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Informist, Friday, Jul. 4, 2025

LATEST DEVELOPMENTS

The southwest monsoon was active over parts of northwest, east, and central India during the week and caused torrential rain across several parts of the country. In the mountainous states of Himachal Pradesh and Uttarakhand, the monsoon wreaked havoc, with flash floods and landslides claiming many lives.

The India Meteorological Department had issued an orange alert for several states and Union territories in northwest India such as Uttarakhand, Punjab, Haryana, Chandigarh, and Delhi for Sunday and Monday. The weather bureau had also issued an orange alert for Himachal Pradesh from Saturday to Monday and for parts of Rajasthan till Saturday. The department Thursday said similar weather is expected in Himachal Pradesh and Uttarakhand over the next five days and over Punjab, Haryana, and west Rajasthan till Monday.

Several parts of Rajasthan, Gujarat region, Goa, the ghat areas of central Maharashtra, and coastal Karnataka received heavy, very heavy, or extremely heavy rainfall during the week, the weather bureau said. The department had issued a red alert for extremely heavy rainfall in Rajasthan.

Because of the heavy rains, the weather agency had warned of moderate flash floods in a few watersheds and neighbourhood districts of Himachal Pradesh, Uttarakhand, Arunachal Pradesh, Assam, Meghalaya, Nagaland, and Manipur as well as in several districts of sub-Himalayan West Bengal, Sikkim, and coastal Karnataka till Friday. Low to moderate flash floods were also said to be likely in a few watersheds and neighbourhoods of western Rajasthan.

The southwest monsoon is in an active phase and will bring heavy to very heavy rainfall over several parts of the country in the next 6–7 days, the department said. Under the influence of a low pressure area and an east-west trough, multiple parts of east and central India are likely to receive heavy to very heavy rainfall in the next seven days, it said.

For July, the weather bureau has forecast above-normal rainfall for the country at over 106% of the long-period average. While this may bring relief to areas facing water scarcity, it may pose a risk of flooding and damage in regions prone to heavy rainfall. Given the forecast for above-normal rainfall, the bureau has highlighted the need for continuous monitoring and timely release of water from reservoirs to reduce the risks from excess rainfall. This is particularly crucial in eastern and central India, which have already seen excess rains.

Though the country as a whole is expected to witness above-normal showers in July, the weather bureau also sees most parts of northeast and east India, as well as many areas of extreme south peninsular India and some areas of northwest India receiving below-normal rainfall.

Following is the weekly all-India rainfall since the beginning of the southwest monsoon season (in millimetres):

Following table gives subdivision-wise rainfall during Jun 1-Jul 4 in the country (in millimetres): 

MONSOON PROGRESS

This year, the southwest monsoon hit the Kerala coast on May 24, eight days ahead of its normal date of Jun. 1, and by May 29 the monsoon current covered southern and northeast India entirely, and parts of east and central India. However, after May 29, the monsoon was in a weak phase and resumed advancing only on Jun. 16. So far, the monsoon current has covered most parts of the country, except some parts of Haryana, Delhi, Chandigarh, Rajasthan, and Uttar Pradesh. Normally, beginning Jun. 1, the southwest monsoon advances northwards and covers the entire country around Jul. 8. The withdrawal of the monsoon starts around Sept. 17, and it withdraws from the entire country around Oct. 15. 

ONSET CRITERIA

At present, the department uses criteria that was adopted in 2016 for declaring the onset of the monsoon over Kerala, which is based on the daily rainfall at 14 stations in Kerala and the neighbouring area, along with wind-field and outgoing long-wave radiation over the southeast Arabian Sea.

If, after May 10, 60% of the 14 designated stations--Minicoy and Amini in Lakshadweep, Thiruvananthapuram, Punalur, Kollam, Allapuzha, Kottayam, Kochi, Thrissur, Kozhikode, Thalassery, and Kannur in Kerala, and Kudulu and Mangalore in Karnataka--report rainfall of 2.5 millimetres or more for two consecutive days, the onset over Kerala will be declared on the second day, provided the wind-field and outgoing long-wave radiation conditions are met.

The outgoing long-wave radiation measures the amount of terrestrial radiation released into space and, by extension, the amount of cloud cover and water vapour that intercepts that radiation in the atmosphere.

The criteria emphasise the sharp increase in rainfall over Kerala along with the setting up of large-scale monsoon flow and extension of westerlies up to 600 hectopascal. 

