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

San Francisco Intl · ECMWF AIFS Single · lead day 0

KSFO · aifs_single · 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, 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
tmax00Zbilinear30d30 1 QC4.58 [3.66, 5.59]2.46-4.49 [-5.52, -3.60]5.38 [4.43, 6.29]20% [7%, 33%]23%33%——2026-08-01 → 2026-08-30
tmax00Zbilinear90d30 1 QC4.58 [3.62, 5.66]2.46-4.49 [-5.63, -3.52]5.38 [4.31, 6.35]20% [7%, 33%]23%33%——2026-08-01 → 2026-08-30
tmax00Zbilinear365d30 1 QC4.58 [3.59, 5.73]2.46-4.49 [-5.68, -3.48]5.38 [4.29, 6.45]20% [6%, 35%]23%33%——2026-08-01 → 2026-08-30
tmax00Zbilinearall30 1 QC4.58 [3.62, 5.79]2.46-4.49 [-5.75, -3.53]5.38 [4.37, 6.43]20% [5%, 33%]23%33%——2026-08-01 → 2026-08-30
tmax00Znearest30d30 1 QC2.75 [2.00, 3.56]2.62-0.84 [-2.10, 0.38]3.30 [2.48, 4.09]27% [10%, 43%]40%57%——2026-08-01 → 2026-08-30
tmax00Znearest90d30 1 QC2.75 [1.93, 3.60]2.62-0.84 [-2.20, 0.40]3.30 [2.43, 4.10]27% [7%, 44%]40%57%——2026-08-01 → 2026-08-30
tmax00Znearest365d30 1 QC2.75 [1.86, 3.71]2.62-0.84 [-2.43, 0.40]3.30 [2.35, 4.19]27% [5%, 45%]40%57%——2026-08-01 → 2026-08-30
tmax00Znearestall30 1 QC2.75 [1.95, 3.69]2.62-0.84 [-2.32, 0.47]3.30 [2.40, 4.15]27% [6%, 43%]40%57%——2026-08-01 → 2026-08-30
tmin00Zbilinear30d30 1 QC0.87 [0.56, 1.19]0.77-0.43 [-0.72, -0.08]1.11 [0.77, 1.39]60% [43%, 77%]97%100%——2026-08-01 → 2026-08-30
tmin00Zbilinear90d30 1 QC0.87 [0.55, 1.25]0.77-0.43 [-0.79, 0.02]1.11 [0.77, 1.43]60% [42%, 76%]97%100%——2026-08-01 → 2026-08-30
tmin00Zbilinear365d30 1 QC0.87 [0.55, 1.27]0.77-0.43 [-0.79, 0.04]1.11 [0.75, 1.47]60% [39%, 75%]97%100%——2026-08-01 → 2026-08-30
tmin00Zbilinearall30 1 QC0.87 [0.54, 1.22]0.77-0.43 [-0.83, -0.02]1.11 [0.73, 1.46]60% [40%, 76%]97%100%——2026-08-01 → 2026-08-30
tmin00Znearest30d30 1 QC1.04 [0.76, 1.34]1.04-0.09 [-0.51, 0.37]1.28 [0.89, 1.60]57% [40%, 77%]93%97%——2026-08-01 → 2026-08-30
tmin00Znearest90d30 1 QC1.04 [0.77, 1.42]1.04-0.09 [-0.57, 0.38]1.28 [0.89, 1.69]57% [36%, 80%]93%97%——2026-08-01 → 2026-08-30
tmin00Znearest365d30 1 QC1.04 [0.75, 1.46]1.04-0.09 [-0.61, 0.40]1.28 [0.88, 1.70]57% [33%, 77%]93%97%——2026-08-01 → 2026-08-30
tmin00Znearestall30 1 QC1.04 [0.74, 1.40]1.04-0.09 [-0.64, 0.39]1.28 [0.86, 1.66]57% [35%, 79%]93%97%——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 AIFS Single at KSFO, lead day 0, 00Z bilinear tmax+20+100-10-202026-08-01: -2.68 °F2026-08-02: -8.71 °F2026-08-03: -8.07 °F2026-08-04: -5.21 °F2026-08-05: -3.95 °F2026-08-06: -4.43 °F2026-08-07: -0.99 °F2026-08-08: -0.01 °F2026-08-09: -0.74 °F2026-08-10: -5.68 °F2026-08-11: -10.17 °F2026-08-12: -9.06 °F2026-08-13: -8.11 °F2026-08-14: -6.1 °F2026-08-15: -3.94 °F2026-08-16: -3.9 °F2026-08-17: -5.95 °F2026-08-18: -2.51 °F2026-08-19: -0.51 °F2026-08-20: -3.76 °F2026-08-21: -2.64 °F2026-08-22: -1.78 °F2026-08-23: -8.2 °F2026-08-24: -6.88 °F2026-08-25: +0.9 °F2026-08-26: -6.36 °F2026-08-27: -4.4 °F2026-08-28: +0.47 °F2026-08-29: -5.98 °F2026-08-30: -5.31 °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
2026-08-30-5.31
2026-08-29-5.98
2026-08-28+0.47
2026-08-27-4.40
2026-08-26-6.36
2026-08-25+0.90
2026-08-24-6.88
2026-08-23-8.20
2026-08-22-1.78
2026-08-21-2.64
2026-08-20-3.76
2026-08-19-0.51
2026-08-18-2.51
2026-08-17-5.95
2026-08-16-3.90
2026-08-15-3.94
2026-08-14-6.10
2026-08-13-8.11
2026-08-12-9.06
2026-08-11-10.17
2026-08-10-5.68
2026-08-09-0.74
2026-08-08-0.01
2026-08-07-0.99
2026-08-06-4.43
2026-08-05-3.95
2026-08-04-5.21
2026-08-03-8.07
2026-08-02-8.71
2026-08-01-2.68

