [0%, 14%]21%38%-0.13+0.342026-08-07 → 2026-08-30
tmax12Zbilinearall24 1 QC3.83 [3.17, 4.64]2.21-3.29 [-3.94, -2.07]4.46 [3.57, 5.39]4% [0%, 14%]21%38%-0.13+0.342026-08-07 → 2026-08-30
tmax12Znearest30d24 1 QC3.51 [2.94, 4.25]2.22-2.81 [-3.40, -1.93]4.15 [3.41, 4.95]4% [0%, 12%]38%50%-0.04+0.342026-08-07 → 2026-08-30
tmax12Znearest90d24 1 QC3.51 [2.93, 4.46]2.22-2.81 [-3.46, -1.77]4.15 [3.39, 5.15]4% [0%, 12%]38%50%-0.04+0.342026-08-07 → 2026-08-30
tmax12Znearest365d24 1 QC3.51 [2.89, 4.40]2.22-2.81 [-3.43, -1.71]4.15 [3.28, 5.10]4% [0%, 14%]38%50%-0.04+0.342026-08-07 → 2026-08-30
tmax12Znearestall24 1 QC3.51 [2.85, 4.54]2.22-2.81 [-3.47, -1.52]4.15 [3.23, 5.16]4% [0%, 14%]38%50%-0.04+0.342026-08-07 → 2026-08-30
tmin00Zbilinear30d24 1 QC1.93 [1.31, 2.49]2.01+0.32 [-0.90, 1.35]2.59 [1.76, 3.32]42% [23%, 62%]62%79%+0.57+0.552026-08-07 → 2026-08-30
tmin00Zbilinear90d24 1 QC1.93 [1.24, 2.51]2.01+0.32 [-1.35, 1.48]2.59 [1.64, 3.41]42% [21%, 64%]62%79%+0.57+0.552026-08-07 → 2026-08-30
tmin00Zbilinear365d24 1 QC1.93 [1.22, 2.58]2.01+0.32 [-1.40, 1.47]2.59 [1.61, 3.49]42% [19%, 64%]62%79%+0.57+0.552026-08-07 → 2026-08-30
tmin00Zbilinearall24 1 QC1.93 [1.15, 2.57]2.01+0.32 [-1.40, 1.50]2.59 [1.55, 3.44]42% [19%, 67%]62%79%+0.57+0.552026-08-07 → 2026-08-30
tmin00Znearest30d24 1 QC2.22 [1.83, 2.61]2.14-0.33 [-1.66, 0.83]2.73 [2.15, 3.36]17% [8%, 28%]50%79%+0.50+0.522026-08-07 → 2026-08-30
tmin00Znearest90d24 1 QC2.22 [1.79, 2.67]2.14-0.33 [-2.11, 0.95]2.73 [2.11, 3.41]17% [7%, 30%]50%79%+0.50+0.522026-08-07 → 2026-08-30
tmin00Znearest365d24 1 QC2.22 [1.82, 2.71]2.14-0.33 [-2.13, 0.96]2.73 [2.13, 3.47]17% [7%, 32%]50%79%+0.50+0.522026-08-07 → 2026-08-30
tmin00Znearestall24 1 QC2.22 [1.75, 2.68]2.14-0.33 [-2.12, 1.02]2.73 [2.02, 3.45]17% [8%, 33%]50%79%+0.50+0.522026-08-07 → 2026-08-30
tmin12Zbilinear30d24 1 QC2.26 [1.30, 3.16]2.23+0.57 [-0.62, 1.63]3.04 [1.83, 3.96]38% [12%, 64%]54%71%+0.49+0.502026-08-07 → 2026-08-30
tmin12Zbilinear90d24 1 QC2.26 [1.17, 3.13]2.23+0.57 [-0.91, 1.90]3.04 [1.65, 4.02]38% [12%, 68%]54%71%+0.49+0.502026-08-07 → 2026-08-30
tmin12Zbilinear365d24 1 QC2.26 [1.10, 3.24]2.23+0.57 [-0.96, 1.83]3.04 [1.56, 4.12]38% [10%, 70%]54%71%+0.49+0.502026-08-07 → 2026-08-30
tmin12Zbilinearall24 1 QC2.26 [1.00, 3.14]2.23+0.57 [-0.99, 1.85]3.04 [1.44, 4.05]38% [11%, 71%]54%71%+0.49+0.502026-08-07 → 2026-08-30
tmin12Znearest30d24 1 QC2.38 [1.44, 3.22]2.37-0.10 [-1.35, 1.09]3.14 [2.09, 3.93]33% [7%, 63%]50%71%+0.47+0.472026-08-07 → 2026-08-30
tmin12Znearest90d24 1 QC2.38 [1.39, 3.19]2.37-0.10 [-1.74, 1.36]3.14 [1.97, 4.00]33% [7%, 65%]50%71%+0.47+0.472026-08-07 → 2026-08-30
tmin12Znearest365d24 1 QC2.38 [1.25, 3.34]2.37-0.10 [-1.79, 1.26]3.14 [1.75, 4.13]33% [5%, 67%]50%71%+0.47+0.472026-08-07 → 2026-08-30
tmin12Znearestall24 1 QC2.38 [1.13, 3.24]2.37-0.10 [-1.80, 1.33]3.14 [1.71, 4.03]33% [4%, 71%]50%71%+0.47+0.472026-08-07 → 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 ECMWF AIFS Single at KORD, lead day 6, 00Z bilinear tmax+20+100-10-202026-08-07: -5.37 °F2026-08-08: -0.59 °F2026-08-09: +1.37 °F2026-08-10: -11.91 °F2026-08-11: -2.27 °F2026-08-12: -5.69 °F2026-08-13: -0.17 °F2026-08-14: -3.51 °F2026-08-15: +1.85 °F2026-08-16: -3.91 °F2026-08-17: -3.77 °F2026-08-18: -3.45 °F2026-08-19: +1.46 °F2026-08-20: -7.33 °F2026-08-21: -3.83 °F2026-08-22: -2.73 °F2026-08-23: -4.33 °F2026-08-24: -5.14 °F2026-08-25: -4.11 °F2026-08-26: -3.37 °F2026-08-27: -6.68 °F2026-08-28: -11.78 °F2026-08-29: -2.92 °F2026-08-30: +4.14 °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+4.14
2026-08-29-2.92
2026-08-28-11.78
2026-08-27-6.68
2026-08-26-3.37
2026-08-25-4.11
2026-08-24-5.14
2026-08-23-4.33
2026-08-22-2.73
2026-08-21-3.83
2026-08-20-7.33
2026-08-19+1.46
2026-08-18-3.45
2026-08-17-3.77
2026-08-16-3.91
2026-08-15+1.85
2026-08-14-3.51
2026-08-13-0.17
2026-08-12-5.69
2026-08-11-2.27
2026-08-10-11.91
2026-08-09+1.37
2026-08-08-0.59
2026-08-07-5.37

