An analysis of the daily district wise rainfall data from India Meteorological Department (IMD) for the month of September 2021, the last month of India’s South West Monsoon 2021 shows that there were 489 instances when district rainfall of a day was above 50 mm. The normal monthly rainfall of India for Sept is 170.2 mm and actual rainfall was a huge 34.96% above normal at 229.7 mm[i], the actual average daily rainfall in this month was about 7.66 mm. Such high rainfall instances included 374 instances when rainfall was 50-100 mm, 84 instances when it was 100-150 mm, 20 times it was 150-200 mm and eleven times above 200 mm.
Interestingly, in June 2021[ii], July 2021[iii] and Aug 2021[iv] there were seven, seven and just one instances respectively when rainfall was above 200 mm, the eleven instances recorded in Sept 2021 is thus a record for this year. Similarly, the number of instances in Sept 2021 when rainfall was in the range 150-200 mm, at twenty is also a record for 2021 and such instances in June, July and Sept were five, seventeen and eleven. Detailed articles on June[v], July[vi] and Aug 2021[vii] provide more information about district wise, state wise rainfall in respective months.
Out of 694 districts of India, 278 districts or about 40.06% of the districts experienced such high rainfall in Sept 2021, many districts had more than one such high rainfall days. The highest number of such instances were seen (in June & July 2021 Konkan had the highest number of such instances, 48 & 56 respectively while in Aug, Meghalaya had the highest such numbers at 41 instances) in East Uttar Pradesh, where for the 42 districts (only 30 of them saw such instances) there were 45 instances when rainfall was above 50 mm. Odisha was second with 40 instances involving 22 of Odisha’s 30 districts. Incidentally, Assam had 46 such instances in June 2021, 31 in July 2021 and 26 in August 2021 and now 18 in Sept 2021.
Among the five regions of India (North, South, East, West and North East), West India had the highest number of such instances (173), followed by East India (149) and South India (82). North East India had the least such instances in Sept 2021 at 37.
North East India In the table below are given the number of such high rainfall district days in each of the states in North East India in each of the rainfall categories in Sept 2021.
| State | Districts that had over 50 mm rainfall at least on one day in Sep 2021 (Total no of districts) | No of district days when rainfall 50-100 mm | No of district days when Rainfall 100-150 mm | No of district days when Rainfall 150-200 | No of district days when Rainfall over 200 mm | Total no of district days when rainfall over 50 mm |
| Arunachal Pradesh | 4 (16) | 5 | 0 | 0 | 0 | 5 |
| Assam | 13 (27) | 16 | 1 | 1 | 0 | 18 |
| Meghalaya | 1 (7) | 1 | 0 | 0 | 0 | 1 |
| Nagaland | 2 (11) | 2 | 0 | 0 | 0 | 2 |
| Manipur | 0 (9) | 0 | 0 | 0 | 0 | 0 |
| Mizoram | 6 (8) | 7 | 1 | 0 | 0 | 8 |
| Tripura | 2 (4) | 2 | 0 | 0 | 0 | 2 |
| Sikkim | 1 (4) | 1 | 0 | 0 | 0 | 1 |
| North East India | 29 (86) | 34 | 2 | 1 | 0 | 37 |
East India
