Pronóstico: Highest temperature in London on June 30?

Platform comparison

Market context

The highest temperature recorded at London City Airport on 30 June 2026 will settle this market, with the current crowd-implied probability of a "YES" outcome sitting at 0%. On Polymarket, this contract trades on the Polygon network using USDC, where conditional tokens reflect the on-chain mechanics of the resolution source waiting for the first data point from Wunderground to be published. The market is priced today to indicate that no temperature range above the baseline is expected, despite the underlying real-world event occurring in late June, which is typically the start of London’s warm season.

Historical data frames this 0% probability as a conservative read rather than an absolute certainty. London City Airport’s warm season runs from 16 June to 8 September, with average daily highs exceeding 67°F (19°C), yet the hottest June day ever recorded in London reached 37.8°C at Heathrow, while recent observations at London City Airport show a daytime maximum of just 13°C on 30 June 2026 [2][4]. This stark contrast between the all-time record and the current 13°C reading suggests the market is correctly pricing in unsettled post-May conditions, similar to the 17°C maximum forecast for London on 6 June 2026 [1].

Traders should monitor the Met Office’s seven-day forecast for London City Airport and any sudden shifts in southerly wind patterns, which could trigger a heatwave. Recent news from The London Standard highlights that London is bracing for record-breaking June temperatures, with forecasts suggesting 30°C conditions, though current humidity at 88% and falling pressure may suppress this [6][9]. The resolution depends entirely on Wunderground publishing the highest temperature for all times on 30 June, so any delay in data publication could impact the settlement window ending 2026-06-30T12:00:00Z.

Sources: 1 · 2 · 3 · 4 · 5

Methodology

This page reviews Pronóstico: Highest temperature in London on June 30? across five venues. The live probability is the Polymarket mid-price, sourced directly from the on-chain Polygon order book; the comparison columns benchmark each venue on fee structure, KYC, settlement currency and payment rails. Every CTA routes to Polymarket Argentina, which mirrors the Polymarket order book at 0% fees.

Resolution & payout

At resolution the UMA oracle takes over: a proposer posts the outcome with a bond, any token holder can dispute within two hours. Without dispute the result is accepted and the smart contract distributes USDC instantly.

On Kalshi (CFTC-regulated) resolution runs through their in-house clearing engine in USD. Betfair Exchange settles after match end in the account's local currency. Manifold pays no cash — only its in-platform "mana" currency.

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.

How does resolution work?

Through the UMA Optimistic Oracle on Polygon: a proposer submits the outcome, a two-hour challenge window opens, and USDC payouts settle automatically once the result is final.

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.

What does Polymarket cost to trade?

Polymarket itself charges 0% — the only cost is the Polygon network fee, typically under $0.01 per transaction. Off-chain venues like Kalshi or Betfair charge 2-7% commission.

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.