Error distribution

Distribution of the signed daily error in °F for ECMWF AIFS Single at KSFO, lead day 0-20 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: 5 days-8 to -6 °F: 3 days-6 to -4 °F: 7 days-4 to -2 °F: 7 days-2 to 0 °F: 5 days0 to 2 °F: 2 days2 to 4 °F: 0 days4 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| 4.41 · P90 |e| 8.25 °F-200+20 °Fn = 30 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
-10.00-8.005
-8.00-6.003
-6.00-4.007
-4.00-2.007
-2.00+0.005
+0.00+2.002
+2.00+4.000
+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
2026-08304.58 -4.49

Availability

ModelScored period DaysCoverage
ECMWF AIFS Single2026-08-01 → 2026-08-30 30
ECMWF AIFS Single2026-08-01 → 2026-08-30 30

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
Aurora (GFS init) 2 -2.04 [-2.57, -1.50] yes
Aurora (IFS init) 3 -1.50 [-2.86, 0.45] no
FourCastNet v2 (GFS init) 2 +0.64 [0.03, 1.25] yes
FourCastNet v2 (IFS init) 3 +0.59 [-1.73, 1.74] no
NCEP GFS 30 -0.16 [-0.89, 0.30] no
GraphCast (GFS init) 2 -0.54 [-0.68, -0.41] yes
GraphCast (IFS init) 28 -0.10 [-0.31, 0.11] no
ECMWF IFS HRES 25 -1.75 [-2.39, -1.23] yes
Pangu-Weather (GFS init) 2 -1.64 [-2.34, -0.94] yes
Pangu-Weather (IFS init) 3 -0.82 [-1.22, -0.47] yes

Cite this page

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

LongCastCheck (2026). Station-level verification of raw weather-model 2 m temperature forecasts: KSFO (San Francisco Intl), model aifs_single, 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/KSFO/model/aifs_single/lead/0/

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

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