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 3

KORD · aifs_single · lead 3

Target day = initialization date + 3 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
tmax00Zbilinear30d27 1 QC3.66 [2.64, 4.73]2.22-3.20 [-4.54, -1.87]4.31 [2.99, 5.50]11% [3%, 18%]26%44%-0.20+0.292026-08-04 → 2026-08-30
tmax00Zbilinear90d27 1 QC3.66 [2.53, 4.87]2.22-3.20 [-4.75, -1.69]4.31 [2.82, 5.63]11% [0%, 20%]26%44%-0.20+0.292026-08-04 → 2026-08-30
tmax00Zbilinear365d27 1 QC3.66 [2.47, 4.84]2.22-3.20 [-4.72, -1.60]4.31 [2.76, 5.59]11% [0%, 20%]26%44%-0.20+0.292026-08-04 → 2026-08-30
tmax00Zbilinearall27 1 QC3.66 [2.46, 4.85]2.22-3.20 [-4.73, -1.56]4.31 [2.70, 5.68]11% [0%, 19%]26%44%-0.20+0.292026-08-04 → 2026-08-30
tmax00Znearest30d27 1 QC3.33 [2.30, 4.49]2.23-2.75 [-4.19, -1.36]4.03 [2.66, 5.30]11% [3%, 18%]26%52%-0.10+0.292026-08-04 → 2026-08-30
tmax00Znearest90d27 1 QC3.33 [2.20, 4.60]2.23-2.75 [-4.36, -1.16]4.03 [2.49, 5.44]11% [0%, 20%]26%52%-0.10+0.292026-08-04 → 2026-08-30
tmax00Znearest365d27 1 QC3.33 [2.19, 4.60]2.23-2.75 [-4.36, -1.03]4.03 [2.50, 5.38]11% [0%, 20%]26%52%-0.10+0.292026-08-04 → 2026-08-30
tmax00Znearestall27 1 QC3.33 [2.18, 4.65]2.23-2.75 [-4.40, -1.04]4.03 [2.45, 5.46]11% [0%, 19%]26%52%-0.10+0.292026-08-04 → 2026-08-30
tmax12Zbilinear30d27 1 QC3.46 [2.47, 4.43]2.02-3.26 [-4.37, -2.14]4.20 [3.02, 5.29]22% [10%, 36%]22%44%-0.14+0.352026-08-04 → 2026-08-30
tmax12Zbilinear90d27 1 QC3.46 [2.38, 4.63]2.02-3.26 [-4.60, -2.06]4.20 [2.90, 5.44]22% [8%, 40%]22%44%-0.14+0.352026-08-04 → 2026-08-30
tmax12Zbilinear365d27 1 QC3.46 [2.26, 4.55]2.02-3.26 [-4.55, -1.97]4.20 [2.83, 5.37]22% [6%, 44%]22%44%-0.14+0.352026-08-04 → 2026-08-30
tmax12Zbilinearall27 1 QC3.46 [2.31, 4.61]2.02-3.26 [-4.59, -1.94]4.20 [2.75, 5.47]22% [0%, 42%]22%44%-0.14+0.352026-08-04 → 2026-08-30
tmax12Znearest30d27 1 QC3.11 [2.15, 4.11]2.05-2.81 [-4.00, -1.66]3.90 [2.64, 5.06]22% [10%, 36%]26%52%-0.02+0.342026-08-04 → 2026-08-30
tmax12Znearest90d27 1 QC3.11 [2.03, 4.31]2.05-2.81 [-4.23, -1.56]3.90 [2.53, 5.17]22% [8%, 40%]26%52%-0.02+0.342026-08-04 → 2026-08-30
tmax12Znearest365d27 1 QC3.11 [1.97, 4.25]2.05-2.81 [-4.17, -1.46]3.90 [2.47, 5.17]22% [6%, 44%]26%52%-0.02+0.342026-08-04 → 2026-08-30
tmax12Znearestall27 1 QC3.11 [1.96, 4.27]2.05-2.81 [-4.23, -1.43]3.90 [2.41, 5.27]22% [0%, 42%]26%52%-0.02+0.342026-08-04 → 2026-08-30
tmin00Zbilinear30d27 1 QC1.61 [1.37, 1.82]1.60+0.17 [-0.90, 1.08]2.03 [1.76, 2.30]41% [30%, 55%]67%81%+0.58+0.592026-08-04 → 2026-08-30
tmin00Zbilinear90d27 1 QC1.61 [1.31, 1.83]1.60+0.17 [-1.06, 1.12]2.03 [1.72, 2.34]41% [29%, 58%]67%81%+0.58+0.592026-08-04 → 2026-08-30
tmin00Zbilinear365d27 1 QC1.61 [1.25, 1.86]1.60+0.17 [-1.20, 1.14]2.03 [1.67, 2.35]41% [28%, 58%]67%81%+0.58+0.592026-08-04 → 2026-08-30
tmin00Zbilinearall27 1 QC1.61 [1.26, 1.90]1.60+0.17 [-1.15, 1.07]2.03 [1.70, 2.36]41% [29%, 59%]67%81%+0.58+0.592026-08-04 → 2026-08-30
