The 2015 North Indian Ocean cyclone season was a below-average tropical cyclone season which featured the highest number of deaths since the 2010 season. Despite inactivity in the Bay of Bengal caused by the ongoing El Niño, the season produced an above-average number of tropical cyclones in the Arabian Sea. The first storm of the season, Ashobaa, formed on 7 June, while the final storm of the season, Megh, ultimately dissipated on 10 November. A total of twelve depressions were recorded, of which nine intensified into deep depressions. Of these nine, a total of four further strengthened into cyclonic storms, while two attained their peaks as extremely severe cyclonic storms.
This timeline documents tropical cyclone formations, strengthening, weakening, landfalls, extratropical transitions, and dissipations during the season. The time stamp for each event is stated using Coordinated Universal Time (UTC), the 24-hour clock where 00:00 = midnight UTC. Additionally, figures for maximum sustained winds and position estimates are rounded to the nearest 5 units (Kilometres or miles). Direct wind observations are rounded to the nearest whole number. Meteorological observations typically report atmospheric pressures are measured in hectopascals per the recommendation of the World Meteorological Organization, and the nearest hundredth of an inches of mercury or millibars (hectopascals).
The India Meteorological Department (IMD) is the official Regional Specialized Meteorological Centre for the Northern Indian Ocean basin, and as such, it is responsible for tracking and issuing advisories on systems in the Arabian Sea and in the Bay of Bengal. If tropical cyclones in the Northern Indian Ocean reach winds of , it is given a name from a pre-defined naming list. The Joint Typhoon Warning Center (JTWC) unofficially issues advisories on systems in the Northern Indian Ocean, assigning tropical cyclones a numerical identifier and suffixing it with the letter A for systems in the Arabian Sra and B for systems in the Bay of Bengal. The IMD measures tropical cyclone wind speeds over a 3-minute average while the JTWC uses a 1-minute average.
Timeline of events
June
6 June 06:00 UTCUTC stands for Coordinated Universal Time. (11:30 a.m. ISTIST stands for Indian Standard Time, which is equivalent to UTC+5:30.) at – The Joint Typhoon Warning Center (JTWC) reports that Tropical Depression 01A has formed from an area of low pressure while located roughly northwest of Lakshadweep, India. 7 June 03:00 UTC (8:30 a.m. IST) at – The India Meteorological Department (IMD) designates Tropical Depression 01A as Depression ARB 01 while the system is located roughly west of Goa. 06:00 UTC (11:30 a.m. IST) at – The JTWC reports that Tropical Depression ARB 01 (01A) has intensified into a tropical storm while located roughly west of Goa. 8 June 00:00 UTC (5:30 a.m. IST) at – The IMD reports that Depression ARB 01 (01A) has intensified into a deep depression while located roughly west of Porbandar, Gujarat. 03:00 UTC (8:30 a.m. IST) at – The IMD reports that Deep Depression ARB 01 (01A) has intensified into a cyclonic storm and names it "Ashobaa" while the system is located roughly west of Porbandar, Gujarat. 9 June 18:00 UTC (11:30 p.m. IST) at – The IMD reports that Cyclonic Storm Ashobaa (01A) has reached its peak intensity, with maximum 3-minute sustained wind speeds of , while located roughly southeast of Muscat, Oman. 18:00 UTC (11:30 p.m. IST) at – The JTWC reports that Tropical Storm Ashobaa (01A) has reached its peak intensity, with maximum 1-minute sustained wind speeds of , while located roughly southeast of Muscat, Oman. 11 June 18:00 UTC (11:30 p.m. IST) at – The IMD reports that Cyclonic Storm Ashobaa (01A) has weakened into a deep depression while located roughly southeast of Muscat, Oman.