However, the department declares the monsoon onset or progress dates for other regions operationally in a subjective manner, considering the sharp increase in rainfall and its characteristic sustenance for a few days and associated changes in the atmospheric circulation features.

LONG-RANGE FORECAST

The India Meteorological Department has projected the southwest monsoon to be above normal at over 106% of the long-period average of 870 millimetres, which is based on historical data from 1971 to 2020. The forecast assumes a modelling error of plus or minus 4%, according to the second-stage long-range forecast for the Jun-Sept southwest monsoon season. The department had earlier predicted rainfall for Jun-Sept at 105% of the long-period average with a model error of plus or minus 5%.

The agency said that on average, it expects above-normal rainfall over most parts of the country this year except northeast India, where rainfall is expected to be lower than normal. Central and south peninsular India are expected to receive above-normal rainfall at 106% of the long-period average, while rainfall over the northwestern parts of the country is likely to be normal at 92-108% of the long-period average.

According to the bureau's forecasts for the season, there is 59% chance of above-normal monsoon rains and 31% chance of normal showers. The chances of below-normal precipitation stand at 8% and those of deficient showers are just 2%. 

The weather bureau predicts rainfall in June to be above normal at 108% of the long-period average. Normal to above-normal rainfall is very likely over most parts of the country in June. However, some southern parts of peninsular India and parts of northwest and northeast India are expected to record below-normal rainfall.

The latest climate models forecast that weak negative Indian Ocean Dipole conditions are likely to persist during the southwest monsoon period. The Indian Ocean Dipole is the difference in sea surface temperatures between the western and eastern tropical Indian Ocean. Usually, a negative Indian Ocean Dipole leads to less rainfall in India, while a positive dipole results in better rainfall.

The weak negative conditions will not affect the country's southwest monsoon as much as the El Nino-Southern Oscillation, India Meteorological Department Director General Mrutyunjay Mohapatra said. The weather department sees neutral El Nino-Southern Oscillation conditions prevailing over the equatorial Pacific region during Jun-Sept. 

The El Nino-Southern Oscillation refers to the fluctuation between El Nino and La Nina conditions in the Pacific Ocean. El Nino, which means Little Boy in Spanish, is a climate pattern marked by an unusual warming of the surface waters in the Pacific Ocean leading to drier, hotter weather in India. La Nina, which means Little Girl in Spanish, is the opposite of El Nino. It is an oceanic and atmospheric phenomenon that is associated with the colder sea surface temperatures. La Nina is usually associated with good rains in India. 

The department's long-range forecasts are as follows:

Private forecaster Skymet has predicted a 'normal' southwest monsoon at 103% of the long-period average with an error margin of plus or minus 5%. The agency had predicted a weak start to the monsoon this year but expects the rainfall to increase from July. It does not see any chance of the occurrence of El Nino.

PRE-MONSOON RAINFALL

While the monsoon arrived on May 24, the weather department said rainfall during May would not be factored into the southwest monsoon. The country received above-normal rainfall during the pre-monsoon period in Mar-May. India received 185.8 millimetres of rainfall during Mar-May, 42% above the normal for the period. Last year, it received 108.7 millimetres rainfall during Mar-May, 8.1% below the normal for the period.

RECAP 2024
The country received 934.8 millimetres of rainfall in Jun-Sept last year, which was 108% of the long-period average. The monsoon had hit the Kerala coast on May 30, two days ahead of the scheduled date, and covered the entire country by Jul. 2, six days ahead of the normal date of Jul. 8. The weather bureau's forecast for the monsoon onset over Kerala last year was May 31 and predicted rainfall during Jun-Sept 920.7 millimetres, or 96% of the long-period average.     

Overall, monsoon rainfall was above normal for the season and the spatial distribution was uniform. The rainfall in June was below-normal at 89% of the long-period average. However, the country received above-normal showers during the rest of the southwest monsoon period. Rainfall was 109% of the long-period average in July, 115% in August, and 112% in September.

Rainfall during the season was 107% of the long-period average in northwest India, 119% in central India, 86% in east and northeast India, and 114% in the southern peninsula. Of the total 36 meteorological subdivisions, two subdivisions received large excess, 10 received excess, and 21 recorded normal rainfall. Three subdivisions received deficient rainfall during Jun-Sept last year – Arunachal Pradesh, Punjab, Jammu & Kashmir, and Ladakh.

