Factors Behind Monsoon’s Early Nationwide Arrival in 2025

Early Monsoon 2025

Early Monsoon 2025 Latest News

  • The southwest monsoon covered the entire country by June 29, nine days earlier than its usual date of July 8. 
  • This is only the tenth time since 1960 that the monsoon achieved nationwide coverage in June.

Early Onset in Kerala Set the Pace

  • The monsoon arrived in Kerala on May 24, eight days earlier than usual, driven by an active Madden-Julian Oscillation (MJO) phase in mid-May. 
  • This early onset laid the foundation for the monsoon’s rapid progress.
  • Monsoon Progress: Mostly Ahead of Schedule
    • South, East, and Northeast India saw early arrival.
    • Northwest India was near normal.
    • Central India witnessed slight delays.
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Key Drivers of the Monsoon’s Rapid Advance

  • The southwest monsoon covered the entire country by June 29, nine days ahead of its normal schedule of July 8. 
  • This marks only the tenth instance since 1960 that nationwide monsoon coverage occurred in June.

Low Pressure Systems

  • India experienced five low-pressure systems in June. 
  • These act as moisture magnets, drawing in rain-bearing winds and accelerating monsoon movement inland.

Active Madden-Julian Oscillation (MJO)

  • MJO is a moving system of clouds, rainfall, winds, and pressure near the equator that travels eastward. 
  • When active near India, it enhances monsoon by increasing cloud cover and moisture, leading to stronger rainfall. 
  • An active MJO phase significantly boosts monsoon onset and progression.
  • June continued to see an active MJO, enhancing cloud formation and pushing rainfall northwards, aiding monsoon spread.

Favourable Monsoon Trough Position

  • The monsoon trough is an elongated low-pressure area extending from northwest India to the Bay of Bengal. 
  • It plays a key role in determining rainfall distribution during the monsoon. 
  • A favourable monsoon trough position, especially when it shifts south of its normal, helps draw in moisture-laden winds from the oceans, intensifying rainfall over central and northern India. 
  • Its position influences the strength, spread, and duration of monsoon rains.
  • The monsoon trough remained south of its normal position, facilitating increased moisture inflow and early rainfall across regions.

Neutral ENSO (El Niño-Southern Oscillation) Condition

  • ENSO is a climate pattern involving temperature fluctuations in the central and eastern tropical Pacific Ocean, with three phases: El Niño, La Niña, and Neutral.
  • A neutral ENSO phase means sea surface temperatures are close to average. 
  • This phase neither suppresses nor excessively enhances rainfall, allowing the Indian monsoon to progress normally, supporting stable and widespread rainfall patterns.
  • ENSO was in a neutral phase, supporting normal monsoon rainfall.

Neutral IOD (Indian Ocean Dipole) Conditions

  • An is a climate phenomenon marked by differences in sea surface temperatures between the western and eastern Indian Ocean. 
  • It has positive, negative, and neutral phases.
  • A neutral IOD phase means there is little to no temperature difference between the two regions, resulting in minimal influence on the Indian monsoon. 
  • This allows monsoon rainfall to be primarily driven by other favorable factors like MJO and ENSO.
  • This year, IOD also remained neutral, having minimal impact—neither enhancing nor suppressing rains.

Conclusion

  • This year’s monsoon has been marked by early onset, rapid progression, sudden pauses, and localised weather disasters. 
  • With much of the season still ahead, it remains uncertain whether the pattern will stabilise or intensify further.

Source: IE | DTE | IE

Early Monsoon 2025 FAQs

Q1: What caused early monsoon in 2025?

Ans: Active MJO, multiple low-pressure systems, and favorable monsoon trough helped the monsoon advance rapidly across India.

Q2: What is the role of MJO in monsoon?

Ans: MJO brings increased moisture and cloud cover, enhancing monsoon strength and rainfall across India during its active phase.

Q3: How does ENSO affect Indian monsoon?

Ans: Neutral ENSO conditions help maintain stable rainfall, unlike El Niño, which suppresses monsoon activity across India.

Q4: Why is monsoon trough important?

Ans: Its southward position helps pull moisture-laden winds inland, boosting rainfall in central and northern India.

Q5: Did IOD play a role in the 2025 monsoon?

Ans: IOD remained neutral, having minimal influence, allowing MJO and low-pressure systems to dominate monsoon dynamics.

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