Highest temperature in Sao Paulo on June 30?

Platform comparison

Market context

The real-world event is the highest temperature recorded on 30 June 2026 at São Paulo–Guarulhos International Airport, measured in degrees Celsius and sourced from Wunderground. Historical patterns for São Paulo in June show daily highs averaging around 22°C (72°F), rarely dipping below 17°C (63°F) or exceeding 26°C (79°F)[1]. Recent data from mid-June 2026 confirms this trend, with the peak temperature reaching 26.0°C (78.8°F) on 22 June[2]. The current crowd-implied probability of 0% for a “YES” outcome—presumably indicating a temperature above a specific threshold—appears inconsistent with these baselines unless the threshold is set well above 26°C, which is atypical for June.

A power-user evaluating this market programmatically would monitor real-time Wunderground feeds for the SBGR station, cross-referencing with local meteorological bulletins from Brazil’s National Meteorology Institute (INMET). Key catalysts include sudden shifts in cloud cover, wind direction from the Atlantic, or unseasonal heatwaves linked to regional pressure anomalies. While no major weather announcements have been issued for late June 2026 as of today, traders should watch INMET’s daily updates and Wunderground’s hourly logs for deviations from the 22–26°C range[1][2]. Any sustained rise above 27°C would warrant immediate re-evaluation of the implied probability, given that such temperatures are historically rare in São Paulo during June[1][3].

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 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.

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