Highest temperature in Toronto on May 25?

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Market context

Toronto's weather on 25 May 2026 will be measured at Pearson International Airport, with the settlement hinging on the single highest temperature recorded that day in Celsius. The resolution uses historical data from Weather Underground, capturing the peak reading across all daylight and evening hours at the station in Mississauga.

May temperatures in Toronto typically range from 15°C to 22°C, though the historical record for the month reaches 31.1°C, set in 1962. Recent Mays have shown considerable variation; the median high sits around 20°C, but outlier warm days do occur roughly once per decade. The current 0% crowd probability suggests traders are pricing in either an expectation of moderate spring conditions or uncertainty about which temperature bracket will ultimately resolve. Historical frequency data indicates days exceeding 25°C in late May occur in fewer than 20% of years, whilst readings above 28°C are genuinely rare for this date.

Traders monitoring this market should track Environment Canada's seasonal forecasts released in April 2026, which typically provide confidence intervals for May temperature patterns. Upper-air patterns in late spring—particularly the position of the jet stream and any early heat domes pushing north from the continental interior—will be decisive. Anomalously warm air masses occasionally reach southern Ontario by late May, though such events remain statistically infrequent. The settlement window closes at midday on 25 May, meaning the final reading will exclude any evening temperature decline.

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

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.

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.

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.