Highest temperature in Tokyo on July 31?

Platform comparison

Market context

Tokyo’s outcome will be set by the highest temperature recorded at Haneda on 31 July, with the market resolving on a Celsius range from Wunderground rather than on the citywide maximum. At 7am UTC, the crowd is still pricing **0% YES**, which is consistent with the fact that the settlement window closes later in the Tokyo day and the value can only be fixed once the daily high has actually been observed. JMA station data show Haneda has been running in the low 30s °C on recent July days, including 31.1°C on 31 July 2025, which is warm but well below the extreme 40°C-plus readings seen elsewhere in Japan this month.[8][9]

For framing, recent comparables argue against over-reading Tokyo’s broader heat headlines: Tokyo’s official station climate statistics put July averages around the low 30s °C at the hottest end, while the city’s historic all-time maximum cited by weather aggregators is 37°C, far above a typical late-July day but still not a level Haneda reaches often.[12][6] That makes the upper bands on this market less likely unless a sharp, localised heat spike develops around Haneda specifically. On Polymarket, the crowd probability is the cleanest read; on Kalshi or Betfair, the same event would usually be expressed as a price or decimal odds, so a thinly traded move can look visually different even when the underlying expectation is similar. Fee treatment also diverges: exchange-style books such as Betfair and Smarkets surface commission more explicitly, while platform rules and KYC reach can affect who is able to enter or scale a position.

The key catalysts are straightforward: Tokyo’s daytime heating profile, cloud cover, and any marine breeze off Tokyo Bay, because Haneda sits on reclaimed coastal land and can behave differently from inland Tokyo stations. The market is also sensitive to the precise Wunderground daily maximum for the Haneda Airport Station, so late-afternoon observations matter more than early-morning readings. With Japan in a period of exceptional heat and national records still being rewritten this week, traders will watch whether that broader warmth translates to Haneda or stays concentrated further inland.[9][14]

Sources: 1 · 2 · 3 · 4 · 5

Methodology

We read Highest temperature in Tokyo on July 31? from four platform perspectives: Polymarket (on-chain CLOB), Kalshi (CFTC-regulated exchange), Betfair Exchange (sports book exchange), Smarkets (peer-to-peer betting exchange). Polymarket's live mid is the canonical probability; the side-by-side columns benchmark fees, KYC, settlement currency and deposit rails so you can choose the venue that fits your jurisdiction and trade size.

Resolution & payout

Polymarket settles via UMA Optimistic Oracle on Polygon. A proposer posts the outcome with a bond, the two-hour window runs, then the smart contract pays USDC.

Kalshi settles USD through the CFTC-regulated clearinghouse — the cleanest variant, with heavier KYC. Betfair Exchange settles in account currency (GBP/EUR), net of 2-5% commission. Smarkets follows the same model as Betfair with a lower default 2% commission.

FAQ

Polymarket vs Kalshi — which is better?

Depends on your location. Kalshi is CFTC-regulated, US-only with full KYC. Polymarket is global, on-chain, no KYC up to $1,500. Polymarket has ~10x higher liquidity but higher regulatory risk.

Is Betfair a Polymarket alternative?

Only partially. Betfair Exchange is UK-focused with a sports-betting emphasis; they have politics markets but with thinner liquidity than Polymarket. Settlement in GBP/EUR, 2-5% commission on winnings.

What about Smarkets as an alternative?

Smarkets is a UK betting exchange with a lower default commission (2%) than Betfair. Liquidity on political markets is below Polymarket, comparable to Kalshi. Geo-blocked in many jurisdictions.

Which platform is accessible globally?

Polymarket is geo-blocked in the US/UK/EU. Kalshi is US-only. Betfair and Smarkets are UK-restricted. Robinhood Prediction Markets has a different geo footprint and routes to Polymarket's order book at 0% fees.

Are all these platforms regulated?

No. Kalshi is CFTC-regulated (US). Betfair and Smarkets are UK Gambling Commission licensed. Polymarket operates without explicit regulation — a different risk profile than a regulated sportsbook.