Highest temperature in Wellington on July 20?

Platform comparison

Market context

Wellington is experiencing a cold, windy July day with temperatures hovering near 12°C and strong northerly gusts, pushing the market’s implied probability for any outcome above 12°C to zero. Current forecasts position 12°C as the most probable high for 20 July 2026, aligning with the market’s leading 58% implied probability for that specific range, while the crowd assigns 100% certainty to 12°C being the exact high [1]. Real-time observations from the Wellington International Airport station confirm a current temperature of 12.2°C with 33km/h northerly winds, reinforcing the likelihood of a cool maximum rather than a warm spike [3].

Historical July patterns in Wellington show daily highs typically ranging between 51°F and 58°F (10.5°C–14.4°C), with the average high sitting at 55°F (12.8°C), making a 12°C peak consistent with seasonal norms rather than an outlier [6]. The 0% YES probability for higher temperatures reflects the prevailing cold snap conditions described in NIWA’s seasonal outlook, which notes occasional cold snaps are possible under persistent high pressure, particularly with southerly-quarter flow anomalies expected early in the period [8]. This aligns with the current 100% market confidence in 12°C, suggesting traders view any deviation above this as highly improbable given the active cold air mass.

Traders should monitor updates from MetService and NIWA for shifts in wind direction or pressure systems, as a transition to southwesterly flow characteristic of El Niño conditions could alter temperature trajectories later in the week [8]. AccuWeather forecasts high winds with gusts past 45 mph from Thursday into Saturday, which may sustain cooler conditions and limit solar heating [5]. Any announcement of a rapid ENSO transition or unexpected pressure drop could act as a catalyst, though current data suggests the cold, windy regime will persist through settlement.

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.

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 Today. Kalshi charges up to 7% per trade; Betfair Exchange takes 2-5% commission on net winnings.

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 Prediction Today 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.