Error distribution

Distribution of the signed daily error in °F for ECMWF AIFS Single at KORD, 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: 0 days-12 to -10 °F: 2 days-10 to -8 °F: 0 days-8 to -6 °F: 2 days-6 to -4 °F: 5 days-4 to -2 °F: 9 days-2 to 0 °F: 2 days0 to 2 °F: 3 days2 to 4 °F: 0 days4 to 6 °F: 1 day6 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| 3.8 · P90 |e| 7.14 °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
-14.00-12.000
-12.00-10.002
-10.00-8.000
-8.00-6.002
-6.00-4.005
-4.00-2.009
-2.00+0.002
+0.00+2.003
+2.00+4.000
+4.00+6.001
+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
2026-08244.24 -3.50

Availability

ModelScored period DaysCoverage
ECMWF AIFS Single2026-08-07 → 2026-08-30 24
ECMWF AIFS Single2026-08-07 → 2026-08-30 24
ECMWF AIFS Single2026-08-07 → 2026-08-30 24
ECMWF AIFS Single2026-08-07 → 2026-08-30 24

Compared with other models

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

Other modelCommon days MAE difference °FDistinguishable
NCEP GFS 24 +1.40 [0.07, 2.94] yes
GraphCast (IFS init) 24 +0.14 [-0.75, 1.37] no
ECMWF IFS HRES 19 +0.76 [0.00, 1.97] yes
Persistence (baseline) 24 +0.86 [-1.36, 2.31] no

Cite this page

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

LongCastCheck (2026). Station-level verification of raw weather-model 2 m temperature forecasts: KORD (Chicago O'Hare), model aifs_single, 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/KORD/model/aifs_single/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