Lowest temperature in Hong Kong on August 8?

Platform comparison

Market context

Polymarket is pricing this contract at **0% YES** for the lowest temperature in Hong Kong on 8 August, so the market is effectively saying a realised HKO minimum inside the listed range is not expected at present. The event resolves on the Hong Kong Observatory’s finalised “Absolute Daily Min (deg. C)” for that date, and the contract is settled in USDC on Polygon through conditional tokens, so the practical question for holders is whether the published daily extract lands in one of the available temperature bands once the observatory posts the final data.[9][4]

For context, Hong Kong’s August climate is usually warm and humid rather than cool: HKO normals for 8 August show an average minimum of 26.9°C, while other August climate summaries put typical lows around 26–27°C and rarely below that.[1][16] That matters because this market is not about an extreme citywide cold snap in the abstract; it is about the single lowest reading recorded at the Observatory station, which can differ from broader city weather and can still move a few tenths on a given morning. The current 0% price therefore implies traders see the observed minimum as likely to sit outside the contract’s relevant range, rather than near the seasonal norm.[1][16]

The key catalysts are the HKO’s hourly readings, any late-night or early-morning rain bands, cloud cover, and the timing of the final “Daily Extract” publication, because settlement cannot happen until the date’s data is published.[14][9] Early on 8 August, the Observatory had already reported 29°C at 3 a.m., with 27–30°C readings across other Hong Kong stations, which points to a sticky overnight profile rather than a sharply cooler one.[14] Polymarket’s own event page also notes that revisions after initial publication are ignored for resolution, so the only data that matters is the final HKO extract for the settlement date.[4]

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.

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.

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%.