RESERVOIR LEVELS

The water level in 161 key reservoirs across India rose significantly by 76% on year to 66.449 billion cubic metres as of Thursday, according to data from the Central Water Commission. The water level rose from the previous week's level of 58.030 billion cubic metres as the monsoon re-entered its active phase Jun. 16 and started replenishing the reservoirs. The current level is 36.42% of the total live storage capacity of 182.444 billion cubic metres.

The water level in reservoirs in the northern region stood at 5.928 billion cubic metres, or 29.89% of the total live storage capacity, up from 27.01% a year ago. The northern region includes Rajasthan, Himachal Pradesh, and Punjab.

Reservoirs in the eastern region held 6.696 billion cubic metres of water, which is 30.83% of their total live storage capacity. This was higher than 21.08% held by the reservoirs in the same period a year ago. The eastern region comprises Assam, Jharkhand, Odisha, Tripura, Nagaland, West Bengal, and Bihar.

In the western region, which comprises Maharashtra, Gujarat, and Goa, the water level in reservoirs was 14.554 billion cubic metres. This marks a six-year high, according to data collated by Informist. As of Thursday, the water level was 38.96% of the total live storage capacity, compared with 20.19% a year ago.

The water level in the southern region was 24.968 billion cubic metres, again a six-year high. As of Thursday, the water level was 45.45% of the total live storage capacity of the 45 reservoirs in the region. This region includes Andhra Pradesh, Telangana, Karnataka, Kerala, and Tamil Nadu. At this time last year, the water level was just 15.45% of the total live storage capacity. 

The current live storage capacity of these 161 reservoirs is 182.444 billion cubic metres. Water in these reservoirs, which is used for irrigation and generating electricity, is replenished during the monsoon season.

SOWING

Farmers across the country had planted kharif crops across 26.2 million hectares as of Jun. 27, up 11.5% from 23.5 million hectares a year ago, according to data released by the Ministry of Agriculture and Farmers Welfare. The sowing of kharif crops has begun well due to the early onset of the southwest monsoon. The forecast of above-normal rainfall has boosted the acreage of key crops such as paddy, pulses, coarse cereals, and cotton.

The area under paddy, one of the main kharif crops, was up over 47% on year at 3.50 million hectares, as of Jun. 27. The area under pulses rose to  2.1 million hectares, up over 37% from 1.5 million hectares last year. Under pulses, the acreage of urad and moong rose from last year, but the area under tur, the largest kharif pulses crop, was down nearly 4% on year at 835,000 hectares. 

Soybean acreage was up 1% at 3.2 million hectares. The area under cotton was down nearly 9% on year at 5.5 million hectares. The acreage of maize was up 11% on year at 2.4 million hectares as of Jun. 27.   

TERMS

LARGE EXCESS: Percentage departure of actual rainfall from normal rainfall is 60% or more 

EXCESS: Percentage departure of actual rainfall from normal rainfall is 20-59% 

NORMAL: Percentage departure of actual rainfall from normal rainfall is -19% to +19%

DEFICIENT: Percentage departure of actual rainfall from normal rainfall is (-)59-20%

LARGE DEFICIENT: Percentage departure of actual rainfall from normal rainfall is (-)99-60%

NORMAL: Percentage departure of actual rainfall is within +/-10% of the long period average

BELOW NORMAL: Percentage departure of actual rainfall is <10% of the long period average

ABOVE NORMAL: Percentage departure of actual rainfall is within >10% of the long period average

EXCEPTIONALLY HEAVY RAINFALL: Rainfall realised in a day is a value near about the highest recorded rainfall at or near the station for the month or season. However, this term will be used only when the actual rainfall amount exceeds 120 mm. 

EXTREMELY HEAVY RAIN: Amount of rainfall realised in a day is >/= 244.5 mm

VERY HEAVY RAIN: Amount of rainfall realised in a day is 124.5-244.4 mm

HEAVY RAIN: Amount of rainfall realised in a day is 64.5-124.4 mm

MODERATE RAIN: Amount of rainfall realised in a day is 7.6-35.5 mm 

RED ALERT: Very heavy rainfall of over 204.4 mm in 24 hours

ORANGE ALERT: Heavy rainfall of 115.6-204.4 mm in 24 hours 

YELLOW ALERT: Warning to be aware of worsening weather conditions that could disrupt daily life

End

Internet links:
India Meteorological Department - www.imd.gov.in
National Centre for Medium Range Weather Forecasting - www.ncmrwf.gov.in
Indian Institute of Tropical Meteorology - www.tropmet.res.in.  

Reported by Taniva Singha Roy

Edited by Rajeev Pai

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