Weather Update: Chennai could see another spell of sustained rainfall in the coming days as the northeast monsoon strengthens across Tamil Nadu. Showers swept across the city and parts of the northern
coastal belt overnight, while the water levels in Chennai’s drinking water reservoirs continued to improve, reaching around 41% of their combined capacity.
The India Meteorological Department (IMD) has forecast rain across several parts of Tamil Nadu until October 26, with thunderstorms, lightning and strong winds likely in some areas. Chennai and neighbouring districts are under a yellow alert for heavy rainfall, while orange warnings have been issued for very heavy rain in several districts, particularly along the Western Ghats.
The weather activity is linked to a low-pressure area over the Comorin Sea and adjoining parts of southern Tamil Nadu and Kerala. A separate system developing over the southeast Bay of Bengal could also influence rainfall patterns in the coming days.
Chennai Water Reservoirs Show Steady Improvement
The latest assessment of Chennai’s water-supply lakes, dated October 23, points to a gradual increase in storage following recent rainfall. The reservoirs are currently holding water equivalent to around 41% of their total capacity.
Further improvement is possible if the forecast rain materialises. The latest reservoir update indicates that showers are expected over the next three days, with at least one spell of sustained rainfall potentially generating stronger inflows into the lakes over the following week.
Chennai Water Supply Lakes position as on 23.10.2026 – Steady rise seen, with rains expected next 3 days with atelast one day spell, we can expect good increase in inflows in next one week.
— Tamil Nadu Weatherman (@praddy06) October 23, 2026
The increase will be important for Chennai’s water supply after the relatively dry conditions experienced recently. However, the actual gain in storage will depend on the intensity and distribution of rainfall across the catchment areas.
Chennai Under Yellow Alert As Heavy Rain Forecast
The Chennai Regional Meteorological Centre has forecast moderate to heavy rain in the city on Friday, October 23, accompanied by the possibility of thunderstorms and lightning.
The IMD has issued a yellow alert for Chennai and neighbouring districts, warning that isolated locations could receive between 6 cm and 12 cm of rain within 24 hours over the next four days. Heavy rainfall has also been forecast in 26 districts across Tamil Nadu on Friday, including Chennai and Tiruvallur.
The warning is expected to cover additional northern districts, including Chengalpattu and Kancheepuram, between October 24 and 26, alongside several delta and interior districts.
With cloud cover expected to persist, Chennai’s daytime temperature is likely to remain between 31°C and 32°C. Night-time temperatures are forecast to range from 25°C to 26°C.
The weather department has also warned of thunderstorms, lightning and gusty winds of 40-50 kmph in areas covered by the rainfall alerts.
District-Wise Rain Forecast From October 23 To 26
The IMD’s forecast indicates that rainfall will extend well beyond Chennai, with some districts facing the possibility of very heavy downpours.
October 23, Friday: Very heavy rain is likely at isolated places in Kanyakumari, the Nilgiris and Coimbatore districts, prompting an orange warning. Heavy rain accompanied by thunderstorms, lightning and winds of 40-50 kmph is possible in Erode, Salem, Namakkal, Karur, Tiruchirappalli, Theni, Tenkasi, Dindigul, Madurai, Virudhunagar, Pudukkottai, Thanjavur, Tiruvarur, Nagapattinam, Mayiladuthurai, Sivaganga, Ramanathapuram, Thoothukudi, Tirunelveli, Ariyalur, Cuddalore, Villupuram, Tiruppur, Perambalur, Chennai and Tiruvallur. Puducherry and Karaikal are also likely to receive heavy rain.
October 24, Saturday: The orange warning for very heavy rainfall will cover the hilly areas of Tirunelveli, along with Kanyakumari, Coimbatore and the Nilgiris. Heavy rain, accompanied by thunder, lightning and strong winds reaching 40-50 kmph, is possible in Tiruppur, Erode, Tiruchirappalli, Tiruvannamalai, Ariyalur, Perambalur, Pudukkottai, Madurai, Theni, Dindigul, Cuddalore, Villupuram, Kallakurichi, Thanjavur, Tiruvarur, Nagapattinam, Mayiladuthurai, Sivaganga, Chennai, Tiruvallur, Chengalpattu and Kancheepuram. Puducherry and Karaikal are also included in the forecast.
Severe storms all along north coastal TN including Chennai!! Whataa sight👌
#Chennairains #Monsoon2026 #SWM2026 #Tamilnadu https://t.co/uUwkJGdrmh
— Hrishi Jawahar (@jhrishi2) October 22, 2026
October 25, Sunday: Isolated very heavy rainfall is forecast in the Nilgiris, Coimbatore, Pudukkottai, Madurai, Dindigul, