Highest temperature in San Francisco on July 12?

Platform comparison

Market context

San Francisco International Airport is set to record its peak temperature for 12 July 2026, with the market currently pricing a 0% chance of any outcome outside the implied consensus. While the crowd dismisses extreme heat, historical climatology suggests daily highs in July typically hover around 70°F, rarely exceeding 79°F or dropping below 64°F[2]. The closely priced 72–73°F outcome reflects this standard range where fog often lingers into midday, yet the market’s frontrunner for this specific band sits at 30% probability, indicating a crowded field rather than a definitive signal[1]. A similar contract for 6 July saw traders favour the 66–67°F band at 33.5%, a plurality leader that still diluted confidence across ten competing outcomes[3].

Traders should monitor real-time updates from Wunderground, the designated resolution source for the KSFO station, as fog patterns and marine layer breaks can shift peak temperatures within hours[1]. Recent data shows the highest temperature in the last fifteen days was 72.6°F on 29 June, while the lowest was 54.3°F on 11 July, suggesting volatility is possible even in summer[7]. Although all-time records for the Bay Area reached 106°F in September 2017, July conditions remain temperate, with 12 July 2021 notably tying a record low maximum of 57°F[4][10]. The divergence between the 0% crowd-implied probability for extreme outliers and the 30% probability for the 72–73°F range highlights the market’s reliance on typical climatology over speculative heatwaves.

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.

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 Best Prediction Markets 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.