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

San Francisco Intl · ECMWF AIFS Single · lead day 1

KSFO · aifs_single · lead 1

Target day = initialization date + 1 day. 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
tmax00Zbilinear30d29 1 QC4.65 [3.69, 5.72]2.66-4.42 [-5.60, -3.46]5.44 [4.43, 6.41]10% [0%, 21%]28%31%-0.51+0.132026-08-02 → 2026-08-30
tmax00Zbilinear90d29 1 QC4.65 [3.64, 5.97]2.66-4.42 [-5.86, -3.31]5.44 [4.33, 6.57]10% [0%, 21%]28%31%-0.51+0.132026-08-02 → 2026-08-30
tmax00Zbilinear365d29 1 QC4.65 [3.62, 5.99]2.66-4.42 [-5.83, -3.32]5.44 [4.26, 6.66]10% [0%, 22%]28%31%-0.51+0.132026-08-02 → 2026-08-30
tmax00Zbilinearall29 1 QC4.65 [3.65, 6.18]2.66-4.42 [-6.04, -3.38]5.44 [4.32, 6.74]10% [0%, 22%]28%31%-0.51+0.132026-08-02 → 2026-08-30
tmax00Znearest30d29 1 QC2.87 [2.09, 3.73]2.74-0.76 [-2.15, 0.50]3.48 [2.58, 4.30]28% [14%, 41%]41%52%+0.07+0.102026-08-02 → 2026-08-30
tmax00Znearest90d29 1 QC2.87 [2.04, 3.79]2.74-0.76 [-2.27, 0.52]3.48 [2.56, 4.35]28% [11%, 42%]41%52%+0.07+0.102026-08-02 → 2026-08-30
tmax00Znearest365d29 1 QC2.87 [1.95, 3.93]2.74-0.76 [-2.45, 0.57]3.48 [2.46, 4.45]28% [10%, 43%]41%52%+0.07+0.102026-08-02 → 2026-08-30
tmax00Znearestall29 1 QC2.87 [2.03, 3.87]2.74-0.76 [-2.45, 0.65]3.48 [2.55, 4.39]28% [11%, 43%]41%52%+0.07+0.102026-08-02 → 2026-08-30
tmax12Zbilinear30d29 1 QC4.64 [3.59, 5.78]2.62-4.50 [-5.72, -3.44]5.48 [4.38, 6.48]21% [7%, 34%]28%31%-0.51+0.142026-08-02 → 2026-08-30
tmax12Zbilinear90d29 1 QC4.64 [3.51, 6.01]2.62-4.50 [-5.96, -3.35]5.48 [4.31, 6.70]21% [7%, 34%]28%31%-0.51+0.142026-08-02 → 2026-08-30
tmax12Zbilinear365d29 1 QC4.64 [3.51, 6.05]2.62-4.50 [-6.01, -3.32]5.48 [4.24, 6.76]21% [7%, 36%]28%31%-0.51+0.142026-08-02 → 2026-08-30
tmax12Zbilinearall29 1 QC4.64 [3.55, 6.23]2.62-4.50 [-6.20, -3.37]5.48 [4.28, 6.84]21% [5%, 35%]28%31%-0.51+0.142026-08-02 → 2026-08-30
tmax12Znearest30d29 1 QC2.87 [2.14, 3.66]2.72-0.78 [-2.17, 0.40]3.44 [2.63, 4.22]24% [10%, 39%]41%48%+0.07+0.112026-08-02 → 2026-08-30
tmax12Znearest90d29 1 QC2.87 [2.07, 3.73]2.72-0.78 [-2.30, 0.45]3.44 [2.58, 4.26]24% [8%, 41%]41%48%+0.07+0.112026-08-02 → 2026-08-30
tmax12Znearest365d29 1 QC2.87 [2.00, 3.85]2.72-0.78 [-2.48, 0.48]3.44 [2.54, 4.35]24% [7%, 42%]41%48%+0.07+0.112026-08-02 → 2026-08-30
tmax12Znearestall29 1 QC2.87 [2.09, 3.80]2.72-0.78 [-2.50, 0.50]3.44 [2.58, 4.29]24% [7%, 42%]41%48%+0.07+0.112026-08-02 → 2026-08-30
tmin00Zbilinear30d29 1 QC0.94 [0.61, 1.31]0.87-0.45 [-0.80, -0.03]1.21 [0.86, 1.51]62% [39%, 83%]90%100%+0.03+0.102026-08-02 → 2026-08-30
tmin00Zbilinear90d29 1 QC0.94 [0.58, 1.36]0.87-0.45 [-0.87, -0.02]1.21 [0.83, 1.54]62% [36%, 85%]90%100%+0.03+0.102026-08-02 → 2026-08-30
tmin00Zbilinear365d29 1 QC0.94 [0.59, 1.38]0.87-0.45 [-0.86, 0.02]1.21 [0.82, 1.57]62% [30%, 85%]90%100%+0.03+0.102026-08-02 → 2026-08-30
tmin00Zbilinearall29 1 QC0.94 [0.55, 1.38]0.87-0.45 [-0.91, -0.01]1.21 [0.79, 1.56]62% [33%, 86%]90%100%+0.03+0.102026-08-02 → 2026-08-30
