Atlanta Weather Arb Offers 9423% Spread as Kalshi and Polymarket Dislocate

A massive pricing dislocation has opened up across municipal weather contracts. The cleanest play is Atlanta's June 5 maximum temperature. On Polymarket, the 84-85°F 'NO' contract is trading at 0.1¢ (implying a 99.9% probability of 'YES'), while on Kalshi, the 'YES' contract for the exact same bracket is priced at just 1.0¢. This mismatch yields a theoretical 9423.81% net return ($47,119 profit on a $500 risk-balanced layout). However, execution requires navigating a critical structural detail: Polymarket's contract expired on June 5, whereas Kalshi's settlement is slated for June 12. This creates a settlement lag. Furthermore, watch out for bracket mismatches on other pairs. Dallas, Houston, and Los Angeles show identical nominal pricing gaps, but the listed brackets do not align (e.g., Dallas Poly 82-83°F vs Kalshi 84-85°F). Do not blind-buy these mismatching brackets expecting a clean arb; they are distinct directional legs. For the Atlanta arb, Kalshi order book depth is thin at $22,328 volume, while Polymarket has deeper liquidity ($62,821). For size, the Los Angeles contract offers the deepest Kalshi pool ($91,503) but carries a wide bracket gap (64-65°F vs 69-70°F). Execute via limit orders only; slippage at sub-penny levels will instantly destroy your edge.