Highest temperature in Sao Paulo on June 30?

Platform comparison

Market context

The real-world event driving this market is the peak daily temperature recorded at São Paulo-Guarulhos International Airport on 30 June 2026, measured in degrees Celsius. This date falls squarely within the Southern Hemisphere’s winter, historically the coldest period for the region, which explains the crowd-implied 0% probability for any high-temperature outlier.

Historical data frames this probability with clarity: June and July are São Paulo’s coldest months, averaging highs of just 21.8°C (71.2°F), with temperatures rarely exceeding 29°C (83°F) even on warm days [3][6]. Recent records show the highest temperature in the last 15 days was 78.8°F (26°C) on 22 June, while the lowest dropped to 48.9°F (9.4°C) on 18 June [2]. Even the city’s highest December temperature, a summer peak of 35.9°C, remains an anomaly far outside winter norms [5]. Programmatically, a trader would model this using seasonal regression, filtering for winter baselines and excluding summer extremes as irrelevant noise.

Traders should monitor meteorological bulletins for unexpected heatwave forecasts or atmospheric anomalies, though none are currently anticipated. Key dependencies include the official Wunderground dataset release at 12:00 UTC on 30 June, which will confirm the final resolution [1]. While no recent news source predicts a winter heat spike, the PredictWind historical archive for June 2026 offers granular daily averages to validate baseline expectations [7]. A power-user would script a conditional order to close positions if Wunderground’s preliminary data shows temperatures above 28°C, treating such a signal as a statistical outlier requiring immediate re-evaluation.

Sources: 1 · 2 · 3 · 4 · 5

Methodology

We track Highest temperature in Sao Paulo 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

At resolution the UMA oracle takes over: a proposer posts the outcome with a bond, any token holder can dispute within two hours. Without dispute the result is accepted and the smart contract distributes USDC instantly.

On Kalshi (CFTC-regulated) resolution runs through their in-house clearing engine in USD. Betfair Exchange settles after match end in the account's local currency. Manifold pays no cash — only its in-platform "mana" currency.

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 Kalshi Fees. Kalshi charges up to 7% per trade; Betfair Exchange takes 2-5% commission on net winnings.

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'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.

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.