tmin00Znearest30d29 1 QC1.12 [0.88, 1.42]1.12-0.14 [-0.63, 0.40]1.38 [1.02, 1.70]48% [30%, 63%]90%97%-0.16-0.162026-08-02 → 2026-08-30
tmin00Znearest90d29 1 QC1.12 [0.85, 1.49]1.12-0.14 [-0.68, 0.44]1.38 [0.95, 1.79]48% [29%, 67%]90%97%-0.16-0.162026-08-02 → 2026-08-30
tmin00Znearest365d29 1 QC1.12 [0.85, 1.53]1.12-0.14 [-0.70, 0.44]1.38 [0.94, 1.82]48% [29%, 65%]90%97%-0.16-0.162026-08-02 → 2026-08-30
tmin00Znearestall29 1 QC1.12 [0.85, 1.51]1.12-0.14 [-0.76, 0.43]1.38 [0.96, 1.78]48% [29%, 66%]90%97%-0.16-0.162026-08-02 → 2026-08-30
tmin12Zbilinear30d29 1 QC0.85 [0.51, 1.20]0.79-0.37 [-0.67, -0.04]1.11 [0.78, 1.40]59% [36%, 80%]90%100%+0.12+0.192026-08-02 → 2026-08-30
tmin12Zbilinear90d29 1 QC0.85 [0.48, 1.22]0.79-0.37 [-0.71, -0.04]1.11 [0.73, 1.45]59% [33%, 81%]90%100%+0.12+0.192026-08-02 → 2026-08-30
tmin12Zbilinear365d29 1 QC0.85 [0.51, 1.28]0.79-0.37 [-0.71, 0.00]1.11 [0.73, 1.47]59% [30%, 80%]90%100%+0.12+0.192026-08-02 → 2026-08-30
tmin12Zbilinearall29 1 QC0.85 [0.48, 1.26]0.79-0.37 [-0.75, -0.03]1.11 [0.72, 1.47]59% [32%, 82%]90%100%+0.12+0.192026-08-02 → 2026-08-30
tmin12Znearest30d29 1 QC1.09 [0.89, 1.34]1.09-0.03 [-0.47, 0.48]1.32 [1.00, 1.62]59% [45%, 72%]90%97%-0.13-0.132026-08-02 → 2026-08-30
tmin12Znearest90d29 1 QC1.09 [0.87, 1.42]1.09-0.03 [-0.55, 0.50]1.32 [0.93, 1.69]59% [42%, 75%]90%97%-0.13-0.132026-08-02 → 2026-08-30
tmin12Znearest365d29 1 QC1.09 [0.87, 1.43]1.09-0.03 [-0.55, 0.48]1.32 [0.94, 1.73]59% [40%, 75%]90%97%-0.13-0.132026-08-02 → 2026-08-30
tmin12Znearestall29 1 QC1.09 [0.87, 1.42]1.09-0.03 [-0.58, 0.47]1.32 [0.95, 1.71]59% [40%, 75%]90%97%-0.13-0.132026-08-02 → 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 1, 00Z bilinear tmax+10+50-5-102026-08-02: -8.39 °F2026-08-03: -7.75 °F2026-08-04: -5.72 °F2026-08-05: -4.76 °F2026-08-06: -4.55 °F2026-08-07: -0.44 °F2026-08-08: +1.54 °F2026-08-09: -0.82 °F2026-08-10: -5.84 °F2026-08-11: -9.53 °F2026-08-12: -9.6 °F2026-08-13: -8.37 °F2026-08-14: -6.73 °F2026-08-15: -4.18 °F2026-08-16: -2.7 °F2026-08-17: -6.68 °F2026-08-18: -1.6 °F2026-08-19: -1.04 °F2026-08-20: -3.57 °F2026-08-21: -3.05 °F2026-08-22: -1.29 °F2026-08-23: -8.3 °F2026-08-24: -6.94 °F2026-08-25: +0.55 °F2026-08-26: -4.81 °F2026-08-27: -3.52 °F2026-08-28: +1.25 °F2026-08-29: -5.94 °F2026-08-30: -5.32 °F2026-08-022026-08-30°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 (29 days, newest first) · download CSV
Climatological dayError °F
2026-08-30-5.32
2026-08-29-5.94
2026-08-28+1.25
2026-08-27-3.52
2026-08-26-4.81
2026-08-25+0.55
2026-08-24-6.94
2026-08-23-8.30
2026-08-22-1.29
2026-08-21-3.05
2026-08-20-3.57
2026-08-19-1.04
2026-08-18-1.60
2026-08-17-6.68
2026-08-16-2.70
2026-08-15-4.18
2026-08-14-6.73
2026-08-13-8.37
2026-08-12-9.60
2026-08-11-9.53
2026-08-10-5.84
2026-08-09-0.82
2026-08-08+1.54
2026-08-07-0.44
2026-08-06-4.55
2026-08-05-4.76
2026-08-04-5.72
2026-08-03-7.75
2026-08-02-8.39

