Highest temperature in Los Angeles on August 9?

Platform comparison

Market context

The relevant event is the maximum temperature logged at Los Angeles International Airport on 9 August, and the contract now sits with the **80–81°F** bin carrying about **99%** implied probability, while other bins are effectively priced out. That is broadly consistent with the official Weather Underground-linked outcome definition and with nearby public weather references showing a cooler coastal Los Angeles pattern than the hotter inland parts of the basin.[2][10][12]

Historically, LAX daily highs in August often cluster in the upper 70s to mid-80s, so a realised peak in the low 80s is ordinary rather than exceptional. Recent local coverage has also highlighted that August heat can produce record readings across Los Angeles-area stations, but those inland spikes do not necessarily translate to the airport, which is typically moderated by marine influence; that gap helps explain why traders have heavily favoured a narrow range here.[15][17] The main cross-platform divergence is not between major venue pricing and analyst view, but between this contract’s near-certainty and the broader public sense of Los Angeles “heat”, which is often informed by inland conditions rather than LAX itself.[4][5]

For traders, the key dependency is the final Weather Underground Daily Observations entry for LAX and whether any late revision appears before the next day’s first datapoint, since the market rules make that table the primary source.[2] In practice, that means the decisive catalyst is the overnight data publication cycle rather than a new forecast headline, though NWS airport observations and local forecast products remain useful for checking whether a late-afternoon surge could have nudged the day’s maximum above the currently expected bin.[10][13][14]

Sources: 1 · 2 · 3 · 4 · 5

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

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?

Polymarket itself is geo-blocked in the US/UK/EU. Always check the legal status of prediction markets in your jurisdiction before trading.

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.

Do I need to KYC for this market?

On Polymarket directly, no — it's wallet-based. Intermediary brokers like PolyGram 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.