Highest temperature in Sao Paulo on June 30?

Platform comparison

Market context

On 30 June 2026, the highest temperature recorded at Sao Paulo-Guarulhos International Airport will determine the outcome of a Polymarket contract priced at 0% YES today, reflecting the crowd’s certainty that the day will not exceed the upper threshold of the target range. This on-chain market, settled in USDC on Polygon using conditional tokens, hinges on a single real-world data point from Wunderground, making it a pure play on meteorological extremes rather than abstract speculation.

Historically, June in Sao Paulo is one of the coldest months, with average highs near 22°C and lows around 13°C, as July is the coldest month overall [3]. While Brazil recently recorded its national peak of 44.8°C during a stifling heatwave, that event occurred outside the winter season and in a different region [1]. Even during an unusual winter heatwave, temperatures in Sao Paulo reached close to 30°C (104°F), but such spikes are rare and short-lived [8]. The current 0% probability aligns with these patterns, suggesting the market expects a typical cool June day.

Traders should monitor the Brazilian National Meteorology Institute (INMET) for any sudden heatwave announcements or seasonal forecast updates, as these are the primary catalysts for temperature deviations. Recent reports confirm that winter heatwaves in Brazil can push temperatures above 30°C, but they remain infrequent and dependent on specific atmospheric conditions [8]. With the settlement window closing on 30 June 2026 at 12:00 UTC, the on-chain price will adjust only if INMET issues an official warning or if Wunderground data shows an unexpected spike, making real-time weather bulletins the critical dependency for this contract.

Sources: 1 · 2 · 3 · 4 · 5

Methodology

This page is a comparison snapshot: one live quote, four reference venues with their key attributes, and a single execution path — every trade button routes to Kalshi UK, which mirrors the Polymarket order book directly.

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

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 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.

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.

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.