Highest temperature in San Francisco on August 13?

Platform comparison

Market context

San Francisco's peak temperature on 13 August 2026 will be measured at the airport weather station and recorded in Weather Underground's Daily Observations table, with settlement determined by which temperature band contains that highest reading in Fahrenheit. The current crowd-implied probability of 0% suggests traders are pricing this as an outcome with negligible likelihood, though the specific temperature threshold triggering a YES resolution remains unspecified in available market documentation.

August temperatures in San Francisco rarely exceed 75°F at the airport station, with historical data showing the warmest August days typically peak in the low-to-mid 70s. The all-time August high at SFO stands at 96°F, recorded in 1961, making extreme heat exceptionally rare for the region. This historical pattern explains the depressed probability, as typical summer conditions favour marine layer influence and coastal cooling. Comparable prediction markets on San Francisco summer temperatures have consistently resolved to moderate ranges, with extreme heat outcomes trading at negligible odds.

Traders monitoring this contract should track National Weather Service forecasts issued in early August 2026, particularly any heat advisories or unusual atmospheric patterns that might drive temperatures significantly above seasonal norms. High-pressure systems moving into Northern California during mid-August could alter baseline expectations, though such events remain statistically uncommon. The resolution methodology's reliance on Weather Underground's Daily Observations table rather than summary figures introduces a technical dependency worth confirming before settlement approaches.

Methodology

This page reviews Highest temperature in San Francisco on August 13? across five venues. The live probability is the Polymarket mid-price, sourced directly from the on-chain Polygon order book; the comparison columns benchmark each venue on fee structure, KYC, settlement currency and payment rails. Every CTA routes to Kalshi vs Polymarket, which mirrors the Polymarket order book at 0% fees.

Resolution & payout

At resolution the UMA oracle takes over: a proposer posts the outcome with a bond, any token holder can dispute within two hours. Without dispute the result is accepted and the smart contract distributes USDC instantly.

On Kalshi (CFTC-regulated) resolution runs through their in-house clearing engine in USD. Betfair Exchange settles after match end in the account's local currency. Manifold pays no cash — only its in-platform "mana" currency.

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.

Do I need to KYC for this market?

On Polymarket directly, no — it's wallet-based. Intermediary brokers like Kalshi vs Polymarket 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.