Highest temperature in Toronto on May 25?

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Active sub-markets

Market context

Toronto's maximum temperature on 25 May 2026 will be recorded at Pearson International Airport, the official weather station for the region. The market currently shows 0% implied probability across all temperature bands, suggesting either a data loading issue or extreme uncertainty about which range will ultimately contain the day's high.

Historical May weather at Toronto Pearson reveals a median high of around 20°C, with typical daily maxima ranging from 16°C to 24°C depending on air mass positioning. The 30-year climate normal for late May sits near 22°C, though the station has recorded extremes from 11°C on cool, cloud-laden days to 29°C during early heat waves. The 0% crowd reading appears disconnected from this established baseline; even the coldest May 25ths on record exceed 10°C, and the warmest exceed 27°C. This suggests traders have not yet engaged with the market or are awaiting clearer resolution criteria confirmation.

The critical variable will be whether a high-pressure system dominates eastern Canada in late May 2026 or whether a frontal system brings cooler, unsettled conditions. Seasonal forecasts from Environment and Climate Change Canada, typically issued in April, will provide the first substantive signal about atmospheric patterns. Short-range guidance becomes reliable only in the final week before the date. Any early May heat dome affecting the eastern seaboard would shift expectations toward the 25–29°C bands, whilst a lingering spring pattern would favour 16–21°C outcomes. The settlement window closes at midday UTC, requiring Wunderground's historical data to be finalised by then.

Methodology

We track Highest temperature in Toronto on May 25? on the five venues with material liquidity for prediction markets. Live odds come from the Polymarket Polygon order book — the only source that ships real-time data under an open licence. For Kalshi, Betfair and Manifold we list platform attributes (fee, KYC, settlement, payment) instead of fabricated odds, because their APIs use non-comparable contract definitions.

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

Is this market available outside the US?

Who Will Win is available in most jurisdictions where Polymarket isn't directly accessible. Polymarket itself is geo-blocked in the US/UK/EU. Always check local regulations.

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.

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.

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.