Highest temperature in Paris on August 9?

Platform comparison

Market context

The relevant event is whether Paris–Le Bourget Airport’s highest recorded temperature, measured from the Weather Underground **Daily Observations** table, lands in a given Celsius band by the settlement cutoff. Forecasts around the date point to a warm start: Time and Date shows Paris near 90°F/63°F with showers late and cloudier conditions, while local forecast coverage says the weekend of 8–9 August could still reach or exceed 30°C.[9][13]

The current **1% YES** price implies the market is heavily leaning towards a lower outcome band than a hot-weather spike. That is consistent with the wider August climatology for Paris, where average daytime highs are far below early-August heatwave levels, even though recent French summers have shown that brief extremes can still push readings sharply higher; Reuters reported in June that French weather officials were already seeing temperatures at record or near-record levels during the 2026 heatwave sequence.[12][19] For comparison, when traders have priced similar temperature contracts, the market often concentrates quickly into the most likely single band once short-range forecasts narrow, as seen in the Polymarket Paris temperature market for 8 August where one outcome reached 100%.[11]

For traders, the main catalysts are the latest station observations through the settlement window and any late forecast revisions from the forecast models that affect Paris–Le Bourget’s afternoon maximum. Because the contract settles on the Weather Underground **Daily Observations** table rather than the summary high/low, intraday updates matter more than headline weather app displays; a brief late-afternoon surge would be enough to move the outcome band even if the day looked milder earlier. In crypto terms, USDC settlement removes fiat friction, so price changes are likely to track information flow rather than payment mechanics, while broader BTC/ETH volatility may still influence risk appetite at the margins if macro moves trigger rotation into or out of event-driven markets.

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.

UK Frequently Asked Questions

What are crypto prediction markets?

Crypto prediction markets are on-chain smart contracts where you buy YES or NO shares on a future crypto event (e.g. "BTC above $100k by year-end"). The market price between 0¢ and 100¢ is the implied probability.

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.

Is Polymarket legal in the UK?

Polymarket is accessible to UK traders but is not UKGC-licensed. It operates under US CFTC jurisdiction. UK residents face no domestic legal prohibition on using it, but UKGC consumer protections do not apply. For UKGC-regulated alternatives, Betfair Exchange and Smarkets offer similar prediction-style markets.

Do I pay tax on prediction market profits in the UK?

UKGC-licensed platform profits (Betfair, Smarkets) are typically tax-free gambling winnings for UK individuals. Polymarket profits involve USDC crypto transactions, which HMRC treats as Capital Gains Tax events. Keep full transaction records and report via Self Assessment if gains exceed £3,000 per tax year.

How do I deposit on Polymarket from the UK?

UK traders typically fund Polymarket via Coinbase UK, Kraken or Revolut — buying USDC with GBP and transferring to a Polygon-compatible wallet (MetaMask, Coinbase Wallet). Polymarket's onboarding walks you through the bridging process. Typical GBP-to-USDC conversion costs 0.5–1%.