Highest temperature in San Francisco on July 12?

Platform comparison

Market context

San Francisco’s highest temperature on 12 July 2026 will be measured at the San Francisco International Airport Station, with resolution based on Wunderground’s daily record for KSFO. Today, Polymarket prices this contract with the crowd assigning 0% probability to any “YES” outcome, yet the frontrunner range is 72–73°F at 39% chance, followed by 70–71°F at 25% [1]. This divergence suggests traders are betting on a specific band rather than a binary yes/no, reflecting the market’s conditional-token structure on Polygon where USDC settles outcomes automatically once the temperature threshold is confirmed.

Historically, July highs in San Francisco average around 70°F, rarely dipping below 64°F or exceeding 79°F, with the all-time record reaching 106°F [2][5]. Notably, on 12 July 2021, the city hit a record-low maximum of 57°F, tying 1912, 1901, and 1899, while just last week SF recorded 73°F—its third-hottest week in over 150 years [6][8]. These extremes frame the current 0% YES probability as a mispricing if traders expect a return to typical July warmth rather than another anomalous cool day.

Traders should monitor the National Weather Service Bay Area forecasts and Wunderground’s hourly updates for KSFO, as heat-wave announcements or marine-layer shifts could rapidly alter the temperature range [3]. The settlement window closes at 12:00 UTC on 12 July 2026, so any pre-12:00 UTC temperature spike will lock the outcome. Recent news highlights SF’s volatility, with a 73°F record breaking a 125-year-old January benchmark, underscoring how quickly conditions can change [6].

Sources: 1 · 2 · 3 · 4 · 5

Methodology

Methodologically we separate two layers: the live probability (Polymarket mid-price) and the platform attributes (fee, KYC, settlement currency, payment rails). That keeps the comparison honest — a single canonical probability across the row, with the venue-by-venue trade-offs spelt out in the columns next to it.

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

Is this market available outside the US?

Polymarket itself is geo-blocked in the US/UK/EU. Always check the legal status of prediction markets in your jurisdiction before trading.

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 PolyGram trigger KYC only above $1,500 of lifetime trading volume; under that you trade pseudonymously with a single wallet address.