Highest temperature in Chicago on August 9?

Platform comparison

Market context

Chicago’s temperature market is being priced around whether the city gets a routine late-summer high near the low-to-mid 80s or an outsized warm-up towards the upper 80s and beyond. The current crowd view is effectively locked on the 84–85°F band, while official normals put O’Hare’s August 9 average high at 83.3°F, so the market is leaning on a slightly above-normal outcome rather than a heat-wave breakaway.[1][2][11]

For context, Chicago’s August 9 record high is 97°F, set in 1913, but that is a long-tail benchmark rather than a baseline for forecasting.[11][13] Recent comparable cases suggest traders should read the probability as a function of modest summer warmth plus day-to-day cloud and shower risk, not as a bet on extremes: even a small reduction in solar heating can keep the realised high in the mid-80s, while a clear, dry afternoon is what would open the door to the upper 80s.[1][2]

The main catalyst to watch is the day-of forecast evolution from the National Weather Service and any late revisions to airport observations, since this contract resolves off the O’Hare daily observations table rather than the summary high-and-low display.[2][12] A recent local forecast setup pointed to near-normal conditions with only limited thunderstorm risk, which aligns with the market’s current preference for 84–85°F; if updated guidance shifts towards stronger sunshine or a delayed frontal passage, traders would expect the hotter bands to tighten, but the present signal remains a modestly warm, low-volatility setup.[1][5]

Sources: 1 · 2 · 3 · 4 · 5

Methodology

This page tracks Highest temperature in Chicago on August 9? across four political prediction venues. Live odds come from the Polymarket order book (the deepest political prediction-market book). Kalshi is the CFTC-regulated US alternative, Betfair the established UK sports-exchange with politics markets, Manifold the open play-money variant. For users geo-blocked from Polymarket directly, brokers like Trump Prediction provide a 0%-fee route into the same order book.

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.

Can prediction markets influence election outcomes?

Markets reflect expectations rather than create them. Studies show public-facing markets can anchor expectations, but don't influence the underlying outcome. Political markets are information, not advocacy.

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.

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.