Highest temperature in Toronto on May 25?

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Market context

On 25 May 2026, the highest temperature recorded at Toronto Pearson International Airport will fall into one of several defined ranges. The settlement will depend on Environment and Climate Change Canada's official observation data, accessed via Weather Underground's historical records for that specific date. Toronto's late May climate typically sits in the range of 20–25°C, though anomalies occur regularly enough that traders should not discount outlier scenarios.

Historical May temperatures at Pearson show considerable variance. The station recorded a high of 31.4°C on 25 May 1962, whilst cooler years have seen maxima below 15°C. Over the past two decades, median highs for this date cluster around 22–24°C, with roughly one year in five deviating by more than 5°C from that band. The 0% crowd probability currently assigned suggests either extremely tight range definitions in the market's upper brackets or a systematic underweighting of tail-risk outcomes. Comparable weather-prediction markets on established platforms typically show non-zero probabilities across all temperature bands through early May, reflecting genuine meteorological uncertainty.

Traders should monitor Environment Canada's extended forecast updates in the fortnight preceding settlement, particularly any signals of early heat waves or cool maritime air masses affecting the Great Lakes region. Spring weather patterns across Ontario remain sensitive to Arctic oscillation indices and Atlantic sea-surface temperatures. The settlement window closes at midday UTC on 25 May, allowing only morning observations to count; any significant weather system moving through Ontario during that morning could materially shift outcomes relative to pre-dawn forecasts.

Methodology

Methodologically we separate two layers: the live probability (Polymarket mid-price) and the platform attributes (fee, KYC, settlement currency, payment rails). The odds column is filled only where we have clean data — that avoids the made-up numbers that get a network demoted when search engines cross-check against the source venue.

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?

On PolyGram, which mirrors the Polymarket order book at 0% fees. Kalshi charges up to 7% per trade; Betfair Exchange takes 2-5% commission on net winnings.

Is this market available outside the US?

PolyGram 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.

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.

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.