12 June 00:00 UTC (5:30 a.m. IST) at – The IMD reports that Deep Depression ex-Ashobaa (01A) has weakened into a depression while located roughly southeast of Muscat, Oman. 06:00 UTC (11:30 a.m. IST) at – The JTWC reports that Tropical Storm Ashobaa (01A) has weakened into a tropical depression and dissipated while located roughly southeast of Muscat, Oman. 12:00 UTC (5:30 p.m. IST) at – The IMD reports that Depression ex-Ashobaa (01A) has weakened into a well-marked low-pressure area while located roughly southeast of Muscat, Oman. 20 June 03:00 UTC (8:30 a.m. IST) at – The IMD reports that Depression BOB 01 has formed while located roughly south of Bhubaneswar, Odisha. Simultaneously, they report that the system has reached its peak intensity, with maximum 3-minute sustained wind speeds of . 20:00–21:00 UTC (1:30–2:30 a.m. IST, 21 June) at – The IMD reports that Depression BOB 01 has made landfall on the Odia coast between Gopalpur and Puri with maximum 3-minute sustained wind speeds of . 22 June 00:00 UTC (5:30 a.m. IST) at – The IMD reports that Depression BOB 01 has weakened into a well-marked low-pressure area while located over the Indian states of Odisha, Jharkhand and Chhattisgarh. 03:00 UTC (8:30 a.m. IST) at – The IMD reports that Depression ARB 02 has formed while located roughly southwest of Porbandar, Gujarat.
23 June 03:00 UTC (8:30 a.m. IST) at – The IMD reports that Depression ARB 02 has intensified into a deep depression while located roughly southwest of Diu, Daman and Diu. Simultaneously, they report that the system has reached its peak intensity, with maximum 3-minute sustained wind speeds of . 09:00–10:00 UTC (2:30–3:30 p.m. IST) at – The IMD reports that Deep Depression ARB 02 has made landfall near Diu with maximum 3-minute sustained wind speeds of . 24 June 12:00 UTC (5:30 p.m. IST) at – The IMD reports that Deep Depression ARB 02 has weakened into a depression while located roughly south of Udaipur, Rajasthan. 25 June 00:00 UTC (5:30 a.m. IST) at – The IMD reports that Depression ARB 02 has weakened into a well-marked low-pressure area while located over northwestern Madhya Pradesh.
July 10 July 03:00 UTC (8:30 a.m. IST) at – The IMD reports that Depression LAND 01 has formed while located over Jharkhand. Simultaneously, they report that the system has reached its peak intensity, with maximum 3-minute sustained wind speeds of . 12 July 12:00 UTC (5:30 p.m. IST) at – The IMD reports that Depression LAND 01 has weakened into a well-marked low-pressure area while located over northwestern Uttar Pradesh and neighboring Haryana. 26 July 00:00 UTC (5:30 a.m. IST) at – The IMD reports that Depression BOB 02 has formed while located roughly west of Chittagong, Bangladesh. 27 July 12:00 UTC (5:30 p.m. IST) at – The IMD reports that Depression LAND 02 has formed while located over southwestern Rajasthan and neighboring Gujarat.
28 July 03:00 UTC (8:30 a.m. IST) at – The IMD reports that Depression LAND 02 has intensified into a deep depression while located roughly southwest of Jodhpur, Rajasthan. Simultaneously, they report that the system has reached its peak intensity, with maximum 3-minute sustained wind speeds of . 06:00 UTC (11:30 a.m. IST) at – The JTWC designates Depression BOB 02 as Tropical Depression 02B while the system is located roughly southwest of Cox's Bazar, Bangladesh. 29 July 00:00 UTC (5:30 a.m. IST) at – The IMD reports that Depression BOB 02 (02B) has intensified into a deep depression while located roughly southwest of Cox's Bazar, Bangladesh. 00:00 UTC (5:30 a.m. IST) at – The JTWC reports that Tropical Depression BOB 02 (02B) has intensified into a tropical storm while located roughly southwest of Cox's Bazar, Bangladesh. 00:00 UTC (5:30 a.m. IST) at – The IMD reports that Deep Depression LAND 02 has weakened into a depression while located roughly northwest of Jodhpur, Rajasthan. 18:00 UTC (11:30 p.m. IST) at – The IMD reports that Deep Depression BOB 02 (02B) has intensified into a cyclonic storm and names it "Komen" while the system is located roughly west of Cox's Bazar, Bangladesh. 