Highest temperature in Sao Paulo on August 7?

Platform comparison

Market context

Polymarket is pricing **25°C at 30%**, with **26°C at 23%** and **27°C at 19%**, so the contract is still centred on a fairly tight winter daytime range even though settlement will be driven by the highest reading in Weather Underground’s daily observations for São Paulo-Guarulhos Airport, not a summary high/low panel.[3] On the current order book, the crowd is effectively saying that a mid-20s Celsius peak is the most likely outcome, which is consistent with a liquid Polygon-based conditional token market that can reprice quickly as fresh weather data and late trades arrive.[3]

That distribution is broadly in line with São Paulo’s August climatology, where long-run averages point to daytime highs around 23–25°C and daily highs that rarely push much above the mid-20s in normal winter conditions.[2][5][6][13] Comparable forecast sources for 7 August also cluster near 25–26°C, with one daily brief showing 25°C and another forecast putting the day near 25–29°C, which helps explain why the market has stayed anchored around 25°C rather than shifting materially higher.[7][9][10] The key practical point for resolution is that the outcome depends on the *single highest observed temperature* logged for the airport station before the settlement cutoff, so a brief late-afternoon spike or a data revision can matter more than the headline daily forecast.[3]

A trader should watch the Weather Underground history page for São Paulo-Guarulhos as observations come in, because the market rules allow revisions until the first datapoint for the following date is published.[3] For Polymarket users holding USDC on Polygon, that means the token price is still sensitive to the final hours of the local day and any post-observation updates that could move the recorded maximum from 25°C into 26°C or 27°C territory.[3] With the market currently concentrated on the lower end of that band, the main catalyst is not a macro announcement but the actual station trace as temperatures crest and then cool.

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.

UK Frequently Asked Questions

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 PolyGram. 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.

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%.