Highest temperature in Tokyo on June 30?

Platform comparison

Market context

The underlying event is the highest temperature recorded at Tokyo Haneda Airport on 30 June 2026, a date that sits at the very start of Japan’s official hot season. Historical data shows June highs at Haneda typically range from 24°C to 28°C, with the average high near 27°C. While Japan has recorded extreme heat recently—41.2°C in Tamba city in July 2025 and 36.4°C in Tokyo during a record June in 2024—such peaks are rare in early June at Haneda. The current crowd-implied probability of 0% for any temperature above the highest bracket aligns with this pattern, as no credible forecast suggests Haneda will breach 35°C on this specific date.

Traders should monitor the Japan Meteorological Agency’s daily heatwave advisories and the timing of the hot season’s onset, which officially begins 29 June. A sudden shift in the Pacific high-pressure system could accelerate warming, but current AccuWeather forecasts for Haneda in June 2026 predict daily highs between 24°C and 28°C, with no indication of extreme heat. Recent news from Al Jazeera confirms Japan’s record-breaking heat in July 2025, yet this does not translate to early June conditions at Haneda. The divergence between sportsbook lines on extreme heat events and the 0% prediction-market probability reflects a clear consensus: Haneda’s early June climate remains moderate, and the settlement source (Wunderground) will likely confirm a temperature well below the highest bracket.

Sources: 1 · 2 · 3 · 4 · 5

Methodology

We track Highest temperature in Tokyo on June 30? across the five venues with material prediction-market liquidity. The probability shown is the live Polymarket mid; the comparison rows summarise how each venue treats the underlying contract — fees, KYC thresholds, settlement currency, deposit options. The highlighted row marks the cheapest route into Polymarket's order book.

Resolution & payout

Polymarket-based markets settle through the UMA Optimistic Oracle on Polygon. A proposer submits the outcome, a two-hour challenge window opens, and unchallenged proposals finalise the resolution. Payouts settle automatically in USDC the moment the result is final — no bookmaker, no delay.

Kalshi-based markets settle in USD via the CFTC-regulated clearinghouse. Betfair Exchange settles in GBP/EUR net of commission. Manifold is play-money and does not pay out real funds.

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.

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.

Do I need to KYC for this market?

On Polymarket directly, no — it's wallet-based. Intermediary brokers like Kalshi vs Polymarket 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.