Highest temperature in London on June 1?

Platform comparison

Active sub-markets

Market context

On 1 June 2026, the highest temperature recorded at London City Airport will settle into one of several defined ranges. The market uses Wunderground's historical data feed as the single source of truth, with settlement occurring at midday UTC. Across major prediction platforms, this market shows material divergence in how liquidity clusters: Polymarket's order-book model typically concentrates volume in the most probable bands, whilst Kalshi's binary structure forces traders into tighter yes/no positions on specific thresholds. Betfair's decimal-odds interface and Smarkets' fractional pricing both allow finer granularity, though their KYC requirements and regional restrictions differ from Polymarket's approach.

London's June temperatures have historically ranged from 13°C to 28°C, with the median high around 20–22°C. The 0% crowd probability currently assigned suggests either extreme confidence in a baseline scenario or insufficient trading activity to establish a floor. Comparable June days in 2015 and 2019 saw highs of 25°C and 26°C respectively, providing calibration points for assessing whether the current odds reflect genuine weather forecasting or liquidity constraints.

Traders should monitor the UK Met Office's long-range forecast updates in late May, which typically refine seasonal patterns into week-specific predictions. Atlantic pressure systems and jet-stream positioning in early June will be the primary drivers; any early-summer heatwave signals from continental Europe could shift expectations upward. Fee structures matter here—Polymarket's 2% maker/taker model differs from Kalshi's fixed spreads, potentially affecting whether small temperature-band trades remain economically viable through settlement.

Methodology

We read Highest temperature in London on June 1? from four platform perspectives: Polymarket (on-chain CLOB), Kalshi (CFTC-regulated exchange), Betfair Exchange (sports book exchange), Smarkets (peer-to-peer betting exchange). Polymarket's live quote comes directly from the Polygon order book; the other three are listed with their platform attributes — fees, KYC, settlement currency, payment options — because a 1:1 contract comparison without API access would be guesswork.

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

Where can I trade this market with the lowest fees?

On Polymarket Alternative, which mirrors the Polymarket order book at 0% fees. Kalshi charges up to 7% per trade; Betfair Exchange takes 2-5% commission on net winnings.

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 does it cost to trade on Polymarket Alternative?

Zero. Polymarket Alternative routes every order to the live Polymarket order book; the only cost is the Polygon network fee, typically under $0.01 per transaction.

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.

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.