Highest temperature in San Francisco on June 30?

Platform comparison

Market context

The real-world event at hand is the highest temperature recorded today at San Francisco International Airport, which currently sits at 72°F with a forecast high of 67°F under sunny skies and a fresh westerly breeze[1][6]. This specific day, 30 June 2026, falls within a historically cool June where daily highs typically climb from 68°F to 71°F, rarely exceeding 80°F[2]. The current crowd-implied probability of 0% for a higher range aligns with the fact that this year marks the coldest first half of summer at SFO since 1965, with an average maximum of just 67.6°F through mid-July[7]. Such a baseline suggests that any temperature significantly above the 66–69°F range is statistically improbable given the prevailing maritime influence and lack of heatwaves[4].

A power-user approaching this market programmatically would monitor real-time Wunderground feeds for the KSFO station, setting conditional orders to trigger if temperatures breach 75°F before the settlement window closes[8]. The primary catalyst to watch is the National Weather Service climatological report, which confirms today’s maximum record of 73°F against a normal of 73°F, indicating no anomalous heat spike[9]. Traders should also track the weekly forecast for July, which projects highs between 67°F and 83°F, but the immediate dependency remains the current westerly wind flow at 18 mph, which suppresses rapid temperature rises[1][5]. No recent news announcements suggest a sudden shift in weather patterns, reinforcing the 0% probability for higher ranges in the absence of a heat event[7].

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

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.

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 Polymarket Review 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.