Highest temperature in San Francisco on June 30?

Platform comparison

Market context

The real-world event hinges on the peak temperature recorded at San Francisco International Airport on 30 June 2026, measured in degrees Fahrenheit and sourced from Wunderground. With the crowd-implied probability for a specific range sitting at 0%, the market currently treats that outcome as virtually impossible, suggesting traders expect significantly higher temperatures typical of early summer.

Historical patterns frame this low probability sharply. Daily highs in June at KSFO usually climb from 68°F to 71°F, rarely dipping below 61°F or exceeding 80°F[3]. However, the first half of summer 2026 has been unusually cool, with the average maximum reaching only 67.6°F through mid-July, marking the coldest start since 1965[6]. This anomaly explains why a lower range is priced out, as the market anticipates a rebound to standard seasonal norms rather than continued suppression.

A programmatic trader would monitor real-time METAR feeds and Wunderground updates for deviations, querying dependencies like wind speed and humidity that influence thermal readings. Recent forecasts for July 2026 indicate highs ranging from 67°F to 83°F, suggesting a potential spike above current averages[9]. Traders should watch for official National Weather Service announcements regarding heat advisories or shifts in the Westerly breeze, which currently sits at 18 mph and could moderate peak temperatures if it strengthens[2]. Automated bots would likely execute conditional orders based on these live dependencies to capture the rebound.

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

Polymarket-based markets settle through the UMA Optimistic Oracle on Polygon. A proposer submits the outcome, a two-hour challenge window opens, and unchallenged proposals finalise the resolution. Payouts settle automatically in USDC the moment the result is final — no bookmaker, no delay.

Kalshi-based markets settle in USD via the CFTC-regulated clearinghouse. Betfair Exchange settles in GBP/EUR net of commission. Manifold is play-money and does not pay out real funds.

FAQ

Where can I trade this market with the lowest fees?

Polymarket is geo-blocked in the US/UK/EU. The easiest 0%-fee broker into the same order book is Polymarket Bot UK. Kalshi charges up to 7% per trade; Betfair Exchange takes 2-5% commission on net winnings.

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 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 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.