Highest temperature in Sao Paulo on June 30?

Platform comparison

Market context

On 30 June 2026, the highest temperature recorded at São Paulo–Guarulhos International Airport will determine the outcome of this prediction market, with settlement based on Wunderground data. Historically, June in São Paulo is mildly cool and breezy, with average highs of 23°C and lows of 13°C, making extreme heat unlikely during this month[1]. Recent data from the past 15 days shows the highest temperature reached was 26°C on 22 June 2026, while the lowest was 9.4°C on 18 June[2]. Even São Paulo’s hottest recorded day in history occurred in November 2023 at 38.5°C, far outside the typical June range[5]. Given these patterns, the crowd-implied 0% probability for a high-temperature outcome aligns with climatic norms.

Traders approaching this market programmatically should monitor real-time Wunderground feeds for the airport station, setting conditional orders to trigger only if temperatures exceed 30°C. Key catalysts include any sudden shifts in regional wind patterns or humidity spikes, which could elevate temperatures unexpectedly. While no specific weather announcements are currently scheduled for late June, meteorological services in Brazil often issue heat advisories when temperatures approach 35°C, a threshold rarely reached in June[6]. Power-users should also track the gear icon temperature setting on Wunderground to ensure data is in Celsius, avoiding conversion errors. With settlement ending 12:00 UTC on 30 June, automated bots must execute final checks before this deadline to capture the day’s peak reading accurately.

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 Review 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 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.

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.