The 2025 North Indian Ocean cyclone season was the costliest season on record and the deadliest since 2008. The season featured several deadly tropical cyclones, including cyclones Senyar and Ditwah. Senyar was the first recorded cyclone to form in the Strait of Malacca, producing deadly floods across Indonesia, Thailand, and Malaysia and claiming over 1,501 lives, with Cyclone Ditwah meandered near Sri Lanka for several days, killing 647 people in the country in November 2025. The season itself saw an above-average number of depressions forming, and an average amount of cyclonic storms forming. Seasons have no official bounds, but cyclones tend to form between April and December, with the peak from May to November. However, this year, the first cyclone attained that strength on October 3rd. These dates conventionally delimit the period of each year when most tropical cyclones form in the northern Indian Ocean.
The scope of this article is limited to the Indian Ocean in the Northern Hemisphere, east of the Horn of Africa and west of the Malay Peninsula. There are two main seas in the North Indian Ocean—the Arabian Sea to the west of the Indian subcontinent, abbreviated ARB by the India Meteorological Department (IMD); and the Bay of Bengal to the east as BOB. The systems that form over land are abbreviated as LAND.
The official Regional Specialized Meteorological Centre in this basin is the IMD, while the Joint Typhoon Warning Center (JTWC) releases unofficial advisories. On average, four to five cyclonic storms form in this basin every season.
Season summary
A depression formed on 24 May in the Arabian Sea off the coast of Konkan, named ARB 01. It made a landfall on India soon after, bringing heavy rain to the region after degrading into a tropical low. It peaked with 30 mph 3-min winds and a minimum barometric pressure of 997 hPa (mbar). On 29 May, Depression BOB 01 formed near West Bengal. It strengthened into a Deep Depression three hours later on the IMD scale. It made landfall on the border of West Bengal and Bangladesh 6 hours later at its peak of 35 mph 3-min winds and a minimum barometric pressure of 988 hPa (mbar). It weakened and dissipated over Bangladesh over the next 36 hours, bringing heavy rain to the region. 65 people died from the resulting landslides and flooding.
After a lull in activity, Depression BOB 02 formed over West Bengal on 14 July from a well-marked low that moved inland a day prior. The next day, another depression was designated LAND 01. It quickly dissipated after forming over Northwestern India. BOB 02 dissipated but soon regenerated, causing it to be assigned a new name, LAND 03, despite there being no recorded evidence of a LAND 02. Soon after it dissipated for good, a new Depression emerged in the extreme northern Bay of Bengal, designated as BOB 04, but, similar to BOB 02/LAND 03, there was no evidence of a BOB 03. It moved inland and soon dissipated, but brought extreme rain and flooding to the affected areas.
Systems
Depression ARB 01
On 21 May, a tropical disturbance designated as Invest 93A formed in the Arabian Sea near the west coast of India, approximately 165 nautical miles (306 km) south-southwest of Mumbai. Favorable environmental conditions including warm sea surface temperatures and moderate wind shear allowed the system to gradually consolidate. The India Meteorological Department (IMD) forecasted its intensification into a cyclonic storm within 2 to 3 days, prompting orange and yellow weather warnings along the Konkan and Gujarat coasts, as well as widespread rainfall alerts across Kerala. This system marked the onset of tropical cyclone activity in the North Indian Ocean basin for the 2025 season.
Under the influence of the tropical disturbance, a low pressure area formed over the eastern Arabian Sea off the southern Konkan-Goa coasts by 05:30 IST on 22 May. By 05:30 IST on 23 May, it became a well marked low pressure area off the southern Konkan coast and persisted over the same region as of 08:30 IST. The system organised into a depression by 05:30 IST on 24 May about 40 km northwest of Ratnagiri. Over the next 6 hours, the depression moved slowly eastward at a speed of 5 km/h and between 11:30 and 12:30 IST it made landfall, crossing the south Konkan coast near Ratnagiri. The maximum sustained windspeed at the time was 25 knots (46 km/h) gusting to 35 knots (65 km/h). The system then moved eastwards inland, and by 05:30 IST on 25 May, the system had weakened back into a well marked low pressure area over southern Madhya Maharastra and the adjoining regions of Marathwada and Karnataka.
Deep Depression BOB 01
A low pressure area formed over northwest Bay of Bengal off the coast of Odisha at 08:30 IST on 27 May. Favorable environmental conditions including warm sea surface temperatures, moderate vertical wind shear over the system and the presence of warm air over Gangetic West Bengal and Bangladesh allowed it to gradually consolidate. However, the strong wind shear in the region due to the advancing southwest monsoon and insufficient time over sea before landfall limited its intensification. It became well marked at 05:30 IST on 28 May and persisted over the same region. By 05:30 IST on 29 May, the system coalesced into a depression near the coasts of West Bengal and Bangladesh. Thereafter, the depression moved nearly northwards and by 08:30 IST on the same day, it intensified into a deep depression. Over the next 6 hours, the system continued to move nearly northwards and made landfall on the West Bengal–Bangladesh coast between Sagar Island and Khepupara, close to Raidighi. Its maximum sustained windspeed at the time was 30 knots (56 km/h) gusting to 40 knots (74 km/h). It then tracked north-northeastward inland, and by 05:30 IST on 30 May the system had weakened back into a depression over Bangladesh. By 17:30 IST on the same day, it had degenerated into a well marked low over Meghalaya due to interaction with rugged terrain.
