Highest temperature in Tokyo on June 30?

Platform comparison

Market context

The real-world event hinges on whether Tokyo Haneda Airport will record a temperature exceeding 30°C on 30 June 2026, a threshold that marks the onset of the city’s intense hot season. Historical data confirms that late June is typically the transition point where daily highs climb above 79°F (26.1°C), with the average high for the month sitting at 80°F (26.7°C)[5][7]. Recent observations from mid-June 2026 show peaks reaching 82.7°F (28.2°C), yet no day has breached the 30°C mark in the past fortnight[9]. This pattern suggests the current crowd-implied probability of 0% YES is statistically grounded, as the consensus correctly identifies that the 30°C barrier is rarely crossed before the final week of June, making the underdog (YES) a value spot only if an unseasonal heatwave materialises.

Traders should monitor the National Weather Service’s hourly forecasts for Tokyo Haneda, specifically watching for any sudden shifts in the jet stream or the arrival of a Pacific high-pressure system that could trigger a rapid temperature spike[2]. While no specific weather announcements have been issued for 30 June yet, the AccuWeather forecast for Haneda indicates daily highs ranging from 75°F to 83°F (23.9°C–28.3°C), which remains below the 30°C threshold[5]. The key dependency is the timing of the hot season’s official start, which historically begins on 29 June; if the 2026 season arrives earlier than usual, the contrarian angle of betting YES could gain traction, though current data suggests the probability remains negligible until the heatwave intensifies[7].

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

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 Who Will Win 2026. 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.

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.