| State | Districts that had over 50 mm rainfall at least on one day in Sep 2021 (Total no of districts) | No of district days when rainfall 50-100 mm | No of district days when Rainfall 100-150 mm | No of district days when Rainfall 150-200 | No of district days when Rainfall over 200 mm | Total no of district days when rainfall over 50 mm |
| W Bengal | 13 (19) | 17 | 12 | 2 | 3 | 34 |
| Odisha | 22 (30) | 21 | 10 | 6 | 3 | 40 |
| Jharkhand | 20 (24) | 17 | 2 | 1 | 2 | 22 |
| Bihar | 3 (38) | 3 | 0 | 0 | 0 | 3 |
| Uttar Pradesh | 35 (74) | 33 | 13 | 3 | 1 | 50 |
| East India | 93 (185) | 91 | 37 | 12 | 9 | 149 |
North India
| State/ Union Territory | Districts that had over 50 mm rainfall at least on one day in Sep 2021 (Total no of districts) | No of district days when rainfall 50-100 mm | No of district days when Rainfall 100-150 mm | No of district days when Rainfall 150-200 | No of district days when Rainfall over 200 mm | Total no of district days when rainfall over 50 mm |
| Uttarakhand | 1 (13) | 1 | 0 | 0 | 0 | 1 |
| Haryana | 10 (22) | 13 | 0 | 0 | 0 | 13 |
| Chandigarh | 0 (1) | 0 | 0 | 0 | 0 | 0 |
| Delhi | 8 (9) | 15 | 1 | 1 | 0 | 17 |
| Punjab | 9 (22) | 10 | 1 | 0 | 0 | 11 |
| Himachal Pradesh | 2 (12) | 2 | 0 | 0 | 0 | 2 |
| Jammu & Kashmir | 3 (20) | 4 | 0 | 0 | 0 | 4 |
| Ladakh | 0 (2) | 0 | 0 | 0 | 0 | 0 |
| North India | 33 (101) | 45 | 2 | 1 | 0 | 48 |
West India
| State | Districts that had over 50 mm rainfall at least on one day in Sep 2021 (Total no of districts) | No of district days when rainfall 50-100 mm | No of district days when Rainfall 100-150 mm | No of district days when Rainfall 150-200 | No of district days when Rainfall over 200 mm | Total no of district days when rainfall over 50 mm |
| Rajasthan | 2 (33) | 2 | 0 | 0 | 0 | 2 |
| Madhya Pradesh | 14 (51) | 15 | 0 | 0 | 0 | 15 |
| Diu Daman | 2 (2) | 6 | 0 | 0 | 1 | 7 |
| Gujarat | 20 (34) | 44 | 17 | 2 | 0 | 63 |
| Dadra Nagarhaveli | 1 (1) | 4 | 2 | 1 | 1 | 8 |
| Goa | 2 (2) | 3 | 0 | 0 | 0 | 3 |
| Maharashtra | 20 (36) | 48 | 8 | 1 | 0 | 57 |
| Chhattisgarh | 14 (27) | 16 | 2 | 0 | 0 | 18 |
| West India | 75 (186) | 138 | 29 | 4 | 2 | 173 |
South India
| State | Districts that had over 50 mm rainfall at least on one day in Sep 2021 (Total no of districts) | No of district days when rainfall 50-100 mm | No of district days when Rainfall 100-150 mm | No of district days when Rainfall 150-200 | No of district days when Rainfall over 200 mm | Total no of district days when rainfall over 50 mm |
| Andhra Pradesh | 6 (13) | 8 | 2 | 0 | 0 | 10 |
| Telangana | 22 (33) | 26 | 11 | 2 | 0 | 39 |
| Tamil Nadu | 3 (38) | 3 | 0 | 0 | 0 | 3 |
| Puducherry | 3 (4) | 5 | 0 | 0 | 0 | 5 |
| Karnataka | 5 (30) | 7 | 0 | 0 | 0 | 7 |
| Kerala | 6 (14) | 7 | 1 | 0 | 0 | 8 |
| Lakshadweep | 0 (1) | 0 | 0 | 0 | 0 | 0 |
| Andaman & Nicobar | 3 (3) | 10 | 0 | 0 | 0 | 10 |
| South India | 48 (136) | 66 | 14 | 2 | 0 | 82 |
Date wise High Rainfall Events In the table below we have given total daily high rainfall events in the same categories as above (50-100 mm, 100-150 mm, 150-200 mm, 200+ mm) in districts of India in September 2021.