As a result of the system, Noakhali received 168 mm (6.6 in) and Dhaka 88 mm (3.5 in) of rainfall on 29 May. The same day, Kolkata received light to moderate rainfall with Jinjirabazar receiving 23 mm (0.91 in) of rainfall in a timespan from noon to 20:00 IST. It caused floods and landslides which killed 61, left 10 missing and affected 6.1 million people in India, with 27 deaths in Assam, 12 in Arunachal Pradesh, 6 each in Meghalaya and Mizoram, 4 in Manipur, 3 in Sikkim, 2 in Tripura and 1 in Nagaland. Four additional deaths occurred in Bangladesh, including 2 in Dhaka and 1 in Moheshkhali, while 8 others went missing when a trawler sank near Kutubdia. In Moheshkhali and Kutubdia, over 100 homes and farmland were flooded. Another person was killed by a collapsing wall, 11 were injured by lightning strikes, over 1,400 homes were damaged and 53 landslides were observed across 33 Rohingya refugee camps. The system brought heavy rainfall and strong winds to Myanmar as well. As a result, 26 homes were destroyed and 22 others were damaged in Yegyi and Dedaye Townships.
Depression BOB 02/LAND 03
On 14 July, a circulation previously marked as a well-defined low consolidated into a depression while over West Bengal, near Bangladesh, at 06:00 UTC. It weakened to a well-defined low on 16 July with it re-intensifying to a depression on the next day, according to the IMD.
Depression LAND 01
On 13 July, an upper air cyclonic circulation developed over parts of north Madhya. The IMD forecasted a low-pressure area to form under its influence over northwest Madhya during the next 24 hours.
Sometime during the late hours of 13 July or the early hours of 14 July, the forecasted low-pressure area formed over northwest Madhya, the active monsoon trough contributing to its rapid development.
On 15 July, the low pressure area became well-marked as of 08:30 IST (03:00 UTC) over parts of north Rajasthan and concentrated into a depression. The IMD forecasted the newly-formed depression to move west-northwestwards during the next 24 hours across parts of north Rajasthan. On 16 July, the depression weakened into a well-marked low over northwest Rajasthan at 05:30 IST (00:00 UTC) due to loss of moisture and topographical interaction.
The IMD issued red alerts across Rajasthan due to heavy forecasted rain. Isolated extremely heavy rainfall (over 21 cm) was forecasted by the IMD in southwest Rajasthan and north Gujarat. The highest rainfall recorded as a result of the depression was 234 mm in Nainwa of the Bundi district. 10 casualties were reported. The depression contributed to widespread flooding and financial losses. Many villages were cut off as rivers, drains, and dams overflowed. 17 people became stranded in the Banas River of Tonk, but were fortunately rescued by authorities. Flash floods across cities like Kota and Jaipur affected Rajasthan's economy, damaging roads and submerging farmlands.
Depression BOB 04
The remnants of Tropical Storm Wipha continued developing over the North Indian Ocean on 23 July. On 25 July, the low-pressure area over the Northwestern part of the Bay of Bengal concentrated into a depression by the IMD at 05:30 IST (00:00 UTC).
As a result of the depression, Pagladanga in Kolkata recorded 186 mm (7.3 in) in 15 hours from 24 July to 25 July, while Alipore recorded 120 mm (4.7 in) in 24 hours. Gusts of 50 km/h (31 mph; 27 kn) were also reported from the city. Many parts of the city were waterlogged.
Depression BOB 05
On 17 August, a low pressure area formed over the northwestern Bay of Bengal off the coasts of north Andhra and south Odisha under the influence of an upper air cyclonic circulation located over the same area as of 08:30 IST (03:00 UTC) according to the IMD.
The IMD began to track the system as it developed further, forecasting the low pressure area to concentrate into a depression. On 18 August, the low pressure area became well-marked as of 05:30 IST (00:00 UTC), persisting over the same regions. It concentrated into a depression as of 17:30 IST (12:00 UTC).
The IMD forecasted the newly-formed depression to move northwestwards and make landfall along south Odisha and north Andhra coasts around 08:30 IST (03:00 UTC) on 19 August. This prompted the IMD to issue orange and yellow rainfall alerts to districts across Odisha and Andhra Pradesh. After it moved inland, it degenerated into a well marked low the next day.
Deep Depression LAND 04
The remnants of Tropical Storm Nongfa from the South China sea in the Western Pacific basin contributed to the development of the depression. On 31 August, an upper air cyclonic circulation over the northwestern Bay of Bengal would help a low pressure to develop on 2 September. It would further develop into a well-marked low on 3 September. It then moved inland over northern Odisha on 4 September and weakened into a low pressure area over northern Chhattisgarh. Then on 5 September, it developed into a well-marked low pressure area again western Madhya Pradesh. At 23:30 IST on 6 September, the low further developed into a depression over southwestern Rajasthan. The depression continued to intensify and became a deep depression at 11:30 IST on 7 September over northern Gujarat. The deep depression moved into southeastern Pakistan the next day. It then weakened to a depression at 23:30 IST on 9 September. On 10 September, it would move offshore into the northeastern Arabian Sea. The system would further weaken to a well-marked low the next day over the northwestern Arabian Sea.
Depression BOB 06
On 21 September an upper air cyclonic circulation over the northeast Bay of Bengal developed into a low pressure on 22 September. It would develop into a well-marked low on 26 September. By 2:15 IST on 27 September, it would further develop into a depression. It then crossed the coast of South Odisha at 4:30 IST and moved inland. At 8:30 IST on 28 September the system weakened to a well-marked low-pressure area over West Vidarbha. The well-marked low moved over the Gulf of Cambay and eventually emerged over the Arabian Sea, where it would develop into Cyclone Shakhti.
The Harsul circle in Chhatrapati Sambhajinagar recorded 196 mm of rainfall over 24 hours. Over 11,500 were evacuated in Marathwada. The heavy rainfall and flooding led to the deaths of two in Dharashiv.