Highest temperature in Seattle on August 9?

Platform comparison

Market context

Seattle’s August heat is usually modest, with the long-run climate normal for Sea-Tac sitting around the high 70s Fahrenheit rather than the 80s or 90s, so markets on a single-day high generally hinge on whether a brief warm spell arrives or coastal influence keeps the afternoon down. Recent comparable readings point to that pattern: Weather Underground’s Sea-Tac daily-observation rule means the eventual settlement will depend on the highest in-day reading, not the headline daily high, and the market has already been priced as a near-lock around the mid-to-upper 70s after the observed outcome came in close to seasonal norms.[1][8]

For context, Seattle’s August highs often cluster in the mid-70s to low 80s, but the city can still spike when inland heat or a stronger ridge builds over western Washington. That is why the current crowd signal is better read as a weather-resolution market than a true uncertainty event: it is leaning on climatology and the likely absence of a major heat surge, similar to past late-summer Seattle days that settled near normal rather than breaking out into extreme heat.[2][8][13]

The main catalyst traders would have watched was the late-week forecast evolution from the National Weather Service and other forecasters, especially any shift in offshore flow, marine layer depth, or high-pressure strength before the observation window closed. In practice, the decisive inputs were the short-range model trends and the actual Sea-Tac station observations, with Weather Underground’s daily observations as the settlement source if there was any discrepancy with summary figures.[1][6]

Sources: 1 · 2 · 3 · 4 · 5

Methodology

Political prediction markets differ structurally from sports betting: thinner liquidity, longer settlement windows, higher sensitivity to single news events. This page shows the live Polymarket quote for Highest temperature in Seattle on August 9? plus platform attributes for the three reference venues, so you can see at a glance where the deepest market for this question sits.

Resolution & payout

Political markets typically settle on official candidate or agency confirmation. Polymarket uses UMA Optimistic Oracle: a proposer posts the outcome with a bond, the two-hour window opens, then the smart contract pays USDC.

Kalshi settles USD via CFTC clearinghouse, with clearly defined resolution sources (e.g. AP race calls for elections). Betfair settles after the official outcome is registered with the league or agency. Manifold is play-money.

UK Frequently Asked Questions

How accurate are political prediction markets?

Historically more accurate than polls. Polymarket's Brier score on US 2024 elections was ~0.11 — better than 538 (~0.14) and every mainstream poll. Markets aggregate information with real skin in the game.

What resolution source is used for elections?

Polymarket defines the source per contract — usually Associated Press (AP Race Call), Reuters or the official electoral commission. The source is stated in contract details before the market opens.

Which platform has the deepest political liquidity?

Polymarket — by far. US 2024 presidential volume was ~$3.5B vs Kalshi (~$200M) and Betfair (~$120M). Where Polymarket is geo-blocked, brokers like Trump Prediction route into the same order book at 0% fees.

How fast do political markets react to news?

High-liquidity markets move within seconds to minutes. A Trump tweet on the economy can shift the "Trump 2024" market 2-5 points before mainstream media has written anything.

Are UK election prediction markets available from the UK?

Yes. Betfair Exchange and Smarkets offer UKGC-regulated UK election markets (seat counts, party share, constituency results). Polymarket also lists UK election contracts with deeper global liquidity. Betfair winnings are typically tax-free for UK individuals; Polymarket profits are subject to HMRC CGT.