Error distribution

Distribution of the signed daily error in °F for ECMWF AIFS Single at KSFO, lead day 1-10 to -9 °F: 2 days-9 to -8 °F: 3 days-8 to -7 °F: 1 day-7 to -6 °F: 3 days-6 to -5 °F: 4 days-5 to -4 °F: 4 days-4 to -3 °F: 3 days-3 to -2 °F: 1 day-2 to -1 °F: 3 days-1 to 0 °F: 2 days0 to 1 °F: 1 day1 to 2 °F: 2 days2 to 3 °F: 0 days3 to 4 °F: 0 days4 to 5 °F: 0 days5 to 6 °F: 0 days6 to 7 °F: 0 days7 to 8 °F: 0 days8 to 9 °F: 0 days9 to 10 °F: 0 daysdashed: P50 |e| 4.76 · P90 |e| 8.37 °F-100+10 °Fn = 29 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
-10.00-9.002
-9.00-8.003
-8.00-7.001
-7.00-6.003
-6.00-5.004
-5.00-4.004
-4.00-3.003
-3.00-2.001
-2.00-1.003
-1.00+0.002
+0.00+1.001
+1.00+2.002
+2.00+3.000
+3.00+4.000
+4.00+5.000
+5.00+6.000
+6.00+7.000
+7.00+8.000
+8.00+9.000
+9.00+10.000

Month by month

00Z bilinear daily maximum, newest first.

Monthn MAE °FBias °F
2026-08294.65 -4.42

Availability

ModelScored period DaysCoverage
ECMWF AIFS Single2026-08-02 → 2026-08-30 29
ECMWF AIFS Single2026-08-02 → 2026-08-30 29
ECMWF AIFS Single2026-08-02 → 2026-08-30 29
ECMWF AIFS Single2026-08-02 → 2026-08-30 29

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) 1 -1.32 [-1.32, -1.32] yes
Aurora (IFS init) 2 -2.69 [-2.98, -2.40] yes
FourCastNet v2 (GFS init) 1 +3.91 [3.91, 3.91] yes
FourCastNet v2 (IFS init) 2 +3.18 [3.00, 3.37] yes
NCEP GFS 29 -0.10 [-0.53, 0.23] no
GraphCast (GFS init) 1 +0.68 [0.68, 0.68] yes
GraphCast (IFS init) 27 -0.25 [-0.45, 0.00] no
ECMWF IFS HRES 22 -1.74 [-2.49, -0.84] yes
Pangu-Weather (GFS init) 1 -1.32 [-1.32, -1.32] yes
Pangu-Weather (IFS init) 2 -1.07 [-1.49, -0.65] yes
Persistence (baseline) 29 +1.58 [-0.35, 3.45] no

Cite this page

ShortCastCheck, KSFO aifs_single lead 1, methodology v0.2, accessed 2026-08-31, https://castcheck.zifanzhang.com/station/KSFO/model/aifs_single/lead/1/

LongCastCheck (2026). Station-level verification of raw weather-model 2 m temperature forecasts: KSFO (San Francisco Intl), model aifs_single, lead day 1. 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/1/

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

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