Highest temperature in San Francisco on June 30?

Platform comparison

Market context

The highest temperature recorded at San Francisco International Airport on 30 June 2026 will determine the outcome of this prediction market, with the settlement window closing at 12:00 UTC on that day. Today, Polymarket prices the YES contract for any temperature range above the current implied threshold at 0%, reflecting a crowd consensus that extreme heat is virtually impossible for this date and location.

Historically, June in San Francisco rarely sees temperatures exceeding 80°F, with daily highs typically climbing from 68°F to 71°F and rarely 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 temperature of just 67.6°F through 15 July[6]. Such persistent cool patterns frame the current 0% probability as a rational assessment rather than an outlier, given the region’s maritime climate and recent weather trends.

Traders should monitor the National Weather Service’s daily climatological reports for any sudden shifts in forecasted highs, as well as real-time METAR data from KSFO for immediate temperature spikes[3][4]. While July forecasts suggest highs could reach 83°F, the current cool trend and fresh westerly winds observed today (18 mph) make a breakthrough unlikely[1][5]. No major announcements are expected to alter this trajectory, and the market’s on-chain mechanics—settling in USDC on Polygon via conditional tokens—will resolve cleanly once Wunderground publishes the official daily maximum[1].

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

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

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.

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 Polymarket Legit? trigger KYC only above $1,500 of lifetime trading volume; under that you trade pseudonymously with a single wallet address.