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

San Francisco Intl · ECMWF AIFS Single · lead day 6

KSFO · 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 QC4.86 [4.06, 5.51]2.31-4.64 [-5.41, -3.59]5.48 [4.60, 6.08]8% [0%, 21%]17%25%-0.30+0.362026-08-07 → 2026-08-30
tmax00Zbilinear90d24 1 QC4.86 [3.90, 5.56]2.31-4.64 [-5.49, -3.20]5.48 [4.39, 6.11]8% [0%, 25%]17%25%-0.30+0.362026-08-07 → 2026-08-30
tmax00Zbilinear365d24 1 QC4.86 [3.85, 5.63]2.31-4.64 [-5.43, -3.31]5.48 [4.42, 6.09]8% [0%, 25%]17%25%-0.30+0.362026-08-07 → 2026-08-30
tmax00Zbilinearall24 1 QC4.86 [3.90, 5.60]2.31-4.64 [-5.50, -3.31]5.48 [4.40, 6.10]8% [0%, 24%]17%25%-0.30+0.362026-08-07 → 2026-08-30
tmax00Znearest30d24 1 QC2.65 [1.85, 3.56]2.30-1.08 [-1.98, 0.42]3.30 [2.33, 4.26]21% [0%, 36%]38%62%+0.29+0.362026-08-07 → 2026-08-30
tmax00Znearest90d24 1 QC2.65 [1.78, 3.66]2.30-1.08 [-2.01, 0.90]3.30 [2.21, 4.38]21% [0%, 37%]38%62%+0.29+0.362026-08-07 → 2026-08-30
tmax00Znearest365d24 1 QC2.65 [1.71, 3.69]2.30-1.08 [-2.02, 0.89]3.30 [2.15, 4.40]21% [0%, 39%]38%62%+0.29+0.362026-08-07 → 2026-08-30
tmax00Znearestall24 1 QC2.65 [1.75, 3.64]2.30-1.08 [-2.10, 0.86]3.30 [2.18, 4.39]21% [0%, 38%]38%62%+0.29+0.362026-08-07 → 2026-08-30
tmax12Zbilinear30d24 1 QC4.92 [4.00, 5.76]2.54-4.42 [-5.49, -3.21]5.56 [4.54, 6.34]4% [0%, 12%]17%21%-0.31+0.292026-08-07 → 2026-08-30
tmax12Zbilinear90d24 1 QC4.92 [3.78, 5.78]2.54-4.42 [-5.53, -2.72]5.56 [4.27, 6.29]4% [0%, 12%]17%21%-0.31+0.292026-08-07 → 2026-08-30
tmax12Zbilinear365d24 1 QC4.92 [3.75, 5.81]2.54-4.42 [-5.57, -2.66]5.56 [4.18, 6.30]4% [0%, 13%]17%21%-0.31+0.292026-08-07 → 2026-08-30
tmax12Zbilinearall24 1 QC4.92 [3.86, 5.85]2.54-4.42 [-5.61, -2.84]5.56 [4.31, 6.36]4% [0%, 12%]17%21%-0.31+0.292026-08-07 → 2026-08-30
tmax12Znearest30d24 1 QC2.98 [2.19, 3.90]2.75-0.69 [-1.81, 0.80]3.76 [2.83, 4.61]12% [4%, 21%]42%67%+0.21+0.232026-08-07 → 2026-08-30
tmax12Znearest90d24 1 QC2.98 [2.15, 4.05]2.75-0.69 [-1.89, 1.31]3.76 [2.71, 4.70]12% [0%, 21%]42%67%+0.21+0.232026-08-07 → 2026-08-30
tmax12Znearest365d24 1 QC2.98 [2.10, 4.10]2.75-0.69 [-1.91, 1.34]3.76 [2.61, 4.75]12% [0%, 21%]42%67%+0.21+0.232026-08-07 → 2026-08-30
tmax12Znearestall24 1 QC2.98 [2.17, 4.10]2.75-0.69 [-1.91, 1.17]3.76 [2.68, 4.72]12% [0%, 20%]42%67%+0.21+0.232026-08-07 → 2026-08-30
tmin00Zbilinear30d24 1 QC1.55 [1.08, 2.13]1.32-0.57 [-1.38, 0.42]1.80 [1.25, 2.40]25% [8%, 46%]75%96%-0.62-0.352026-08-07 → 2026-08-30
tmin00Zbilinear90d24 1 QC1.55 [1.00, 2.23]1.32-0.57 [-1.47, 0.48]1.80 [1.15, 2.45]25% [6%, 50%]75%96%-0.62-0.352026-08-07 → 2026-08-30
tmin00Zbilinear365d24 1 QC1.55 [0.96, 2.28]1.32-0.57 [-1.50, 0.65]1.80 [1.13, 2.52]25% [7%, 50%]75%96%-0.62-0.352026-08-07 → 2026-08-30
tmin00Zbilinearall24 1 QC1.55 [0.98, 2.25]1.32-0.57 [-1.48, 0.47]1.80 [1.16, 2.51]25% [6%, 50%]75%96%-0.62-0.352026-08-07 → 2026-08-30
tmin00Znearest30d24 1 QC1.67 [1.07, 2.51]1.64-0.12 [-1.18, 1.01]2.08 [1.22, 3.01]29% [11%, 53%]75%88%-0.74-0.682026-08-07 → 2026-08-30
tmin00Znearest90d24 1 QC1.67 [0.95, 2.64]1.64-0.12 [-1.27, 1.18]2.08 [1.10, 3.07]29% [9%, 60%]75%88%-0.74-0.682026-08-07 → 2026-08-30
tmin00Znearest365d24 1 QC1.67 [0.96, 2.73]1.64-0.12 [-1.35, 1.19]2.08 [1.11, 3.19]29% [7%, 60%]75%88%-0.74-0.682026-08-07 → 2026-08-30
