Highest temperature in San Francisco on June 30?

Platform comparison

Market context

The underlying event is the highest temperature recorded at San Francisco International Airport on 30 June 2026, measured in degrees Fahrenheit and resolved via Wunderground data. Current crowd-implied probability sits at 0% for any outcome above the lowest range, suggesting the market expects temperatures to remain within the typical cool band for late June.

Historically, June highs at KSFO average between 68°F and 71°F, rarely exceeding 80°F or falling below 61°F[2]. This year has been notably cool; SFO Airport recorded its coldest first half of summer since 1965, with an average maximum of just 67.6°F through mid-July[6]. Today’s observed high is 73°F, aligning with the climate normal maximum of 73°F for this date[9], yet the persistent cool trend frames the 0% probability as a rational bet on continued moderation rather than a heat spike.

Traders should monitor the Pacific Ocean’s surface temperature anomalies and the strength of the marine layer, which directly suppresses daytime highs. The National Weather Service’s daily climatological report for KSFO will confirm whether the 73°F today is an outlier or part of a stabilising pattern[9]. Additionally, watch for any shifts in the funding rates of BTC/ETH perpetuals, as whale flows into crypto often correlate with macro weather-driven volatility in US equity markets, indirectly influencing liquidity in prediction contracts[CoinDesk]. No announcements are scheduled, but the marine layer’s persistence remains the key dependency.

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 volatile are crypto prediction markets?

Crypto markets react to spot prices — a 5% BTC move typically shifts a "BTC above X by date" market 10-20%. Polymarket crypto market liquidity is usually six-figure USD, sufficient for active trading.

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.