Highest temperature in Tokyo on July 4?

Platform comparison

Market context

The underlying event is the peak daily temperature recorded at Tokyo Haneda Airport on 4 July 2026, measured in degrees Celsius via Wunderground. Current crowd-implied probability for a 26°C or lower outcome sits at 0% YES, reflecting market consensus that such a low reading is virtually impossible given the season. Historical data frames this probability starkly: mid-to-late July in Tokyo routinely sees highs between 36°C and 40°C with humidity exceeding 95%, creating a concrete jungle environment where heat persists even after sunset [3]. Recent records reinforce this trend, with Japan hitting its highest-ever temperature of 41.2°C in Tamba City on 30 July 2025, breaking multiple heatwave records since 1898 [9][10]. The current Polymarket frontrunner is 27°C at 57%, while 26°C holds only 26%, confirming that traders expect temperatures well above the 26°C threshold [1].

A programmatic trader would approach this market by querying Wunderground’s historical API for RJTT (Haneda) to establish baseline July 4 distributions, then overlaying real-time meteorological feeds for anomaly detection. Key catalysts to monitor include the Japan Meteorological Agency’s daily heatwave advisories and any sudden shifts in Pacific high-pressure systems, which directly dictate peak temperatures. Recent news confirms Japan experienced its hottest July since records began, with temperatures soaring past 41°C in several cities, suggesting a high-probability environment for extreme readings [10]. Traders should also watch for scheduled maintenance at Haneda’s weather stations, as data gaps could delay resolution, and verify that Wunderground’s source data aligns with official JMA records to avoid settlement discrepancies. The 2026-07-04T12:00:00Z settlement window allows ample time for data aggregation, but conditional orders should trigger only if real-time feeds confirm temperatures exceeding 30°C, as historical averages for Haneda in July range from 76°F to 91°F (24°C–33°C) [5].

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 Polymarket Bot 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 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.