Highest temperature in Tokyo on June 30?

Platform comparison

Market context

The underlying real-world event is the highest temperature recorded at Tokyo Haneda Airport on 30 June 2026, measured in whole degrees Celsius by Wunderground. Today, Polymarket prices the YES contract for a 24°C threshold at 0%, implying the crowd believes the temperature will far exceed this mild figure. This on-chain pricing reflects the conditional token mechanics on Polygon, where USDC liquidity is locked against the outcome, and the market will only resolve once the first data point for that date is published on the resolution source.

Historical precedents frame this near-zero probability as rational rather than speculative. June in Tokyo typically sees average highs around 26–27°C, with recent years recording extreme heatwaves; for instance, Japan hit a record 41.2°C in July 2025 after the hottest June on record, and Tokyo logged 36.4°C in a record-breaking June 147 years ago [5][8]. Even the 2026 AccuWeather forecast for Haneda predicts daily highs between 24°C and 28°C, with an average of 26°C, making 24°C a plausible low bound but not the peak [3].

Traders should monitor the Japan Meteorological Agency’s daily heatwave bulletins and any sudden shifts in the Pacific high-pressure system, which drives summer temperatures in the region. While no specific announcement is scheduled for 30 June, the weather agency’s recent report on Tokyo’s record 10 consecutive days above 35°C underscores the volatility of summer heat [10]. With the settlement window ending 2026-06-30T12:00:00Z, the market’s resolution hinges entirely on the Wunderground data point, which measures temperatures to whole degrees and will not accept revisions after the first datapoint is published [1].

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

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

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 PolyGram. 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 fast are USDC deposits?

Polygon credits deposits after 12 confirmations — usually under 30 seconds. Withdrawals follow the same path and land back in your wallet within minutes.