Pronóstico: Highest temperature in London on June 30?

Platform comparison

Market context

The underlying real-world event is the highest temperature recorded at London City Airport on 30 June 2026, a date that historically sits at the start of London’s warm season with average highs above 67°F. Current crowd-implied probability for any outcome above 17°C is 0% YES, mirroring the Polymarket contract for 6 June 2026 where 17°C was priced at 100% under unsettled post-May conditions[1]. This suggests traders view early June as unlikely to breach 20°C without a sustained heatwave, despite today’s BBC forecast showing a high of 23°C and sunny intervals at the same airport[2].

Historical comparables frame this probability: the hottest June day ever in London reached 36.4°C at Heathrow on 30 June 2024, while a recent red extreme heat warning extended to 24 June 2026 saw temperatures hit 35.1°C in central London[6][9]. However, those were record-breaking anomalies, not typical early-June behaviour. The warm season officially begins 16 June, yet average daily highs only exceed 67°F from mid-June onward, making a 2026 breach of 20°C plausible but not probable without a catalyst[4].

Traders should watch the Met Office’s daily forecasts for London City Airport, which currently predict a maximum of 21°C with 66% cloud cover for 30 June[5], and the National Weather Service’s real-time data stream from EGLC, which shows temperatures hovering near 22°C at 4:50 am[3]. A key dependency is the resolution source, Wunderground, which will publish the first data point for 30 June only after 00:00 UTC, locking in the conditional token settlement on Polygon via USDC[1]. Any sudden shift in the southerly wind or pressure drop—currently falling at 1012mb—could signal an incoming heat spike, but no official announcement has yet triggered a probability reprice[2].

Sources: 1 · 2 · 3 · 4 · 5

Methodology

This page is a comparison snapshot: one live quote, four reference venues with their key attributes, and a single execution path — every trade button routes to Polymarket Qué Es, which mirrors the Polymarket order book directly.

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

Where can I trade this market with the lowest fees?

Polymarket is geo-blocked in the US/UK/EU. The easiest 0%-fee broker into the same order book is Polymarket Qué Es. Kalshi charges up to 7% per trade; Betfair Exchange takes 2-5% commission on net winnings.

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 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.

Do I need to KYC for this market?

On Polymarket directly, no — it's wallet-based. Intermediary brokers like Polymarket Qué Es 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.