A persistent heat dome has driven record October temperatures across Southern California, pushing downtown Los Angeles to 100°F or higher for five consecutive days through Tuesday, October 6—the longest such streak in the city’s records for any month. National Weather Service forecasts indicate highs near 97–98°F on Wednesday and 95–96°F on Thursday before a sharp cooldown to the low 90s Friday and mid-70s over the weekend, as the dome weakens and cooler air plus moisture from Hurricane Rachel’s remnants arrives. This rapid transition supports the market’s leading 56.1% implied probability for a five-day total streak while leaving room for the 41.2% chance of seven or more days if the high-pressure system lingers longer than current model consensus suggests. Historical rarity of multi-day 100°F October runs in Los Angeles further informs trader assessments of these thresholds.