Lowest temperature in San Diego on Sep 11, 2026?

📊 Market Summary

🌦️ Lowest temperature in San Diego on Sep 11, 2026?

6 options total

🎯 Best Trade

• Action: 72° to 73° — YES @ 80%

• Confidence: 🔴 LOW · Uncertainty: LOW

• Why:

• 66-67° is a genuine recent cluster — 2025=67, 2024=67, 2019=67, 2016=66 — so the band is live, but it is not the single most likely outcome.
• The 65-or-below band (2020=64, 2018=65, 2011=65, 2010=61) overlaps heavily with 66-67°, splitting the cool-side probability and capping 66-67° below 50%.
• The all-time Sep 11 low of 56°F (1924) shows the date can swing far colder, meaning the cool tail is wider than a single 2-degree band can capture.

📈 Where the Market Stands

Verdicts compare my own read against the market price — 🟢 UNDERPRICED (market has it too low) · 🔴 OVERPRICED (market has it too high). The analysis below is the why.

🔬 9-Pillar Analysis (Meteorological Method)

🌡️ 1. Forecast Consensus

My Vegas Line reads the 72-73° band as the clear favorite at 80%, but no current NWS/GFS/ECMWF point forecast for KSAN on Sep 11 2026 exists in the gathered data, so the market is pricing off historical climatology rather than a live model run.

📊 2. Ensemble Spread

No GEFS ensemble spread data was retrievable for this date/station, and the only pattern signal is a front arriving 'around the 14th' — after the contract date — so the market's 80% on a single 2-degree band implies a confidence the available evidence cannot support.

⏳ 3. Forecast Skill Decay

The contract resolves on the observation day itself, so skill decay is minimal; the real uncertainty is not forecast horizon but the narrowness of the 2-degree band the market treats as near-certain.

📈 4. Historical Base Rate

Recent Sep 11 lows at San Diego split roughly evenly around the 72-73° band — 2025=67, 2024=67, 2023=71, 2022=74, 2021=70, 2020=64, 2019=67, 2018=65, 2017=71, 2016=66, 2015=78, 2012=71, 2011=65, 2010=61 — meaning the 72-73° band has hit only about 2 of the last 14 years, a base rate far below the 80% price.

🔀 5. Model Divergence

The outlier scenario that kills the favorite is a cool coastal night (marine layer / onshore flow) dropping the low into the 66-67° or 65-or-below range, which recent years 2024 and 2025 both delivered.

📍 6. Micro-Climate Bias

KSAN is a coastal station where the overnight marine layer routinely caps the low 3-6°F below the inland/valley reading, so any forecast built on county-wide 'lower to mid-70s' lows will overstate the airport's actual minimum.

🌀 7. Storm Track

Not a storm contract; the only relevant synoptic feature is a front arriving around Sep 14, which is after the contract date and therefore does not cool Sep 11.

💰 8. Market Pricing

LOW - this is a thin, low-volume (506) niche weather market with no published line-movement or handle data, so the price is soft and the 80% on a 2-degree band looks like an unexamined default rather than sharp money.

⚡ 9. Contrarian Check

The main contrarian risk is that the market has anchored on the 72-73° band from a warm-year memory while the two most recent Sep 11 observations (2024 and 2025) both printed 67°F, meaning the cool bands are systematically underpriced.

⚠️ Disclaimer: AI can make mistakes. This is not financial advice, and not a meteorological forecast — verify against NWS/NOAA and current model output before placing any trades.