Highest temperature in Amsterdam on August 17?

Platform comparison

Market context

The crowd is pricing zero probability that Amsterdam Airport Schiphol will record a temperature of 40°C or higher on 17 August 2026. This represents an extreme weather event for the Netherlands, where August temperatures typically peak in the mid-20s Celsius. The settlement hinges on the Daily Observations table at Weather Underground rather than summary figures, which may introduce minor variance depending on measurement timing and station calibration.

Historical precedent suggests the 0% pricing reflects genuine rarity. Amsterdam has never recorded 40°C in its instrumental record spanning over 150 years. The all-time Dutch high stands at 40.7°C, set in July 2022 during an exceptional heatwave. August temperatures in Amsterdam have peaked around 30–31°C in recent decades, with sustained heat above 35°C extremely uncommon. The last time the city approached 35°C in August was 2003, during Europe's catastrophic summer heatwave. Current climate models do not project a shift in August baseline temperatures sufficient to make 40°C plausible within a single-day event.

Traders monitoring this market should track European summer weather patterns from June onwards, particularly any signals of an unprecedented Atlantic blocking pattern or heat dome formation. The Dutch meteorological institute (KNMI) will issue seasonal forecasts in July that could shift expectations if anomalies emerge. However, the physical constraints of Amsterdam's maritime climate—proximity to the North Sea moderates extremes—make the 40°C threshold structurally unlikely. Any movement in this market would require forecasters to signal a once-in-centuries weather system, which remains absent from current seasonal outlooks.

Methodology

Methodologically we separate two layers: the live probability (Polymarket mid-price) and the platform attributes (fee, KYC, settlement currency, payment rails). That keeps the comparison honest — a single canonical probability across the row, with the venue-by-venue trade-offs spelt out in the columns next to it.

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

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.

Do I need to KYC for this market?

On Polymarket directly, no — it's wallet-based. Intermediary brokers like Who Will Win 2026 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.