Highest temperature in Toronto on May 25?

Platform comparison

Active sub-markets

Market context

Toronto's weather on 25 May 2026 will produce a single daily high temperature, recorded at Pearson International Airport's official meteorological station. This value—measured in degrees Celsius and settled via Wunderground's historical data—determines which temperature band the market resolves to. The settlement window closes at midday UTC on that date, meaning traders must account for any final temperature adjustments before the official record closes.

May in Toronto typically sees highs between 18–24°C, though the range widens considerably depending on air mass positioning. Historical May 25th data shows variability: the station recorded 28.3°C in 2022, 19.4°C in 2019, and 15.6°C in 2018. This 12–13°C spread across recent years reflects the transitional nature of late spring in southern Ontario, where Arctic outbreaks can still occur alongside early summer warmth. Traders evaluating probability distributions should weight the frequency of moderate outcomes (20–23°C) against tail scenarios, which remain plausible but less common.

Programmatic traders monitoring this market should integrate Environment and Climate Change Canada's seasonal forecasts, typically released 10–14 days prior, alongside real-time upper-air pattern data from the GFS and HRRR models. The North Atlantic Oscillation and jet stream positioning in late May 2025 will signal whether high-pressure systems dominate (pushing temperatures toward 25°C+) or whether cooler troughs persist. Wunderground's historical archive allows backtesting settlement logic against prior May 25th records, enabling conditional order placement once spring 2026 pattern confidence solidifies.

Methodology

This page is a comparison snapshot: one live quote (Polymarket), 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

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 it cost to trade on PolyGram?

Zero. PolyGram routes every order to the live Polymarket order book; the only cost is the Polygon network fee, typically under $0.01 per transaction.

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?

Not under $1,500 of lifetime trading volume. Above that threshold, PolyGram triggers a quick verification flow that finishes in minutes.