Highest temperature in Wellington on August 21?

Platform comparison

Market context

Wellington's maximum temperature on 21 August 2026 will be determined by the strength of any cold front moving across the lower North Island during late winter. Currently, the market implies near-zero probability of temperatures exceeding the upper ranges, reflecting typical August conditions when Wellington rarely experiences warm days. The settlement will use Weather Underground's Daily Observations table from Wellington International Airport Station, which captures sub-hourly readings rather than the summary high-low figures, potentially capturing brief temperature spikes that the daily summary might miss.

August in Wellington historically produces daily maxima between 11–14°C, with extremes seldom exceeding 16°C. The 0% crowd probability suggests traders are pricing in expectation of a conventional late-winter day. However, the distinction between the Daily Observations granular data and the Day High & Low summary section creates resolution nuance; a rapid warming event or föhn-like conditions could register differently across these datasets. Traders should monitor MetService forecasts from mid-August onwards, particularly any warnings of unusual pressure patterns or northwesterly wind shifts that occasionally drive anomalous warmth into the region during this season.

The market's current pricing reflects confidence in typical winter behaviour, but late-winter weather systems can shift rapidly. Any significant forecast revision towards warmer conditions in the 48 hours before settlement would likely move probabilities. The specific reliance on sub-hourly observations means even brief warming episodes—rather than sustained high temperatures—could affect resolution outcomes.

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

Settlement runs on-chain. Polymarket's contract logic separates YES and NO shares as conditional tokens; at resolution the winning share lifts to $1.00 and the losing one to $0. The outcome input comes from the UMA Optimistic Oracle, which secures against bad resolution with a bond + dispute window.

Once finalised, the smart contract pays USDC to the holders' wallets within minutes — no withdrawal fees beyond Polygon network gas. Kalshi settles in USD via CFTC clearance, Betfair in account currency net of commission, Manifold in play-money mana with no cash-out.

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 Prediction Today. 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%.