Highest temperature in Tokyo on August 8?

Platform comparison

Market context

Tokyo’s highest reading on 8 August will come from the Weather Underground Daily Observations table for Haneda Airport Station, so traders should focus on the actual station report rather than any summary high/low banner. Polymarket currently shows a tight cluster around the mid-30s Celsius, with 34°C leading at 50% and 33°C at 34%, which is consistent with Tokyo’s August climatology and the possibility of a brief peak above the daily mean rather than an extreme outlier.[1][6][12]

For comparison with other books, Polymarket displays the market in **implied probability**, while Kalshi and Betfair-style books are usually easier to read in **price terms** or decimal odds, so a near-coin-flip outcome can look different even when the underlying view is similar. The current 0% YES on Robinhood-style framing is therefore not a weather forecast in itself; it reflects how the contract is priced, and fees, spreads and access rules can vary materially across venues, with Betfair’s exchange model and Smarkets’ lower-commission structure often making them feel closer to trading books than fixed-odds sites.[1]

The main catalysts are the day’s actual temperature path, not a calendar event: morning cloud cover, sea breeze, and any late-afternoon convective burst will affect whether Haneda reaches 33°C, 34°C or higher. Recent Japanese heat reporting shows how quickly readings can spike during summer surges, with 2025 setting multiple record highs nationally, so a warm synoptic pattern keeps the upper tail open even when the market’s centre of gravity sits around 33–34°C.[15][18] Traders should also watch the timing of the first post-midnight observation on 9 August, because the market settles only after that datapoint is published.[1]

Sources: 1 · 2 · 3 · 4 · 5

Methodology

We read Highest temperature in Tokyo on August 8? 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

What does Polymarket cost vs Kalshi?

Polymarket: 0% fees, only Polygon network costs (~$0.01/trade). Kalshi: up to 7% per trade plus spread. For high-frequency traders, Polymarket is dramatically cheaper.

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.

Which platform supports Klarna/SOFORT?

Directly: none. Polymarket accepts only USDC on Polygon. Robinhood Prediction Markets offers a fiat on-ramp via Klarna or SOFORT (DE/AT/CH) and converts internally to USDC for the Polymarket order book. T+1 processing.