Highest temperature in London on July 10?

Platform comparison

Market context

On 10 July 2026, London City Airport will record its peak temperature for the day, a single data point that determines the outcome of a prediction market resolving to a specific Celsius range. The current crowd-implied probability of 0% for the "YES" outcome suggests traders believe the temperature will fall outside the targeted bracket, likely due to expectations of sweltering heat pushing readings higher than anticipated. This market resolves via Wunderground data from the EGLC station, with the settlement window closing at 12:00 UTC on the day itself.

Historical context frames this 0% probability as potentially premature. July is London’s hottest month, with London City Airport averaging a high of 72°F (22°C), yet extreme heatwaves have shattered norms; in July 2022, several UK airports recorded 40°C for the first time, and recent analysis notes the intense heatwave of July 2025 was particularly noteworthy for its intensity across the British Isles[7][10]. Current forecasts for 10 July show "very warm" conditions with highs near 86°F (30°C) and minimal rain, indicating a scenario where temperatures could easily breach standard ranges, making the 0% probability a contentious bet against historical volatility[3].

Traders should monitor the Met Office’s 7-day forecast and real-time Wunderground updates, as sudden shifts in southerly winds or cloud cover could alter the peak temperature significantly[2][5]. The divergence between platforms like Polymarket, which uses implied probability, and Kalshi or Betfair, which often quote decimal odds, creates arbitrage opportunities if one book misprices the heat risk; similarly, fee structures and KYC requirements vary, with some platforms requiring identity verification while others remain open, affecting liquidity depth on this specific weather event[1]. No moralising is needed; the facts show a high-heat day where the 0% probability may underestimate the likelihood of extreme temperatures.

Sources: 1 · 2 · 3 · 4 · 5

Methodology

This page compares Highest temperature in London on July 10? 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 Polymarket Alternative, 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.

Which platform is accessible globally?

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

Which platform supports Klarna/SOFORT?

Directly: none. Polymarket accepts only USDC on Polygon. Polymarket Alternative 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.