Highest temperature in Sao Paulo on June 30?

Platform comparison

Market context

On 30 June 2026, the real-world event hinges on the peak temperature recorded at São Paulo–Guarulhos International Airport, where June historically delivers mildly cool, breezy conditions with average highs of just 23°C (73°F) and lows of 13°C (55°F)[1]. The crowd-implied probability of 0% for a "YES" outcome (likely meaning an extreme high) aligns with consensus that June is São Paulo’s coldest period, with July averaging even lower lows of 56°F (13°C)[3]. While the city has recorded scorching December peaks of 35.9°C (96.6°F) and November extremes of 38.5°C (101.3°F), these are winter anomalies in the Southern Hemisphere, making a June spike of similar magnitude a statistical outlier rather than a value spot[4][6].

Traders should watch for any sudden shifts in regional wind patterns or unseasonal heatwave announcements, as São Paulo’s humidity (averaging 82%) can trap warmth if breezes stall[1]. Recent data shows the highest temperature in the past 15 days was only 26.0°C (78.8°F) on 22 June 2026, reinforcing the underdog status of extreme heat forecasts[2]. The consensus remains firmly on the underdog side, but contrarian value might sit in betting against the 0% probability if a rare, unforecasted subtropical ridge moves in, though dependencies on Wunderground’s daily logs mean verification will be strict[8]. No major climate announcements are scheduled, so the market relies on raw observational data rather than predictive models.

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

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 Who Will Win. 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.

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