Highest temperature in Sao Paulo on August 7?

Platform comparison

Market context

The event is whether the **highest recorded temperature** at São Paulo-Guarulhos International Airport on 7 August will fall into the market’s Celsius band, using the Weather Underground **Daily Observations** table as the settlement source rather than the summary high/low box. In practical terms, a **YES share** pays out if the final reported peak lands in the chosen range, while a **NO share** pays if it does not. With the market currently implying **0% YES**, traders are effectively saying the observed maximum is extremely unlikely to end up in the targeted range. [1]

To read that pricing, it helps to compare it with São Paulo’s usual August pattern. Forecast services and local summaries place daytime highs around the mid-20s Celsius, with one local brief calling for a high near **25°C** and no rain, while longer-run climate pages also point to August highs near **25°C** and cooler nights. Recent station-style monitoring for the city has shown highs around the mid-20s, which makes a sub- or mid-20s outcome more plausible than an unusually hot spike, especially if cloud cover or a cooler air mass limits warming. [5][8][11][13]

For traders, the main things to watch are the live station observations and any late changes in the day’s weather pattern before the settlement cut-off. Because the market settles on the **observed** temperature in the Daily Observations table, not the headline “Day High & Low” figure, a late-day update, revision, or an extra observation published before the next date’s first datapoint can matter more than a broad forecast. At 11:00 UTC, the key question is whether the airport station still has enough daytime heating left to move the final maximum into the relevant band before the market closes. [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.

UK Frequently Asked Questions

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.

Is Polymarket legal in the UK?

Polymarket is accessible to UK traders but is not UKGC-licensed. It operates under US CFTC jurisdiction. UK residents face no domestic legal prohibition on using it, but UKGC consumer protections do not apply. For UKGC-regulated alternatives, Betfair Exchange and Smarkets offer similar prediction-style markets.

Do I pay tax on prediction market profits in the UK?

UKGC-licensed platform profits (Betfair, Smarkets) are typically tax-free gambling winnings for UK individuals. Polymarket profits involve USDC crypto transactions, which HMRC treats as Capital Gains Tax events. Keep full transaction records and report via Self Assessment if gains exceed £3,000 per tax year.

How do I deposit on Polymarket from the UK?

UK traders typically fund Polymarket via Coinbase UK, Kraken or Revolut — buying USDC with GBP and transferring to a Polygon-compatible wallet (MetaMask, Coinbase Wallet). Polymarket's onboarding walks you through the bridging process. Typical GBP-to-USDC conversion costs 0.5–1%.