Highest temperature in Tokyo on July 6?

Platform comparison

Market context

The underlying event is the peak daytime heat recorded at Tokyo Haneda Airport on 6 July 2026, a date that historically sits within Tokyo’s hottest month. While the current prediction market shows a 0% implied probability for a “YES” outcome on a specific low-temperature threshold, this figure diverges sharply from cross-platform odds. Polymarket, for instance, assigns a 47% chance to a high of 26°C and 39% to 25°C, suggesting the crowd expects a warm day rather than a cool one. This stark contrast between the 0% line and the 47% frontrunner on another platform highlights a meaningful pricing inefficiency or a misaligned contract definition that traders must scrutinise before taking a position.

Historical July data frames this expectation firmly: AccuWeather forecasts daily highs in Haneda for July 2026 between 79°F and 89°F (roughly 26°C to 32°C), with an average high of 87°F. Recent records reinforce this trend, as Japan just experienced its warmest day on record with 41.2°C in Tamba city, and a previous July saw over 120 heatstroke deaths in Tokyo due to record temperatures averaging 2.16°C above the 30-year norm. These comparable cases indicate that a low-temperature outcome is statistically improbable, making the 0% market line appear inconsistent with the broader climatic reality and the more aggressive pricing on Polymarket.

Traders should monitor the Japan Meteorological Agency’s daily forecasts and any sudden shifts in the Pacific High pressure system, which drives summer heat in the region. The settlement relies on Wunderground data for the Haneda station, so real-time updates from that source are critical. Recent news from Denver7 notes that July 2025 was exceptionally hot, suggesting a potential continuation of extreme heat patterns into 2026. With the settlement window ending at 12:00 UTC on 6 July, the key dependency is the precise timing of the daily temperature peak, which typically occurs between 14:00 and 15:00 local time, ensuring the market resolves on the true maximum rather than an early morning dip.

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 Best Prediction Markets. 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.

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.

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.