Kīlauea’s ongoing Halemaʻumaʻu summit eruption follows a well-documented pattern of episodic lava fountaining driven by cyclic inflation and deflation recorded in tiltmeter data from the USGS Hawaiian Volcano Observatory. Trader consensus at 96% for an August 11–12 start reflected narrowing forecasts from precursory overflows and spatter at the north vent, combined with typical recharge intervals between episodes that placed the window squarely in that period. Official monitoring confirmed fountaining began at 3:45 p.m. HST on August 12 after sustained lava flows transitioned to sustained activity. This outcome could have been delayed by slower pressure buildup or vent blockage, though real-time geophysical signals made such shifts unlikely once deflationary tilt accelerated.