Highest temperature in Helsinki on July 4?

Platform comparison

Market context

The real-world event hinges on the highest temperature recorded at Helsinki-Vantaa Airport on 4 July 2026, measured in degrees Celsius and resolved via Wunderground data. Historically, July is the warmest month in Helsinki, with daytime highs averaging around 21°C and overnight lows near 15°C[3]. While recent years saw a record-breaking heatwave ending July with temperatures exceeding 30°C, the current 72-hour forecast predicts a daytime high of just 19°C with low model spread, suggesting cooler-than-average conditions for this specific date[1][2]. This historical context explains why the crowd-implied probability for hitting 19°C is currently 0% YES; the market is pricing in a significant deviation from the typical July warmth.

Traders approaching this market programmatically should monitor real-time Wunderground feeds and cross-reference with the Finnish Meteorological Institute’s hourly updates, as sudden shifts in wind direction or cloud cover could alter the peak temperature. A key catalyst is the NE wind forecast for 4 July, which typically brings cooler air compared to the SE winds seen on 3 July[4]. Additionally, the UV index remains moderate, and while thunderstorms are unlikely, any unexpected rain event could suppress temperatures further[3]. Recent forecasts from AccuWeather indicate daily highs ranging from 65°F to 74°F (18°C–23°C) for July 2026, but the specific 19°C target remains uncertain given the current cool start to the month[6]. Power-users should deploy conditional orders tied to Wunderground’s live temperature stream to capitalise on intraday volatility.

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 Polymarket Review UK, which mirrors the Polymarket order book directly.

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

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 Polymarket Review UK. 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 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 Polymarket Review UK trigger KYC only above $1,500 of lifetime trading volume; under that you trade pseudonymously with a single wallet address.