Highest temperature in Helsinki on July 4?

Platform comparison

Market context

The underlying event is the highest temperature recorded at Helsinki-Vantaa Airport on 4 July 2026, measured in degrees Celsius and resolved via Wunderground data. This single-day metric determines the market outcome, with settlement ending at 12:00 UTC on 4 July 2026.

Historical patterns show July is Finland’s hottest month, with average highs near 21°C (71°F) at Vantaa, though early July 2026 began cooler before a late-month heatwave pushed temperatures above 30°C in some areas[2]. Recent forecasts from the Finnish Meteorological Institute indicate a daytime high of 19°C for 4 July with low model spread, aligning with the current crowd-implied probability of 0% for higher ranges[3][5]. The 86% probability assigned to 18°C in parallel markets suggests traders view 19°C as the upper threshold, framing the current 0% YES probability as a conservative bet against exceeding that level[1].

Traders should monitor the 72-hour forecast updates from the Finnish Meteorological Institute, which currently project 19°C with tight confidence intervals[3]. Dependencies include real-time Wunderground readings and wind direction shifts, as the current NE flow at 12 mph may limit heat accumulation[4]. A recent BBC Weather update confirms today’s observed temperature at 16°C, reinforcing the trend toward moderate highs rather than extreme values[4]. No official announcements are expected, but sudden changes in cloud cover or pressure (currently falling at 1012mb) could alter the outcome[4]. Programmatic approaches would track Wunderground’s hourly data feed and cross-reference with Met Office gust limits, which cap at 18°C for maximum feels-like temperature[9].

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 Kalshi Fees, 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 Kalshi Fees. Kalshi charges up to 7% per trade; Betfair Exchange takes 2-5% commission on net winnings.

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.

Do I need to KYC for this market?

On Polymarket directly, no — it's wallet-based. Intermediary brokers like Kalshi Fees trigger KYC only above $1,500 of lifetime trading volume; under that you trade pseudonymously with a single wallet address.