Louisiana’s low elevation and proximity to the warm, moisture-rich Gulf of Mexico make the state uniquely susceptible to extreme precipitation events. The constant inflow of tropical moisture, often channeled inland by slow-moving weather systems, leads to staggering rainfall totals over short periods. These intense downpours frequently overwhelm drainage systems and river basins, causing widespread, destructive flooding. Investigating the state’s meteorological history reveals the specific day that holds the official record for the greatest amount of rain to fall within a 24-hour period.
The Official Single-Day State Record
The highest officially recorded 24-hour rainfall total in Louisiana history occurred on August 28-29, 1962. The state record stands at 22.00 inches, measured at a gauge station within the Sabine National Wildlife Refuge. This refuge is located near the town of Hackberry, in the southwestern part of the state. The National Oceanic and Atmospheric Administration (NOAA) recognizes this 22-inch reading as the official single-day precipitation maximum. This measurement remains the benchmark for the state’s most intense single-day rainfall event.
The Storm System Responsible
The record 22.00 inches of rain was generated by a weak tropical disturbance that moved northward from the Gulf of Mexico. This system did not develop into a named tropical storm or hurricane, demonstrating that immense rainfall does not require a powerful, well-defined cyclone. The disturbance featured a massive pool of deep, tropical moisture that fed persistent, heavy thunderstorms over the southwestern coast. The primary mechanism for the extreme accumulation was the slow, almost stalled, movement of the low-pressure area. The system lingered, allowing continuous convergence of moisture into the same location for an extended period.
The atmosphere’s high precipitable water content meant that individual thunderstorm cells dropped torrential rain. As new cells developed and tracked over the Hackberry area, they repeatedly dropped incredible volumes of water, leading to the rapid 24-hour accumulation. This setup—a slow-moving, moisture-laden disturbance—is a common pattern for extreme rainfall events along the northern Gulf Coast.
Historical Context of Significant Rain Events
The 1962 record of 22.00 inches is an isolated peak that requires context when compared to other devastating rainfall events in Louisiana’s history. The state’s 48-hour rainfall record was set during the catastrophic 2016 Great Flood, often called the “no-name storm.” This event, which was not a tropical cyclone, dumped 31.39 inches over a two-day period in Watson, Louisiana, northeast of Baton Rouge. The 2016 flood’s multi-day total significantly surpassed the 1962 single-day total, illustrating the difference between an intense, localized 24-hour event and a widespread, prolonged deluge.
Another major comparison point is the impact of Hurricane Harvey in 2017. Although Harvey’s most extreme rainfall occurred in Texas, it produced a storm-total accumulation of 23.71 inches west of Vinton, Louisiana, near the Texas border. While the 1962 record is the official 24-hour maximum, the 2016 event demonstrated a greater geographic scope of extreme precipitation, with multiple parishes receiving over 20 inches across several days. Louisiana faces a dual threat: the historically intense, short-duration event like the 1962 record, and the multi-day, widespread rainfall events that lead to catastrophic flooding.