Highest temperature in Sao Paulo on July 6?

Platform comparison

Market context

The underlying event is the peak temperature recorded at São Paulo-Guarulhos International Airport on 6 July 2026, a date climatologically anchored as the coldest period of the Brazilian year. Historical averages for early July in São Paulo sit between 21–22 °C, with typical highs rarely exceeding 25 °C unless an anomalous heatwave intervenes [1]. While July 2023 broke records as the hottest July in 174 years, those extremes were driven by broader continental patterns that have not yet re-emerged in 2026 [6]. The current crowd-implied probability of 0% for a "YES" outcome (likely meaning a temperature above a specific threshold) suggests the market views any extreme deviation as statistically negligible, aligning consensus with the narrow 24–25 °C band where model guidance places the expected high [1].

Traders should monitor real-time atmospheric dependencies, particularly the strength of the South Atlantic Convergence Zone and any sudden shifts in wind patterns that could trap heat near the airport station. Recent reports from Rio de Janeiro indicate isolated heat indices reaching 52.7 °C, but these are coastal anomalies unlikely to translate to the inland, elevated climate of São Paulo without a significant synoptic shift [5]. The value spot may lie contrarian to the 0% pricing if a forecasted cold front fails to materialise, potentially pushing temperatures toward the upper tail of the 24–25 °C consensus rather than the lower average [1]. With settlement ending 12:00 UTC on 6 July, the final data point from Wunderground will resolve the market, making live model updates the critical catalyst for any late-positioning [1].

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

Polymarket-based markets settle through the UMA Optimistic Oracle on Polygon. A proposer submits the outcome, a two-hour challenge window opens, and unchallenged proposals finalise the resolution. Payouts settle automatically in USDC the moment the result is final — no bookmaker, no delay.

Kalshi-based markets settle in USD via the CFTC-regulated clearinghouse. Betfair Exchange settles in GBP/EUR net of commission. Manifold is play-money and does not pay out real funds.

FAQ

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.

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 Who Will Win 2026 trigger KYC only above $1,500 of lifetime trading volume; under that you trade pseudonymously with a single wallet address.