Highest temperature in Tokyo on August 20?

Platform comparison

Market context

The Tokyo Haneda Airport weather station will record a daily maximum temperature on 20 August 2026, with traders currently assigning zero probability to any outcome. This represents an unusual market state given that August temperatures in Tokyo are historically well-documented and predictable within established ranges. The settlement mechanism relies specifically on Weather Underground's Daily Observations table rather than summary figures, a distinction that matters when automated systems and manual records occasionally diverge.

Tokyo's August climate shows consistent patterns across decades. The Japan Meteorological Agency records indicate that daily highs in mid-August typically fall between 32°C and 36°C, with extremes occasionally reaching 37–38°C during heat waves. The 2010 heat wave saw Tokyo record 40.0°C, though such events remain statistical outliers. Recent Augusts (2022–2024) have produced daily maxima clustering around 33–35°C at Haneda, suggesting the market's zero probability reflects either technical setup issues or extreme confidence in a narrow temperature band that hasn't yet been defined in the market's range options.

Traders should monitor Japan Meteorological Agency forecasts released in early August 2026, which typically provide reliable 10–14 day outlooks for temperature patterns. La Niña or El Niño conditions active during northern summer can shift seasonal temperatures by 1–2°C. The specific resolution source—Wunderground's Daily Observations table at Haneda—requires verification against JMA official records, as discrepancies occasionally emerge between international weather platforms and national meteorological services. Any market activity should account for the settlement window closing at midday UTC, which may precede final temperature recordings depending on timezone conversion.

Methodology

We track Highest temperature in Tokyo on August 20? 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

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

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.

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.

Do I need to KYC for this market?

On Polymarket directly, no — it's wallet-based. Intermediary brokers like Best Prediction Markets 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.