Highest temperature in London on August 2?

Platform comparison

Market context

The event is the **highest temperature recorded at London City Airport** during the day, with settlement based on the Wunderground daily history page for that station. In practical terms, the market is a tight intraday weather print rather than a broad London average, so a small shift in cloud cover, sea breeze or the timing of sun can move the outcome by a degree or two.

The current 0% YES reading looks detached from the weather setup implied by forecast material already circulating, which points to a mid-to-high 20s Celsius day rather than an extreme outlier. Polymarket’s own market page shows the crowd clustered around **27°C** with **26°C** and **28°C** also meaningful, while Met Office-based commentary there describes strengthening high pressure, light winds and southerly flow as supportive of a daytime maximum around 27°C[1]. London has also already produced a 26.6°C high at Kew Gardens earlier in 2026, which frames this as a potentially warm but not exceptional summer reading[4][18].

For traders, the main catalysts are the final local forecast updates, the first post-noon observations, and whether the station’s daily high is revised before the next day’s first datapoint appears, since the market rules allow revisions within that window[1]. On the crypto side, the contract settles in USDC on-chain, so the price will mainly reflect local weather information rather than BTC or ETH direction, although broader risk appetite can still affect liquidity, spreads and short-term order flow. If the wider market is risk-on, that can support tighter books and faster repricing when late forecast changes land; if not, the crowd can stay anchored near a single probabilistic band even when weather uncertainty remains.

Sources: 1 · 2 · 3 · 4 · 5

Methodology

Methodologically this overview focuses on on-chain pricing: Polymarket's live mid comes from the Polygon conditional-token order book and settles automatically in USDC. The other three venues — Kalshi, Betfair, Manifold — sit alongside as off-chain reference points so you can see how the contract translates across regulatory and settlement regimes.

Resolution & payout

Settlement is on-chain via UMA Optimistic Oracle. A proposer posts the outcome with a bond, a two-hour dispute window opens, then the smart contract lifts winning conditional tokens to 1 USDC and sends payments to holders' wallets automatically. No withdrawal fees beyond Polygon gas.

Off-chain venues (Kalshi, Betfair, Smarkets) settle in local fiat through bank-side clearing — faster than SWIFT, slower than on-chain. Manifold pays no real cash.

FAQ

Why USDC and not ETH or USDT?

USDC is the Polygon standard — audited reserves (Circle, monthly attestation), deepest order book, low gas costs. ETH volatility would distort probability quotes; USDT has thinner Polygon liquidity than USDC.

What does a transaction cost on Polygon?

Polygon gas is typically under $0.01 per transaction. A full trade cycle (Approve + Order + Fill) totals around $0.03 — compared to $5-50 on Ethereum mainnet.

Can I use Bitcoin directly?

No, Polymarket operates exclusively in USDC on Polygon. You can bridge BTC to USDC via an exchange or bridge service and deposit on Polygon — typically 10-30 minutes processing time.

How volatile are crypto prediction markets?

Crypto markets react to spot prices — a 5% BTC move typically shifts a "BTC above X by date" market 10-20%. Polymarket crypto market liquidity is usually six-figure USD, sufficient for active trading.

Which crypto markets exist on Polymarket?

Currently active markets include BTC/ETH/SOL price targets, halving dates, ETF approvals, hard-fork outcomes and Layer-2 TVL thresholds. The list updates weekly; biggest volume sits on BTC and ETH price forecasts.