30 July 00:00 UTC (5:30 a.m. IST) at – The JTWC reports that Tropical Storm Komen (02B) has reached its peak intensity, with maximum 1-minute sustained wind speeds of while located roughly west of Cox's Bazar, Bangladesh. 03:00 UTC (8:30 a.m. IST) at – The IMD reports that Depression LAND 02 has weakened into a well-marked area of low pressure while located over western Rajasthan. 06:00 UTC (11:30 a.m. IST) at – The IMD reports that Cyclonic Storm Komen (02B) has reached its peak intensity, with maximum 3-minute sustained wind speeds of . 14:00–15:00 UTC (7:30–8:30 p.m. IST) at – The IMD reports that Cyclonic Storm Komen (02B) has made landfall with maximum 3-minute sustained wind speeds of while located roughly west of Chittagong, Bangladesh. 21:00 UTC (2:30 a.m. IST, 31 July) at – The IMD reports that Cyclonic Storm Komen (02B) has weakened into a deep depression while located roughly south of Agartala, Tripura. 31 July 00:00 UTC (5:30 a.m. IST) at – The JTWC reports that Tropical Storm Komen (02B) has weakened into a tropical depression and dissipated while located roughly south of Agartala, Tripura. 12:00 UTC (5:30 p.m. IST) at – The IMD reports that Deep Depression ex-Komen (02B) has weakened into a depression while located roughly southwest of Dhaka, Bangladesh.
August
2 August 12:00 UTC (5:30 p.m. IST) at – The IMD reports that Depression ex-Komen (02B) has weakened into a well-marked area of low pressure over Jharkhand and northern Odisha and Chhattisgarh. 4 August 03:00 UTC (8:30 a.m. IST) at – The IMD reports that Depression LAND 03 has formed while located over eastern Madhya Pradesh and neighboring Chhattisgarh. Simultaneously, they report that the system has attained its peak intensity, with maximum 3-minute sustained wind speeds of . 5 August 00:00 UTC (5:30 a.m. IST) at – The IMD reports that Depression LAND 03 has weakened into a well-marked low-pressure area while located over southwestern Madhya Pradesh.
September 16 September 03:00 UTC (8:30 a.m. IST) at – The IMD reports that Depression LAND 04 has formed from an area of low pressure while located over southern Odisha. 17 September 03:00 UTC (8:30 a.m. IST) at – The IMD reports that Depression LAND 04 has intensified into a deep depression while located roughly east of Nagpur, Maharashtra. Simultaneously, they report that the system has reached its peak intensity with maximum 3-minute sustained wind speeds of . 18 September 03:00 UTC (8:30 a.m. IST) at – The IMD reports that Deep Depression LAND 04 has weakened into a depression while located roughly northeast of Aurangabad, Maharashtra. 19 September 03:00 UTC (8:30 a.m. IST) at – The IMD reports that Depression LAND 04 has weakened into a well-marked area of low pressure while located over northern Maharashtra and neighboring areas of southwestern Madhya Pradesh and Gujarat.
October 7 October 00:00 UTC (5:30 a.m. IST) at – The JTWC reports that Tropical Depression 03A has formed from an area of low pressure while located roughly northwest of Lakshadweep, India.
9 October 00:00 UTC (5:30 a.m. IST) at – The IMD designates Tropical Depression 03A as Depression ARB 03 while the system is located roughly west of Goa. 06:00 UTC (11:30 a.m. IST) at – The JTWC reports that Tropical Depression ARB 03 (03A) has intensified into a tropical storm while located roughly northwest of Lakshadweep, India. Simultaneously, they report that the storm has reached its peak intensity, with maximum 1-minute sustained wind speeds of . 12:00 UTC (5:30 p.m. IST) at – The JTWC reports that Tropical Storm ARB 03 (03A) has weakened into a tropical depression while located roughly west of Goa. 18:00 UTC (11:30 p.m. IST) at – The IMD reports that Depression ARB 03 (03A) has intensified into a deep depression while located roughly west of Goa. Simultaneously, they report that the system has reached its peak intensity, with maximum 3-minute sustained wind speeds of . 11 October