Highest temperature in San Francisco on June 30?

Platform comparison

Market context

On 30 June 2026, the San Francisco International Airport Station will record its peak temperature for the day, a real-world event that determines the outcome of this prediction market. The crowd-implied probability for a YES result sits at 0%, reflecting a consensus that the temperature will fall outside the favoured range. Historically, late June in San Francisco is mild, with the highest daily average high reaching just 70°F on 29 June, and recent data from mid-to-late June 2026 showing a peak of only 72.6°F[2][3]. While record highs have breached 100°F in extreme events like the 2000 and 2017 heatwaves, such outliers are rare and typically associated with specific atmospheric conditions not evident in the current seasonal pattern[5].

Traders should monitor the National Weather Service’s daily observations for KSFO and any sudden shifts in marine layer coverage, which can suppress temperatures, or rare inland heat domes that could spike them[1]. A contrarian angle might exist if a forecasted heat dome, similar to those that drove Bay Area records in 1982 and 2023, materialises unexpectedly, pushing temperatures toward the 90°F threshold[9]. However, without a confirmed forecast of such an event, the value spot likely remains on the underdog side, as the consensus correctly identifies the low likelihood of a record-breaking day in typical June conditions. The settlement window closes at 12:00 UTC on 30 June 2026, with Wunderground serving as the definitive resolution source.

Sources: 1 · 2 · 3 · 4 · 5

Methodology

We track Highest temperature in San Francisco on June 30? 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

Where can I trade this market with the lowest fees?

Polymarket is geo-blocked in the US/UK/EU. The easiest 0%-fee broker into the same order book is Who Will Win 2026. Kalshi charges up to 7% per trade; Betfair Exchange takes 2-5% commission on net winnings.

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 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.

How fast are USDC deposits?

Polygon credits deposits after 12 confirmations — usually under 30 seconds. Withdrawals follow the same path and land back in your wallet within minutes.

Do I need to KYC for this market?

On Polymarket directly, no — it's wallet-based. Intermediary brokers like Who Will Win 2026 trigger KYC only above $1,500 of lifetime trading volume; under that you trade pseudonymously with a single wallet address.