| Date in Sept 2021 | No of district days when rainfall 50-100 mm | No of district days when rainfall 100-150 mm | No of district days when rainfall 150-200 mm | No of district days when rainfall over 200 mm | Total No of district days when rainfall over 50 mm |
| 1 | 20 | 7 | 0 | 1 | 28 |
| 2 | 17 | 5 | 2 | 0 | 24 |
| 3 | 3 | 0 | 0 | 0 | 3 |
| 4 | 8 | 0 | 0 | 0 | 8 |
| 5 | 6 | 0 | 0 | 0 | 6 |
| 6 | 3 | 0 | 0 | 0 | 3 |
| 7 | 28 | 9 | 3 | 0 | 40 |
| 8 | 25 | 1 | 0 | 0 | 26 |
| 9 | 9 | 4 | 0 | 0 | 13 |
| 10 | 3 | 0 | 0 | 0 | 3 |
| 11 | 8 | 0 | 0 | 0 | 8 |
| 12 | 9 | 0 | 0 | 0 | 9 |
| 13 | 15 | 5 | 2 | 2 | 24 |
| 14 | 19 | 10 | 7 | 1 | 37 |
| 15 | 20 | 5 | 0 | 2 | 27 |
| 16 | 22 | 8 | 1 | 0 | 31 |
| 17 | 14 | 6 | 2 | 1 | 23 |
| 18 | 8 | 0 | 0 | 0 | 8 |
| 19 | 6 | 0 | 0 | 0 | 6 |
| 20 | 5 | 1 | 0 | 0 | 6 |
| 21 | 7 | 2 | 0 | 0 | 9 |
| 22 | 17 | 1 | 0 | 0 | 18 |
| 23 | 13 | 1 | 0 | 0 | 14 |
| 24 | 19 | 0 | 0 | 0 | 19 |
| 25 | 2 | 1 | 0 | 0 | 3 |
| 26 | 2 | 0 | 0 | 0 | 2 |
| 27 | 15 | 3 | 0 | 0 | 18 |
| 28 | 21 | 3 | 0 | 0 | 24 |
| 29 | 19 | 10 | 0 | 1 | 30 |
| 30 | 11 | 2 | 3 | 3 | 19 |
| TOTAL IN SEPT 2021 | 374 | 84 | 20 | 11 | 489 |
INDIA
| Region | Districts that had over 50 mm rainfall at least on one day in Sept 2021 (Total no of districts) | No of district days when rainfall 50-100 mm | No of district days when Rainfall 100-150 mm | No of district days when Rainfall 150-200 | No of district days when Rainfall over 200 mm | Total no of district days when rainfall over 50 mm |
| North East | 29 (86) | 34 | 2 | 1 | 0 | 37 |
| East | 93 (185) | 91 | 37 | 12 | 9 | 149 |
| North | 33 (101) | 45 | 2 | 1 | 0 | 48 |
| West | 75 (186) | 138 | 29 | 4 | 2 | 173 |
| South | 48 (136) | 66 | 14 | 2 | 0 | 82 |
| INDIA | 278 (694) | 374 | 84 | 20 | 11 | 489 |
SANDRP (ht.sandrp@gmail.com)
END NOTES:
[i] https://sandrp.in/2021/09/30/sw-monsoon-2021-district-wise-rainfall-in-india/
[ii] https://sandrp.in/2021/07/23/high-rainfall-days-in-indias-districts-in-june-2021/
[iii] https://sandrp.in/2021/08/06/july-2021-high-rainfall-days-in-indias-districts/
[iv] https://sandrp.in/2021/09/02/high-rainfall-days-in-indias-districts-in-august-2021/
[v] https://sandrp.in/2021/06/30/june-2021-district-wise-rainfall-in-in-indias-sw-monsoon/
[vi] https://sandrp.in/2021/07/31/june-july-2021-district-wise-sw-monsoon-rainfall-in-india/
[vii] https://sandrp.in/2021/09/01/june-aug-2021-district-wise-rainfall-in-indias-sw-monsoon/
SANDRP 