Highest temperature in Sao Paulo on July 6?

Platform comparison

Market context

On 6 July 2026, the Sao Paulo-Guarulhos International Airport Station will record its peak temperature for the day, a single real-world data point that determines the outcome of a weather-based prediction contract. While one market shows a 0% implied probability for the “YES” outcome, this divergence stems from a mismatch in resolution criteria rather than a genuine forecast of freezing conditions. Historical patterns for early July in São Paulo consistently place maximums between 21°C and 26°C, with long-term averages centring near 22–24°C. Polymarket traders, using a different temperature band, currently assign 50% probability to 24°C and 21% to 25°C, reflecting strong consensus that the day will be mild but not extreme.

The key catalyst for traders is the arrival of the first heat wave of 2026, which forecast models suggest could push temperatures as high as 38°C across parts of Brazil, though São Paulo’s urban microclimate may moderate this spike. A recent warning from PredictWind highlights that this event is expected to begin in the coming days, making weather model updates and local meteorological bulletins critical for assessing whether the airport station will breach the 24–25°C range. Analysts note that while Rio de Janeiro recently recorded perceived temperatures of 62°C during a severe heat wave, São Paulo’s winter highs typically remain lower, clustering between 21°C and 26°C. Traders should monitor Wunderground’s daily updates and AccuWeather’s July forecast, which indicates daily highs ranging from 64°F to 77°F, to gauge whether the 0% market line represents a genuine outlier or a structural misalignment in contract terms.

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

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 Best Prediction Markets. 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.

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

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.