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 a prediction market where the crowd currently assigns zero probability to any “YES” result. This event hinges on a single day’s peak heat in a city where June is historically mild, cool, and breezy, with average highs of 23°C and lows of 13°C[1]. The settlement depends exclusively on Wunderground’s official daily high for that station, measured in degrees Celsius.

Historically, June in São Paulo rarely produces extreme heat; the coldest month is July, with average highs of just 22°C[3]. Even the city’s hottest recorded day—38.5°C—occurred in November 2023, not in winter months[5]. The most recent peak in June 2026 was 26°C on 22 June[2], far below thresholds that would trigger a “YES” outcome. This consistent pattern explains why prediction-market implied probability sits at 0%, diverging sharply from any sportsbook line that might offer odds on marginal heat events, and aligning with analyst consensus that winter highs in São Paulo remain well below 30°C.

Traders should monitor real-time Wunderground updates for 30 June, as well as any sudden shifts in regional wind patterns or cloud cover that could elevate temperatures unexpectedly. While no major weather announcements are scheduled, the 11.3 mph average wind speed in June typically suppresses heat buildup[1]. A trader must also verify whether the station’s sensor calibration remains consistent, as minor discrepancies could alter the recorded peak. Recent climate data confirms that June 2026 has so far shown no anomalous heat spikes, reinforcing the zero-probability stance[7].

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

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.

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 PolyGram 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.