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

Chicago O'Hare · ECMWF AIFS Single · lead day 8

KORD · aifs_single · lead 8

Target day = initialization date + 8 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
tmax00Zbilinear30d22 1 QC5.53 [4.21, 6.90]3.79-4.54 [-5.92, -3.20]6.43 [5.23, 7.68]14% [0%, 28%]18%23%-0.47-0.002026-08-09 → 2026-08-30
tmax00Zbilinear90d22 1 QC5.53 [4.19, 7.37]3.79-4.54 [-6.20, -3.09]6.43 [5.16, 8.03]14% [0%, 29%]18%23%-0.47-0.002026-08-09 → 2026-08-30
tmax00Zbilinear365d22 1 QC5.53 [4.08, 7.35]3.79-4.54 [-6.27, -3.10]6.43 [5.16, 7.98]14% [0%, 31%]18%23%-0.47-0.002026-08-09 → 2026-08-30
tmax00Zbilinearall22 1 QC5.53 [4.08, 7.34]3.79-4.54 [-6.24, -3.00]6.43 [5.16, 8.00]14% [0%, 29%]18%23%-0.47-0.002026-08-09 → 2026-08-30
tmax00Znearest30d22 1 QC5.44 [4.24, 6.74]3.87-4.14 [-5.44, -2.81]6.23 [5.14, 7.39]14% [0%, 28%]18%18%-0.44-0.032026-08-09 → 2026-08-30
tmax00Znearest90d22 1 QC5.44 [4.17, 7.09]3.87-4.14 [-5.62, -2.71]6.23 [5.03, 7.66]14% [0%, 29%]18%18%-0.44-0.032026-08-09 → 2026-08-30
tmax00Znearest365d22 1 QC5.44 [4.13, 7.12]3.87-4.14 [-5.68, -2.71]6.23 [5.03, 7.61]14% [0%, 31%]18%18%-0.44-0.032026-08-09 → 2026-08-30
tmax00Znearestall22 1 QC5.44 [4.13, 7.05]3.87-4.14 [-5.66, -2.59]6.23 [5.01, 7.64]14% [0%, 29%]18%18%-0.44-0.032026-08-09 → 2026-08-30
tmax12Zbilinear30d22 1 QC5.06 [3.82, 6.48]2.78-4.58 [-6.34, -3.00]5.84 [4.17, 7.39]5% [0%, 14%]9%18%-0.34+0.262026-08-09 → 2026-08-30
tmax12Zbilinear90d22 1 QC5.06 [3.63, 6.75]2.78-4.58 [-6.75, -2.81]5.84 [3.94, 7.75]5% [0%, 14%]9%18%-0.34+0.262026-08-09 → 2026-08-30
tmax12Zbilinear365d22 1 QC5.06 [3.55, 6.79]2.78-4.58 [-6.79, -2.79]5.84 [3.72, 7.67]5% [0%, 14%]9%18%-0.34+0.262026-08-09 → 2026-08-30
tmax12Zbilinearall22 1 QC5.06 [3.63, 6.83]2.78-4.58 [-6.83, -2.79]5.84 [3.90, 7.76]5% [0%, 14%]9%18%-0.34+0.262026-08-09 → 2026-08-30
tmax12Znearest30d22 1 QC4.72 [3.53, 6.04]2.78-4.09 [-5.77, -2.57]5.48 [3.91, 6.91]5% [0%, 14%]9%32%-0.25+0.262026-08-09 → 2026-08-30
tmax12Znearest90d22 1 QC4.72 [3.32, 6.32]2.78-4.09 [-6.16, -2.34]5.48 [3.68, 7.24]5% [0%, 14%]9%32%-0.25+0.262026-08-09 → 2026-08-30
tmax12Znearest365d22 1 QC4.72 [3.22, 6.30]2.78-4.09 [-6.19, -2.34]5.48 [3.41, 7.17]5% [0%, 14%]9%32%-0.25+0.262026-08-09 → 2026-08-30
tmax12Znearestall22 1 QC4.72 [3.29, 6.34]2.78-4.09 [-6.26, -2.34]5.48 [3.53, 7.25]5% [0%, 14%]9%32%-0.25+0.262026-08-09 → 2026-08-30
tmin00Zbilinear30d22 1 QC2.83 [1.99, 4.05]2.85-0.27 [-2.64, 1.68]3.74 [2.57, 5.09]32% [16%, 44%]50%59%+0.38+0.402026-08-09 → 2026-08-30
tmin00Zbilinear90d22 1 QC2.83 [1.95, 4.49]2.85-0.27 [-3.36, 1.89]3.74 [2.53, 5.46]32% [12%, 43%]50%59%+0.38+0.402026-08-09 → 2026-08-30
tmin00Zbilinear365d22 1 QC2.83 [1.98, 4.39]2.85-0.27 [-3.22, 1.97]3.74 [2.53, 5.48]32% [11%, 43%]50%59%+0.38+0.402026-08-09 → 2026-08-30
