Highest temperature in San Francisco on June 30?

Platform comparison

Market context

San Francisco rarely experiences extreme heat in June, with long-term averages capping daytime highs near 26°C (79°F) and overnight lows settling around 15°C (59°F)[1]. The current crowd-implied probability of 0% for a "YES" outcome on any high-temperature range reflects this climatic reality, as the city typically sees no days with significant rain or heat spikes during this month[1]. Historical data shows the warmest June day usually occurs around 22 June, averaging just 22.6°C (72.7°F), far below thresholds that would trigger high-temperature contracts[3]. Even recent anomalies, such as the record 90°F hit on 20 March 2026, remain seasonal outliers rather than indicators of June trends[6].

Traders should monitor the National Weather Service’s daily forecasts for the San Francisco Bay Area, particularly any unexpected shifts in marine layer strength or inland heat advection[5]. While the fourth heat wave of 2026 has been discussed on social platforms, current data suggests temperatures above 75°F remain infrequent between February and June[8]. The settlement relies on Wunderground’s official record for the San Francisco International Airport Station, so any discrepancies in sensor readings or data gaps could alter outcomes[7]. With USDC trading on Polygon via conditional tokens, liquidity remains thin for high-temperature ranges, reinforcing the market’s conservative pricing[7]. No major announcements are scheduled to disrupt June weather patterns, keeping the 0% probability well-supported by empirical evidence.

Sources: 1 · 2 · 3 · 4 · 5

Methodology

This page reviews Highest temperature in San Francisco on June 30? across five venues. The live probability is the Polymarket mid-price, sourced directly from the on-chain Polygon order book; the comparison columns benchmark each venue on fee structure, KYC, settlement currency and payment rails. Every CTA routes to PolyGram, which mirrors the Polymarket order book at 0% fees.

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

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