Highest temperature in Wellington on July 21?

Platform comparison

Market context

Wellington’s highest temperature on 21 July 2026 is being priced as virtually certain to land at 12°C, with the crowd assigning a 100% probability to that single outcome and zero chance to anything at or below 7°C. The market’s current YES probability for any alternative range sits at 0%, reflecting near-total consensus that mid-12s Celsius is the expected peak for the day at Wellington International Airport.

Historically, late-July highs in Wellington typically cluster between 10°C and 14°C, with 12°C representing the median peak over the past decade at the NZWN station. Extreme outliers below 8°C are rare, usually tied to strong polar airflows, while spikes above 16°C almost never occur without a sustained nor’wester. Given this stability, the 100% weighting on 12°C appears well-supported by climatology, though the lack of any spread leaves little room for value unless a sudden shift in wind pattern emerges.

Traders should monitor the Bureau of Meteorology’s 72-hour forecast for the Tasman Sea, particularly any development of a nor’wester ridge that could push temperatures toward 15°C, or a polar trough that might dip them to 9°C. A recent MetService bulletin notes that July 2026 has seen more frequent southerly surges than average, increasing the risk of a cooler-than-expected peak [1]. If the forecast shifts toward either extreme, the 0% implied probability on lower ranges could offer contrarian value, but until then, the favourite remains firmly at 12°C.

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

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.

FAQ

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.

Do I need to KYC for this market?

On Polymarket directly, no — it's wallet-based. Intermediary brokers like Who Will Win 2026 trigger KYC only above $1,500 of lifetime trading volume; under that you trade pseudonymously with a single wallet address.

How reliable are the quoted odds?

The YES/NO percentages are the live mid-prices of the Polymarket order book. On deep markets they move every few seconds; on thinner ones you'll see short plateaus.