Highest temperature in Toronto on July 16?

Platform comparison

Market context

Toronto Pearson International Airport recorded a peak of 34°C on 16 July 2026, marking the city’s first significant heat wave of the summer and confirming the 30°C range as the definitive outcome. This real-world event aligns with the market’s frontrunner, which currently assigns a 100% probability to the 30°C bracket, while the 27°C or below option sits at 0% [1]. Historically, mid-July highs in Toronto frequently breach 30°C during heat waves, with the 2026 event exceeding the 26°C threshold seen in the earlier July 7 prediction market, where traders priced that outcome at just 33.5% [3]. The current 0% implied probability for the lower range reflects this established pattern of summer extremes rather than an anomaly.

Programmatic traders should monitor Wunderground’s daily history feed for the CYYZ station as the primary settlement dependency, automating data pulls to verify the peak Celsius reading against the predefined ranges. While the settlement window closes on 16 July 2026 at noon UTC, the heat wave’s intensity was already flagged by Environment Canada, which advised at-risk populations to avoid strenuous outdoor activity and watch for heat exhaustion signs like dizziness and dark urine [2]. For conditional order strategies, the key catalyst is the official confirmation of the 34°C peak, which validates the 30°C range and eliminates ambiguity for algorithmic execution. Traders evaluating tooling should ensure their bots parse the gear icon temperature toggle on Wunderground to avoid Fahrenheit-to-Celsius conversion errors.

Sources: 1 · 2 · 3

Methodology

Methodologically we separate two layers: the live probability (Polymarket mid-price) and the platform attributes (fee, KYC, settlement currency, payment rails). That keeps the comparison honest — a single canonical probability across the row, with the venue-by-venue trade-offs spelt out in the columns next to it.

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

Where can I trade this market with the lowest fees?

Polymarket is geo-blocked in the US/UK/EU. The easiest 0%-fee broker into the same order book is Polymarket Review UK. Kalshi charges up to 7% per trade; Betfair Exchange takes 2-5% commission on net winnings.

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.