Monsoon Arrives Early in 2025, Sweeps Across Kerala to Maharashtra in a Day
Early Monsoon 2025: Rare Climatic Event Sweeps from Kerala to Maharashtra
India’s southwest monsoon arrived well ahead of schedule in 2025, marking a rare and expansive entry on May 24. In a dramatic shift from the usual staggered onset pattern, the monsoon swept simultaneously through Kerala, Tamil Nadu, Karnataka, and large parts of Maharashtra—signaling not just an early start, but also an unusually wide reach.
According to the Indian Meteorological Department (IMD), this early onset places 2025 among the rare years when the monsoon has surged in both intensity and breadth on its very first day—something not seen since 1971.
What Makes This Onset Unusual?
India’s monsoon onset typically unfolds over a few weeks, beginning in Kerala and gradually advancing northward. However, the 2025 season has defied convention:
- Early Onset: The monsoon arrived 7–10 days ahead of schedule across multiple states.
- Expansive Reach: Regions as far north as southern Maharashtra received monsoonal rain on Day 1.
- Rare Pattern: Such simultaneous advancement has occurred only a handful of times in India’s climate history—the last being over 50 years ago.
IMD reports confirm that active monsoon conditions are expected to persist until at least June 2, with rainfall expected to push deeper into eastern India before a temporary slowdown in early June.
Climatic Drivers Behind the Surge
Several interlinked climatic phenomena played a role in the early and forceful arrival of the 2025 southwest monsoon.
- Favourable Madden-Julian Oscillation (MJO)
The MJO, an equatorial disturbance that enhances tropical rainfall, entered a phase in mid-May that triggered strong convection over the Indian Ocean. By May 25, it further strengthened in Phase 4, accelerating the monsoon’s progression over southern India.
- Neutral El Niño–Southern Oscillation (ENSO)
El Niño typically weakens India’s monsoon, but this year, the ENSO is in a neutral phase—removing one of the major impediments to monsoon rainfall.
- High Atmospheric Moisture Content
Global warming has increased the atmosphere’s moisture-holding capacity by 6–8% per 1°C rise in temperature. With 2025 seeing global temperatures around 1.2°C above pre-industrial levels, the Arabian Sea and Bay of Bengal were primed with abundant moisture.
- Stronger Somali Jet
This low-level jet stream—key to transporting moisture from the equatorial Indian Ocean—was unusually strong this year, accelerating cloud formation and rain bands across India’s west coast.
- Low Himalayan Snow Cover
Between January and March 2025, Eurasian and Himalayan snow extent was 15% below the 30-year average. Reduced snow cover leads to increased land surface heating, which strengthens monsoon circulation.
Is Climate Change Behind This?
While the IMD remains cautious in directly attributing monsoon changes to climate change, experts point to emerging patterns that suggest otherwise. Rising sea surface temperatures, erratic snow cover, and increased moisture levels all align with climate-induced changes that affect large-scale monsoon systems.
India is already grappling with the consequences of changing monsoon behaviours—more frequent droughts, intense flooding, and shifting sowing seasons. This year’s early onset adds another dimension to the evolving narrative.
What Lies Ahead?
Forecast models predict that while the monsoon will remain active until early June, a brief lull may follow. This temporary slowdown is commonly linked to dry air intrusions from mid-latitudes, which can interrupt the moist monsoon flow.
Still, a strong beginning bodes well for agricultural sowing in early-season crops and replenishment of reservoirs. However, it also poses risks:
- Flash Floods: Unprepared regions could face sudden inundation.
- Urban Disruptions: Early rains can paralyze cities if infrastructure isn’t ready.
- Health Concerns: Stagnant water from early floods can trigger vector-borne diseases.
Outlook on Indian Ocean Dipole (IOD)
Though currently neutral, the IOD—another critical influencer of monsoon strength—is forecast to turn mildly positive by August. A positive IOD usually supports better rainfall across central and western India.