Highest temperature in San Francisco on July 12?

Platform comparison

Market context

The event in question is the peak Fahrenheit reading at San Francisco International Airport on 12 July 2026, a date historically prone to moderate coastal cooling rather than extreme heat. Current crowd-implied probability sits at 0% for any outcome, suggesting the market expects a resolution outside the listed ranges or a data anomaly, though this contradicts typical July climatology where highs usually fall between 67°F and 79°F[2]. Historical data from July 2021 shows the airport recorded a record low maximum of 67°F on 12 July, while recent 2026 data indicates the first half of summer has been the coldest since 1965 with an average max of just 67.6°F[5][10]. This persistent cooling trend frames the 0% probability as a potential mispricing, as even the coldest recent summers still produce temperatures within standard forecast bands.

A programmatic trader should monitor the Wunderground daily history feed for KSFO, which serves as the definitive resolution source, and cross-reference it with National Weather Service time-series data for real-time validation[8]. Key catalysts include the 10-day forecast indicating a high of 75°F for 12 July, which aligns with the upper bound of the expected range and suggests the 0% probability is likely an error in the market’s range definitions rather than a genuine expectation of no temperature recording[7]. Traders building bots should script checks for the specific gear-icon temperature unit toggle on Wunderground to ensure Fahrenheit data is parsed correctly, as a Celsius misread would invalidate any automated position. The dependency on a single external data source creates a clear arbitrage window if the live NWS feed diverges significantly from the Wunderground archive before settlement.

Sources: 1 · 2 · 3 · 4 · 5

Methodology

We track Highest temperature in San Francisco on July 12? across the five venues with material prediction-market liquidity. The probability shown is the live Polymarket mid; the comparison rows summarise how each venue treats the underlying contract — fees, KYC thresholds, settlement currency, deposit options. The highlighted row marks the cheapest route into Polymarket's order book.

Resolution & payout

Settlement runs on-chain. Polymarket's contract logic separates YES and NO shares as conditional tokens; at resolution the winning share lifts to $1.00 and the losing one to $0. The outcome input comes from the UMA Optimistic Oracle, which secures against bad resolution with a bond + dispute window.

Once finalised, the smart contract pays USDC to the holders' wallets within minutes — no withdrawal fees beyond Polygon network gas. Kalshi settles in USD via CFTC clearance, Betfair in account currency net of commission, Manifold in play-money mana with no cash-out.

FAQ

How does resolution work?

Through the UMA Optimistic Oracle on Polygon: a proposer submits the outcome, a two-hour challenge window opens, and USDC payouts settle automatically once the result is final.

What's the difference between YES and NO shares?

A YES share pays $1.00 if the event happens, $0 otherwise. A NO share pays $1.00 if the event doesn't happen. The market price between 0¢ and 100¢ is the implied probability.

What does Polymarket cost to trade?

Polymarket itself charges 0% — the only cost is the Polygon network fee, typically under $0.01 per transaction. Off-chain venues like Kalshi or Betfair charge 2-7% commission.

Do I need to KYC for this market?

On Polymarket directly, no — it's wallet-based. Intermediary brokers like Polymarket Bot UK trigger KYC only above $1,500 of lifetime trading volume; under that you trade pseudonymously with a single wallet address.

How reliable are the quoted odds?

The YES/NO percentages are the live mid-prices of the Polymarket order book. On deep markets they move every few seconds; on thinner ones you'll see short plateaus.