Highest temperature in Toronto on May 25?

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Market context

On 25 May 2026, Toronto Pearson International Airport will record a daily high temperature, measured in Celsius. The market currently prices at 0% YES, indicating traders expect the eventual reading to fall outside whichever temperature band this contract covers—a reflection of genuine uncertainty about spring weather in the Greater Toronto Area. Settlement hinges on Wunderground's historical data feed for that specific station, with the window closing at noon UTC on the day itself.

Toronto's late May climate sits at a transitional point. Historical records from Environment Canada show daily highs in late May typically range between 20–24°C, though outliers occur; the station has recorded highs as low as 12°C and as high as 31°C in this window across different years. The 0% pricing suggests the market may be anchored to an extreme or narrow band—traders should verify the exact temperature thresholds this contract settles against, as a seemingly "normal" May day could resolve YES or NO depending on those boundaries.

Weather forecasting accuracy degrades sharply beyond ten days, making pre-May catalysts limited. The relevant driver is atmospheric setup in late May itself: ridge positioning over eastern North America, lake-effect modulation from the Great Lakes, and any lingering spring systems. Traders monitoring seasonal outlooks from Environment and Climate Change Canada in early May, or watching for anomalous warmth patterns in mid-May forecasts, will have clearer signal than current positioning allows. The settlement source's reliance on a single airport station also means local conditions matter—any equipment issues or data gaps would affect resolution.

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

Polymarket-based markets settle through the UMA Optimistic Oracle on Polygon. A proposer submits the outcome, a two-hour challenge window opens, and unchallenged proposals finalise the resolution. Payouts settle automatically in USDC the moment the result is final — no bookmaker, no delay.

Kalshi-based markets settle in USD via the CFTC-regulated clearinghouse. Betfair Exchange settles in GBP/EUR net of commission. Manifold is play-money and does not pay out real funds.

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 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.

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.