2017 North Indian Ocean cyclone season

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The 2017 North Indian Ocean cyclone season was below average but very deadly. It produced only three named storms, and only one of them grew into a very severe cyclonic storm. Most activity happened from April to December, with two peak periods in May and November. The India Meteorological Department (IMD) is the official forecaster for this basin, while the JTWC also issued advisories.

Key storms and events
- Maarutha (April 15–17): The season began with Maarutha in the Bay of Bengal. It reached cyclonic-storm strength and moved toward Myanmar, bringing heavy rain to parts of Sri Lanka and India, especially Andaman and Nicobar. Some damage and at least a few deaths were reported.
- Mora (May 28–31): Mora formed in the Bay of Bengal and reached a peak equivalent to a Category 1 hurricane on the global scale, then made landfall in southern Bangladesh near Chittagong. It caused dozens of deaths and widespread flooding in several countries, and its heavy rains helped start the early South Asian monsoon in some areas. Total damages were around $1.37 billion.
- Mid-year depressions and floods: A series of depressions and deep depressions formed over the Bay of Bengal and the Arabian Sea, bringing heavy rainfall and damaging floods across eastern and eastern-northern India (West Bengal, Jharkhand, Odisha), parts of Bangladesh, and neighboring regions. These events caused many fatalities and extensive damage, though they did not become powerful named storms.
- Ockhi (late November–December 9): The season’s strongest storm, Ockhi, formed in the southern part of the Bay of Bengal and then moved west-northwest, becoming a Very Severe Cyclonic Storm with peak winds around 155 km/h (100 mph). It caused severe damage across parts of India (notably Kerala and Tamil Nadu), Sri Lanka, and the Maldives region, and prompted large-scale evacuations. Heavy rains and rough seas also led to fatalities and destruction in multiple areas. Ockhi later weakened and dissipated off the coast of Gujarat by December 9.
- December system: Another low-pressure system formed in December and briefly reached tropical-storm strength before weakening and dissipating near the coasts of West Bengal and Bangladesh, bringing more heavy rain and flooding in the region.

Season impact
- Fatalities: About 834 people lost their lives across the affected countries.
- Damage: The season caused roughly $3.65 billion (2017 USD) in damage.
- Regions affected: While most storms stayed in the northern Indian Ocean, they affected many countries around the Bay of Bengal and the Arabian Sea, including India (especially Kerala, Tamil Nadu, Odisha, West Bengal), Bangladesh, Sri Lanka, Myanmar, and parts of Thailand and Indonesia due to heavy rains and floods.

Overview
The 2017 season was relatively quiet in terms of strong storms, with only one major cyclone reaching very severe intensity. Yet it was deadly because several depressions and floods caused widespread loss of life and property across the region. The IMD remained the official source for storm classifications in this basin.