tmin00Zbilinearall22 1 QC2.83 [1.89, 4.42]2.85-0.27 [-3.62, 1.80]3.74 [2.40, 5.59]32% [7%, 44%]50%59%+0.38+0.402026-08-09 → 2026-08-30
tmin00Znearest30d22 1 QC2.95 [1.94, 4.46]2.92-0.95 [-3.39, 1.06]3.94 [2.59, 5.57]23% [7%, 38%]50%59%+0.35+0.392026-08-09 → 2026-08-30
tmin00Znearest90d22 1 QC2.95 [1.94, 4.81]2.92-0.95 [-4.18, 1.26]3.94 [2.54, 6.05]23% [0%, 39%]50%59%+0.35+0.392026-08-09 → 2026-08-30
tmin00Znearest365d22 1 QC2.95 [1.88, 4.84]2.92-0.95 [-4.05, 1.31]3.94 [2.43, 6.05]23% [0%, 43%]50%59%+0.35+0.392026-08-09 → 2026-08-30
tmin00Znearestall22 1 QC2.95 [1.79, 4.83]2.92-0.95 [-4.43, 1.18]3.94 [2.40, 6.09]23% [0%, 43%]50%59%+0.35+0.392026-08-09 → 2026-08-30
tmin12Zbilinear30d22 1 QC2.91 [2.05, 4.04]2.89-0.70 [-2.84, 0.85]3.77 [2.66, 4.78]32% [18%, 44%]50%55%+0.36+0.392026-08-09 → 2026-08-30
tmin12Zbilinear90d22 1 QC2.91 [1.90, 4.37]2.89-0.70 [-3.60, 1.01]3.77 [2.52, 5.16]32% [14%, 47%]50%55%+0.36+0.392026-08-09 → 2026-08-30
tmin12Zbilinear365d22 1 QC2.91 [1.90, 4.29]2.89-0.70 [-3.55, 1.13]3.77 [2.51, 5.01]32% [12%, 46%]50%55%+0.36+0.392026-08-09 → 2026-08-30
tmin12Zbilinearall22 1 QC2.91 [1.91, 4.34]2.89-0.70 [-4.01, 0.96]3.77 [2.53, 5.15]32% [14%, 46%]50%55%+0.36+0.392026-08-09 → 2026-08-30
tmin12Znearest30d22 1 QC3.24 [2.21, 4.55]2.99-1.41 [-3.65, 0.27]4.13 [2.85, 5.38]23% [9%, 35%]45%59%+0.29+0.372026-08-09 → 2026-08-30
tmin12Znearest90d22 1 QC3.24 [2.07, 4.92]2.99-1.41 [-4.42, 0.46]4.13 [2.73, 5.79]23% [6%, 37%]45%59%+0.29+0.372026-08-09 → 2026-08-30
tmin12Znearest365d22 1 QC3.24 [2.09, 4.89]2.99-1.41 [-4.39, 0.51]4.13 [2.74, 5.69]23% [0%, 38%]45%59%+0.29+0.372026-08-09 → 2026-08-30
tmin12Znearestall22 1 QC3.24 [2.10, 4.91]2.99-1.41 [-4.85, 0.44]4.13 [2.76, 5.84]23% [6%, 38%]45%59%+0.29+0.372026-08-09 → 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 8, 00Z bilinear tmax+20+100-10-202026-08-09: -0.02 °F2026-08-10: -9.72 °F2026-08-11: -3.88 °F2026-08-12: -3.68 °F2026-08-13: +3.16 °F2026-08-14: -5.26 °F2026-08-15: -0.81 °F2026-08-16: -9.63 °F2026-08-17: -5.21 °F2026-08-18: -7.73 °F2026-08-19: +0.29 °F2026-08-20: -1.68 °F2026-08-21: -6.94 °F2026-08-22: -6.85 °F2026-08-23: +5.19 °F2026-08-24: -7.23 °F2026-08-25: -5.51 °F2026-08-26: -8.85 °F2026-08-27: -5.72 °F2026-08-28: -12 °F2026-08-29: -9.99 °F2026-08-30: +2.29 °F2026-08-092026-08-30°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 (22 days, newest first) · download CSV
Climatological dayError °F
2026-08-30+2.29
2026-08-29-9.99
2026-08-28-12.00
2026-08-27-5.72
2026-08-26-8.85
2026-08-25-5.51
2026-08-24-7.23
2026-08-23+5.19
2026-08-22-6.85
2026-08-21-6.94
2026-08-20-1.68
2026-08-19+0.29
2026-08-18-7.73
2026-08-17-5.21
2026-08-16-9.63
2026-08-15-0.81
2026-08-14-5.26
2026-08-13+3.16
2026-08-12-3.68
2026-08-11-3.88
2026-08-10-9.72
2026-08-09-0.02

