The devastation caused by the recent heavy rains in Gujarat hardly needs introduction. In just 14 hours, several areas recorded rainfall exceeding 400 to 450 millimeters. Chikhli recorded 451 mm and Dholka recorded 440 mm of rainfall, leaving rivers, roads, and villages submerged. Until just a few months ago, international meteorologists had forecast that El Niño would bring drought conditions. However, in complete contrast to that prediction, floods wreaked havoc across Gujarat. The real force that suppressed the El Niño threat and drove this scale of extreme rainfall is the Pacific Decadal Oscillation (PDO).
PDO refers to long-term shifts in the surface temperatures of the Pacific Ocean. While El Niño (ENSO) shifts roughly once every 2 to 7 years, PDO persists in each phase for a far longer duration — approximately 20 to 30 years. PDO is currently in an extremely strong negative phase (with index values between -1.3 and -1.6). During this negative phase, the northeastern Pacific coastal waters turn cooler, while the central Pacific region becomes warmer.
When PDO is in its negative phase, the Indian summer monsoon strengthens to an unexpected degree. A monsoon trough forms that draws in large amounts of moisture from the western Pacific and the Indian Ocean, resulting in far higher-than-normal rainfall. This year, scientists focused heavily on the influence of El Niño. However, the negative PDO grew powerful enough to completely override the dry weather effect typically associated with El Niño, instead drawing continuous moisture-laden winds from the Arabian Sea toward Gujarat.
Extreme torrential downpours struck Vapi in southern Gujarat, dumping nearly nine inches of rain that engulfed cars and washed livestock away in surging currents. The sudden deluge has caused widespread flooding throughout several areas of Valsad district. pic.twitter.com/6GZYIMHRcj
— Gummalla Lakshmana (@GUMMALLALAKSHM3) July 23, 2026
There are two main reasons scientists were unable to accurately forecast the PDO’s effect. Weather prediction models primarily focus on El Niño, which operates over a timeframe of just a few months, and are not well-suited to capturing the decades-long complexity of PDO. In addition, rising global temperatures are altering ocean surface temperatures, intensifying PDO’s negative phase further — a shift that current weather models are not fully able to detect.
Due to their geography — proximity to mountainous terrain and coastal areas — districts like Navsari, Surat, and Valsad in Gujarat became particularly prone to heavy rainfall. This devastation occurred as the PDO’s influence pushed the monsoon trough further south. Going forward, weather forecasting must be built not just around El Niño, but around long-term oceanic systems such as PDO and the Indian Ocean Dipole (IOD) as well. If PDO continues in its negative phase, India may witness more such extraordinary heavy rainfall events and floods in the coming years.