Highest temperature in Wellington on July 20?

Platform comparison

Market context

On 20 July 2026, the highest temperature recorded at Wellington International Airport will determine the outcome of a weather prediction market. A YES share means you believe the temperature will fall within a specific range, while a NO share means you expect it to fall outside that range. In this case, the crowd currently assigns a 0% probability to the market resolving as YES for the 12°C range, despite forecasts suggesting 12°C is the most likely high for the day.

Historical July temperatures in Wellington typically hover between 6°C and 13°C, with 12°C being a common peak during clear winter days. The current 0% implied probability for the 12°C outcome appears inconsistent with both seasonal norms and current forecast models, which position 12°C as the most probable high with a 58% implied probability on competing platforms. This divergence suggests either a data lag in crowd sentiment or a misunderstanding of the resolution criteria among traders.

Traders should monitor real-time updates from Wunderground, the official resolution source, as temperatures are recorded throughout the day and finalised only after the last datapoint for 20 July is published. Any revisions to recorded temperatures before the first datapoint for 21 July will be considered, meaning early readings may shift before settlement. With the settlement window closing at 12:00 UTC on 20 July 2026, timely access to live weather data from NZWN will be critical for assessing whether the market’s current pricing reflects reality or an anomaly.

Sources: 1

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.

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 Prediction Market 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.

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.

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.