Highest temperature in Tokyo on July 5?

Platform comparison

Market context

On 5 July 2026, the Tokyo Haneda Airport Station will record its peak temperature, a real-world event that determines the resolution of a weather-based prediction market. While one platform currently implies a 0% chance for the highest temperature to exceed 21°C, this contradicts active trading data on Polymarket, where the frontrunner is 27°C at 54% probability, with 26°C holding 44%. This divergence highlights how implied probability on some exchanges can mask decimal odds realities seen elsewhere, where liquidity suggests a near-certainty of summer heat rather than the cool anomaly implied by the 0% figure.

Historical July data for Haneda confirms daily highs typically range between 26°C and 29°C, with overnight lows rarely dropping below 22°C, making the 0% implied probability statistically fragile. Recent records support this thermal baseline; Tokyo reached 36.8°C on 1 July 2026, marking the highest temperature ever recorded for that date in the city, while Japan’s overall summer record hit 41.2°C in Tamba city earlier this year. Traders should monitor the Japan Meteorological Agency’s weekly heat advisories and any scheduled cooling announcements, as these dependencies directly influence peak temperatures, with recent news confirming the immediate arrival of Japan’s 2026 summer heatwave.

Platform mechanics further complicate the reading of this market, as fee structures and KYC requirements vary significantly between Polymarket, Kalshi, and Betfair. Polymarket’s permissionless access and lower fees attract higher volume, allowing decimal odds to reflect true market sentiment, whereas regulated platforms like Kalshi may impose stricter KYC that dampens liquidity and skews implied probabilities. The 0% figure on one book likely stems from a lack of active participants rather than meteorological evidence, whereas the 54% probability on Polymarket aligns with the 26–27°C range observed in both forecast models and recent historical extremes.

Sources: 1 · 2 · 3 · 4 · 5

Methodology

This page compares Highest temperature in Tokyo on July 5? specifically across Polymarket, Kalshi, Betfair Exchange and Smarkets. The live probability is the Polymarket mid; the comparison columns summarise each venue's fee structure, KYC, settlement currency and payment rails. Every CTA routes to Robinhood Prediction Markets, which mirrors the Polymarket order book at 0% fees.

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.

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.

Which platform has the deepest liquidity?

Polymarket — by a wide margin. Top markets reach $50-500M volume, Kalshi ~$200M cumulative, Betfair similar. Deeper liquidity means your trade moves the quote less.

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.

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.