Highest temperature in Helsinki on July 4?

Platform comparison

Market context

The underlying real-world event is the highest temperature recorded at Helsinki-Vantaa Airport on 4 July 2026, measured in degrees Celsius. Polymarket prices this contract today with the 18°C outcome at 86% probability, while the crowd-implied probability for a "YES" on any higher threshold sits at 0%, reflecting a market consensus that temperatures will not breach the 18°C mark. This pricing aligns with the Finnish Meteorological Institute’s 72-hour forecast, which predicts a daytime high of exactly 19°C with low model spread, yet the conditional tokens on the Polygon network currently discount that possibility significantly in favour of the lower range[1][3].

Historical context frames this low probability through July’s recent volatility, where a record-breaking heatwave saw temperatures exceed 30°C for 14 consecutive days, breaking the 1972 record and ending the month with sweltering conditions[2][8]. However, July 2026 began cooler than usual, and while the average high for Helsinki-Vantaa in July is 71°F (21.7°C), the current market pricing suggests a deviation from the seasonal norm towards the cooler end of the spectrum[4]. The 0% probability for higher outcomes mirrors the market’s caution despite the recent extreme heat, treating the current forecast as a distinct cooling episode rather than a continuation of the previous sweltering trend[2].

Traders should monitor the Finnish Meteorological Institute’s hourly updates and any sudden shifts in the 72-hour forecast model, as the low model spread currently points to 19°C but the market remains sceptical[3]. Key catalysts include the official release of the daily high temperature data from Wunderground, which will serve as the definitive resolution source, and any announcements regarding regional weather anomalies that could alter the temperature trajectory before the settlement window closes on 4 July 2026 at 12:00 UTC[1]. The on-chain mechanics using USDC and conditional tokens will resolve instantly once this data is confirmed, making the timing of the Wunderground update the critical dependency for position closure[1].

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 PolyGram, which mirrors the Polymarket order book directly.

Resolution & payout

Settlement runs on-chain. Polymarket's contract logic separates YES and NO shares as conditional tokens; at resolution the winning share lifts to $1.00 and the losing one to $0. The outcome input comes from the UMA Optimistic Oracle, which secures against bad resolution with a bond + dispute window.

Once finalised, the smart contract pays USDC to the holders' wallets within minutes — no withdrawal fees beyond Polygon network gas. Kalshi settles in USD via CFTC clearance, Betfair in account currency net of commission, Manifold in play-money mana with no cash-out.

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 PolyGram. 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'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.

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.