Highest temperature in San Francisco on July 13?

Platform comparison

Market context

The market hinges on whether San Francisco International Airport records a peak temperature exceeding 79°F on 13 July 2026, a threshold the crowd prices at a mere 7% probability. Historical data for mid-July in the city shows daily highs typically cluster around 70°F, rarely breaching 79°F, with the all-time record for the airport sitting at 87°F set during a 2013 heatwave [1][2]. While the Bay Area has seen triple-digit temperatures in inland locations like Healdsburg, the coastal airport’s marine layer usually suppresses extremes, making a breach of the 79°F cap an outlier event rather than a seasonal norm [3].

Traders should monitor the National Weather Service’s hourly KSFO observations and the real-time Wunderground history feed as the settlement window closes at 12:00 UTC on 13 July [8][9]. A significant catalyst would be the breakdown of the marine layer due to an approaching high-pressure ridge, a pattern that previously drove the 87°F record [2]. In the crypto context, this weather contract settles in USDC on-chain, offering a non-correlated hedge against BTC or ETH volatility if macro funding rates tighten; whale flows into such binary weather events often spike when spot exchanges show low liquidity, creating arbitrage opportunities between prediction markets and traditional weather derivatives.

Sources: 1 · 2 · 3 · 4 · 5

Methodology

Methodologically this overview focuses on on-chain pricing: Polymarket's live mid comes from the Polygon conditional-token order book and settles automatically in USDC. The other three venues — Kalshi, Betfair, Manifold — sit alongside as off-chain reference points so you can see how the contract translates across regulatory and settlement regimes.

Resolution & payout

Settlement is on-chain via UMA Optimistic Oracle. A proposer posts the outcome with a bond, a two-hour dispute window opens, then the smart contract lifts winning conditional tokens to 1 USDC and sends payments to holders' wallets automatically. No withdrawal fees beyond Polygon gas.

Off-chain venues (Kalshi, Betfair, Smarkets) settle in local fiat through bank-side clearing — faster than SWIFT, slower than on-chain. Manifold pays no real cash.

FAQ

Why USDC and not ETH or USDT?

USDC is the Polygon standard — audited reserves (Circle, monthly attestation), deepest order book, low gas costs. ETH volatility would distort probability quotes; USDT has thinner Polygon liquidity than USDC.

What does a transaction cost on Polygon?

Polygon gas is typically under $0.01 per transaction. A full trade cycle (Approve + Order + Fill) totals around $0.03 — compared to $5-50 on Ethereum mainnet.

Can I use Bitcoin directly?

No, Polymarket operates exclusively in USDC on Polygon. You can bridge BTC to USDC via an exchange or bridge service and deposit on Polygon — typically 10-30 minutes processing time.

How does UMA secure the resolution?

The UMA Optimistic Oracle uses a bond system: a proposer posts a bond, a two-hour challenge window opens. On dispute the losing side forfeits the bond — financial incentive for honest resolution.

Are crypto prediction markets taxable in the US?

In the US, prediction market gains are typically treated as ordinary income or short-term capital gains depending on holding period. Consult a tax professional for your specific situation — we cannot provide tax advice.