Error distribution

Distribution of the signed daily error in °F for ECMWF AIFS Single at KORD, lead day 8-20 to -18 °F: 0 days-18 to -16 °F: 0 days-16 to -14 °F: 0 days-14 to -12 °F: 1 day-12 to -10 °F: 0 days-10 to -8 °F: 4 days-8 to -6 °F: 4 days-6 to -4 °F: 4 days-4 to -2 °F: 2 days-2 to 0 °F: 3 days0 to 2 °F: 1 day2 to 4 °F: 2 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| 5.38 · P90 |e| 9.71 °F-200+20 °Fn = 22 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
-14.00-12.001
-12.00-10.000
-10.00-8.004
-8.00-6.004
-6.00-4.004
-4.00-2.002
-2.00+0.003
+0.00+2.001
+2.00+4.002
+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
2026-08225.53 -4.54

Availability

ModelScored period DaysCoverage
ECMWF AIFS Single2026-08-09 → 2026-08-30 22
ECMWF AIFS Single2026-08-09 → 2026-08-30 22
ECMWF AIFS Single2026-08-09 → 2026-08-30 22
ECMWF AIFS Single2026-08-09 → 2026-08-30 22

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 22 +0.88 [-0.97, 3.12] no
GraphCast (IFS init) 22 +0.96 [-0.41, 2.26] no
ECMWF IFS HRES 17 +0.52 [-1.52, 2.58] no
Persistence (baseline) 22 +1.76 [-1.51, 4.74] no

Cite this page

ShortCastCheck, KORD aifs_single lead 8, methodology v0.2, accessed 2026-08-31, https://castcheck.zifanzhang.com/station/KORD/model/aifs_single/lead/8/

LongCastCheck (2026). Station-level verification of raw weather-model 2 m temperature forecasts: KORD (Chicago O'Hare), model aifs_single, lead day 8. 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/8/

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