Countdown Starts For Seasonal Monsoon Rainfall: Monsoon Misses The Normal Onset Date
Key Takeaways:
- The Southwest Monsoon missed its normal onset date of June 1 over Kerala.
- Despite an early arrival over the Andaman Sea, the monsoon advance has slowed considerably.
- Weak monsoon winds and poorly aligned cloud structures are delaying mainland entry.
- Even after onset, the monsoon may struggle to advance smoothly across Peninsular India.
The Southwest Monsoon missed its normal onset date of 01 June over Kerala. Earlier, the monsoon stream had arrived ahead of schedule over the Andaman Sea and South Sri Lanka on 16 May 2026. However, its further advance has remained sluggish. Against the normal travel time of about a week to reach Kerala, the monsoon current is still struggling to push over mainland India. A weak monsoon current is lingering on the outskirts, covering the Maldives and Comorin region, and is waiting in the wings to spread across Sri Lanka and extreme South Peninsular India.
Notwithstanding the arrival date, the countdown of seasonal rainfall has commenced with effect from today. In fact, the recorded rainfall of the past 24 hours till 8:30 a.m. this morning will be counted against 01 June 2026. The seasonal rainfall count continues till 30 September, even if monsoon rains linger beyond this date over some parts of the country.
Over the last ten years, the monsoon has witnessed a mix of early arrivals and delayed onsets. The monsoon arrived as early as 24 May last year and overshot the normal onset date by about a week in 2016, 2019 and 2023, reaching Kerala on 08 June in those years. By and large, the onset has remained within the standard deviation of about one week, which is considered a fairly consistent record.
For the onset of monsoon, in addition to widespread stratified rainfall, clouds and winds also need to align properly. Monsoon winds form a stable stream, and the associated cloud mass has a distinct structure. However, the present cloud cluster over the Southeast Arabian Sea, Comorin and Maldives region lacks the characteristics of typical monsoon clouds.
Though there are indications of the monsoon reaching mainland India within the next 3–4 days, it may have to compromise with the conventional onset parameters. Even if the monsoon stream advances over the mainland during this period, it may struggle to maintain the pace and rhythm required to cover the interiors of Peninsular India smoothly.
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