tmin00Znearest30d27 1 QC1.70 [1.42, 2.04]1.68-0.47 [-1.66, 0.50]2.15 [1.81, 2.53]41% [30%, 55%]63%81%+0.56+0.572026-08-04 → 2026-08-30
tmin00Znearest90d27 1 QC1.70 [1.37, 2.08]1.68-0.47 [-1.85, 0.52]2.15 [1.69, 2.58]41% [29%, 58%]63%81%+0.56+0.572026-08-04 → 2026-08-30
tmin00Znearest365d27 1 QC1.70 [1.35, 2.08]1.68-0.47 [-1.94, 0.58]2.15 [1.70, 2.58]41% [28%, 58%]63%81%+0.56+0.572026-08-04 → 2026-08-30
tmin00Znearestall27 1 QC1.70 [1.34, 2.08]1.68-0.47 [-1.91, 0.50]2.15 [1.69, 2.59]41% [29%, 59%]63%81%+0.56+0.572026-08-04 → 2026-08-30
tmin12Zbilinear30d27 1 QC1.55 [1.30, 1.78]1.53+0.18 [-0.84, 0.97]1.96 [1.62, 2.28]48% [38%, 58%]67%85%+0.60+0.602026-08-04 → 2026-08-30
tmin12Zbilinear90d27 1 QC1.55 [1.28, 1.76]1.53+0.18 [-1.00, 1.07]1.96 [1.61, 2.25]48% [38%, 61%]67%85%+0.60+0.602026-08-04 → 2026-08-30
tmin12Zbilinear365d27 1 QC1.55 [1.24, 1.76]1.53+0.18 [-1.11, 1.08]1.96 [1.55, 2.26]48% [38%, 62%]67%85%+0.60+0.602026-08-04 → 2026-08-30
tmin12Zbilinearall27 1 QC1.55 [1.25, 1.76]1.53+0.18 [-1.03, 1.01]1.96 [1.56, 2.24]48% [38%, 62%]67%85%+0.60+0.602026-08-04 → 2026-08-30
tmin12Znearest30d27 1 QC1.64 [1.32, 2.02]1.59-0.46 [-1.61, 0.44]2.07 [1.62, 2.53]41% [27%, 56%]70%89%+0.57+0.592026-08-04 → 2026-08-30
tmin12Znearest90d27 1 QC1.64 [1.28, 2.02]1.59-0.46 [-1.77, 0.52]2.07 [1.55, 2.53]41% [27%, 57%]70%89%+0.57+0.592026-08-04 → 2026-08-30
tmin12Znearest365d27 1 QC1.64 [1.26, 2.05]1.59-0.46 [-1.90, 0.51]2.07 [1.53, 2.60]41% [27%, 57%]70%89%+0.57+0.592026-08-04 → 2026-08-30
tmin12Znearestall27 1 QC1.64 [1.24, 2.03]1.59-0.46 [-1.83, 0.47]2.07 [1.52, 2.54]41% [25%, 57%]70%89%+0.57+0.592026-08-04 → 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 3, 00Z bilinear tmax+20+100-10-202026-08-04: -4.25 °F2026-08-05: -4.15 °F2026-08-06: -5.81 °F2026-08-07: -4.96 °F2026-08-08: -0.22 °F2026-08-09: -4.57 °F2026-08-10: -10.83 °F2026-08-11: -6.89 °F2026-08-12: -7.27 °F2026-08-13: -2.13 °F2026-08-14: -2.1 °F2026-08-15: +1.91 °F2026-08-16: -2.52 °F2026-08-17: -3.39 °F2026-08-18: -0.83 °F2026-08-19: -1.59 °F2026-08-20: +2.42 °F2026-08-21: -3.63 °F2026-08-22: -2.6 °F2026-08-23: -3.56 °F2026-08-24: -5.07 °F2026-08-25: -5.51 °F2026-08-26: -1.97 °F2026-08-27: -3.95 °F2026-08-28: -4.07 °F2026-08-29: -0.62 °F2026-08-30: +1.92 °F2026-08-042026-08-30°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 (27 days, newest first) · download CSV
Climatological dayError °F
2026-08-30+1.92
2026-08-29-0.62
2026-08-28-4.07
2026-08-27-3.95
2026-08-26-1.97
2026-08-25-5.51
2026-08-24-5.07
2026-08-23-3.56
2026-08-22-2.60
2026-08-21-3.63
2026-08-20+2.42
2026-08-19-1.59
2026-08-18-0.83
2026-08-17-3.39
2026-08-16-2.52
2026-08-15+1.91
2026-08-14-2.10
2026-08-13-2.13
2026-08-12-7.27
2026-08-11-6.89
2026-08-10-10.83
2026-08-09-4.57
2026-08-08-0.22
2026-08-07-4.96
2026-08-06-5.81
2026-08-05-4.15
2026-08-04-4.25