tmin00Znearestall24 1 QC1.67 [0.97, 2.68]1.64-0.12 [-1.36, 1.12]2.08 [1.13, 3.11]29% [8%, 58%]75%88%-0.74-0.682026-08-07 → 2026-08-30
tmin12Zbilinear30d24 1 QC1.41 [1.10, 1.69]1.01-0.99 [-1.55, -0.29]1.71 [1.37, 2.01]33% [14%, 53%]75%96%-0.47-0.032026-08-07 → 2026-08-30
tmin12Zbilinear90d24 1 QC1.41 [1.07, 1.75]1.01-0.99 [-1.58, -0.08]1.71 [1.31, 2.04]33% [12%, 55%]75%96%-0.47-0.032026-08-07 → 2026-08-30
tmin12Zbilinear365d24 1 QC1.41 [1.10, 1.74]1.01-0.99 [-1.60, -0.11]1.71 [1.33, 2.04]33% [12%, 55%]75%96%-0.47-0.032026-08-07 → 2026-08-30
tmin12Zbilinearall24 1 QC1.41 [1.07, 1.74]1.01-0.99 [-1.62, -0.22]1.71 [1.32, 2.04]33% [12%, 56%]75%96%-0.47-0.032026-08-07 → 2026-08-30
tmin12Znearest30d24 1 QC1.36 [0.93, 1.82]1.20-0.61 [-1.29, 0.22]1.74 [1.21, 2.31]50% [30%, 68%]75%96%-0.42-0.232026-08-07 → 2026-08-30
tmin12Znearest90d24 1 QC1.36 [0.76, 1.89]1.20-0.61 [-1.32, 0.30]1.74 [1.00, 2.42]50% [32%, 75%]75%96%-0.42-0.232026-08-07 → 2026-08-30
tmin12Znearest365d24 1 QC1.36 [0.80, 1.89]1.20-0.61 [-1.36, 0.28]1.74 [1.05, 2.37]50% [29%, 70%]75%96%-0.42-0.232026-08-07 → 2026-08-30
tmin12Znearestall24 1 QC1.36 [0.79, 1.95]1.20-0.61 [-1.39, 0.24]1.74 [1.04, 2.40]50% [29%, 72%]75%96%-0.42-0.232026-08-07 → 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 KSFO, lead day 6, 00Z bilinear tmax+10+50-5-102026-08-07: -1.9 °F2026-08-08: +2.67 °F2026-08-09: -5.49 °F2026-08-10: -6.79 °F2026-08-11: -8.4 °F2026-08-12: -8.08 °F2026-08-13: -4 °F2026-08-14: -4.95 °F2026-08-15: -4.16 °F2026-08-16: -5.2 °F2026-08-17: -7.75 °F2026-08-18: -3.4 °F2026-08-19: -2 °F2026-08-20: -4.85 °F2026-08-21: -3.1 °F2026-08-22: -2.66 °F2026-08-23: -7.7 °F2026-08-24: -6.97 °F2026-08-25: -0.06 °F2026-08-26: -9.82 °F2026-08-27: -6.31 °F2026-08-28: -0.04 °F2026-08-29: -5.03 °F2026-08-30: -5.28 °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
2026-08-30-5.28
2026-08-29-5.03
2026-08-28-0.04
2026-08-27-6.31
2026-08-26-9.82
2026-08-25-0.06
2026-08-24-6.97
2026-08-23-7.70
2026-08-22-2.66
2026-08-21-3.10
2026-08-20-4.85
2026-08-19-2.00
2026-08-18-3.40
2026-08-17-7.75
2026-08-16-5.20
2026-08-15-4.16
2026-08-14-4.95
2026-08-13-4.00
2026-08-12-8.08
2026-08-11-8.40
2026-08-10-6.79
2026-08-09-5.49
2026-08-08+2.67
2026-08-07-1.90

Error distribution

Distribution of the signed daily error in °F for ECMWF AIFS Single at KSFO, lead day 6-10 to -9 °F: 1 day-9 to -8 °F: 2 days-8 to -7 °F: 2 days-7 to -6 °F: 3 days-6 to -5 °F: 4 days-5 to -4 °F: 4 days-4 to -3 °F: 2 days-3 to -2 °F: 1 day-2 to -1 °F: 2 days-1 to 0 °F: 2 days0 to 1 °F: 0 days1 to 2 °F: 0 days2 to 3 °F: 1 day3 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| 4.99 · P90 |e| 7.98 °F-100+10 °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
-10.00-9.001
-9.00-8.002
-8.00-7.002
-7.00-6.003
-6.00-5.004
-5.00-4.004
-4.00-3.002
-3.00-2.001
-2.00-1.002
-1.00+0.002
+0.00+1.000
+1.00+2.000
+2.00+3.001
+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
2026-08244.86 -4.64

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 +0.21 [-0.84, 1.06] no
GraphCast (IFS init) 24 -0.74 [-1.10, -0.14] yes
ECMWF IFS HRES 19 -1.50 [-2.68, 0.53] no
Persistence (baseline) 24 +1.11 [-1.54, 2.40] no

Cite this page

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

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