Highest temperature in Los Angeles on July 17?

Platform comparison

Market context

Los Angeles recorded its peak heat for 17 July 2026 at the Los Angeles International Airport Station, with the official figure settling within a specific Fahrenheit range. While one prediction market shows a 0% implied probability for a “YES” outcome on a particular range, Polymarket’s active contract for the same event identifies 80–81°F as the frontrunner at 75%, with 78–79°F trailing at 12%[1]. This stark divergence between platforms highlights a critical cross-venue arbitrage opportunity, where the zero-probability line likely reflects a mispriced or illiquid contract rather than a genuine consensus on the weather outcome.

Historical mid-July data for Los Angeles typically sees highs clustering between 75°F and 85°F, making the 80–81°F range a statistically probable outcome consistent with seasonal norms. The market’s successful prediction of a 74–75°F peak on 4 July 2026 suggests the underlying models are calibrated to local microclimates, reinforcing the credibility of the 75% probability assigned to the 80–81°F range over the null position[2]. Traders should view the 0% line as an outlier inconsistent with both historical precedent and the active pricing on competing exchanges.

Key catalysts for this contract remain static, as the settlement relies solely on the Wunderground daily record for KLAX, removing the need for real-time news monitoring. The resolution source is fixed at the highest temperature recorded for all times on 17 July at the airport station, accessible via the official Wunderground history page[1]. With the settlement window closing on 17 July 2026 at 12:00 UTC, the only variable is the final data upload, meaning the current pricing discrepancy between platforms is the primary factor for decision-making rather than external announcements.

Sources: 1 · 2

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

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

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 Polymarket cost to trade?

Polymarket itself charges 0% — the only cost is the Polygon network fee, typically under $0.01 per transaction. Off-chain venues like Kalshi or Betfair charge 2-7% commission.

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?

On Polymarket directly, no — it's wallet-based. Intermediary brokers like Best Prediction Markets UK trigger KYC only above $1,500 of lifetime trading volume; under that you trade pseudonymously with a single wallet address.

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.