Highest temperature in Tokyo on July 31?

Platform comparison

Market context

Tokyo Haneda Airport’s highest temperature on 31 July will be the settlement print, so the key question is whether the airport station posts a day’s maximum that falls into the market’s bands before the noon UTC cut-off. Tokyo’s July climate is already warm and humid, with July averages around 30°C at city level and recent July highs frequently reaching the low-to-mid 30s, while Haneda itself has logged daily maxima around 31–32°C on late-July days in recent JMA data.[12][7]

For probability calibration, the market’s 0% YES looks like a stale crowd read rather than a meteorological claim: Tokyo rarely needs extreme heat to clear common summer thresholds, but hitting the very top bands depends on an actual afternoon spike at Haneda, not just the broader city temperature. Comparable late-July Tokyo readings over recent years show Haneda often underperforming inland wards, while Tokyo-wide records and Japan’s national heat extremes sit much higher, including the country’s new 41.2°C record in Hyogo in July 2025 and Tokyo’s own historical highs near 37°C.[8][10][5]

A programmematic approach would treat this as a live data-integration problem: poll the Wunderground Haneda history page, normalise Celsius, and map the day’s maximum against the market’s settlement ranges, with retries around local afternoon convection and any late station update. Traders should watch the Tokyo forecast, the synoptic setup over eastern Japan, and any heat advisories or extraordinary weather developments from Japanese official or wire coverage, because a stable high-pressure ridge can push airport temperatures up quickly while cloud, sea breeze, or rain suppresses the maximum.[4][16]

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

At resolution the UMA oracle takes over: a proposer posts the outcome with a bond, any token holder can dispute within two hours. Without dispute the result is accepted and the smart contract distributes USDC instantly.

On Kalshi (CFTC-regulated) resolution runs through their in-house clearing engine in USD. Betfair Exchange settles after match end in the account's local currency. Manifold pays no cash — only its in-platform "mana" currency.

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 Polymarket Review UK. 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.

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 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.