Highest temperature in Tokyo on August 5?

Platform comparison

Market context

Tokyo’s afternoon high on 5 August is the real event, with the market now pricing a **0% YES** outcome for a specific temperature band even though consensus weather guidance still points to a normal midsummer reading rather than an extreme breakaway. JMA’s August data for Tokyo already show a hot start to the month, with Haneda printing **35.6°C** on 1 August and **33.0°C** on 2 August, while broader Tokyo forecasts cluster around the low 30s Celsius, which makes the current **underdog** pricing look anchored to an unusually narrow band rather than to the full heat-risk distribution.[1][2][11]

For handicapper framing, the favourite sits with the **29–31°C** cluster, where Polymarket shows the heaviest implied probabilities around **29°C (33%)**, **30°C (31%)** and **31°C (19%)**, so the market consensus is clearly for a warm but not exceptional day.[4] That leaves the more interesting value debate in the tails: a move above **32°C** is still plausible if the coastal station runs hot under strong sun and weak breeze, while a lower reading would usually require cloud, rain, or a sea-breeze cap on the maximum.[6][8] Recent reporting on Japan’s heatwave conditions underlines that elevated temperatures remain a live risk in early August, even if the exact Haneda print is often moderated by maritime influence.[5]

The main catalysts are straightforward and mostly meteorological: the morning-to-afternoon forecast trend, any cloud cover or shower signal over eastern Tokyo, and the timing of the sea breeze around the airport. Timeanddate’s hourly outlook for 5 August shows temperatures rising from the high 70s Fahrenheit overnight towards the upper 80s by late morning, with **0% precipitation chance** in that snapshot, which supports the market’s current bias towards a mid-30s-Celsius cap rather than a collapse in the maximum.[8] Traders should also watch for any updated JMA or airport-specific forecast shift before the midday UTC settlement window, because a small change in cloud, wind, or humidity can move the highest Haneda reading by a full degree band.[1][6]

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

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 Who Will Win 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.