Error distribution

Distribution of the signed daily error in °F for ECMWF AIFS Single at KORD, lead day 3-20 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: 0 days-8 to -6 °F: 2 days-6 to -4 °F: 8 days-4 to -2 °F: 8 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: 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| 3.56 · P90 |e| 6.24 °F-200+20 °Fn = 27 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
-10.00-8.000
-8.00-6.002
-6.00-4.008
-4.00-2.008
-2.00+0.005
+0.00+2.002
+2.00+4.001
+4.00+6.000
+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
2026-08273.66 -3.20

Availability

ModelScored period DaysCoverage
ECMWF AIFS Single2026-08-04 → 2026-08-30 27
ECMWF AIFS Single2026-08-04 → 2026-08-30 27
ECMWF AIFS Single2026-08-04 → 2026-08-30 27
ECMWF AIFS Single2026-08-04 → 2026-08-30 27

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 27 -0.26 [-1.41, 0.65] no
GraphCast (IFS init) 25 -0.13 [-0.93, 0.41] no
ECMWF IFS HRES 22 +0.97 [-0.19, 2.78] no
Persistence (baseline) 27 +0.62 [-1.12, 2.30] no

Cite this page

ShortCastCheck, KORD aifs_single lead 3, methodology v0.2, accessed 2026-08-31, https://castcheck.zifanzhang.com/station/KORD/model/aifs_single/lead/3/

LongCastCheck (2026). Station-level verification of raw weather-model 2 m temperature forecasts: KORD (Chicago O'Hare), model aifs_single, lead day 3. 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/3/

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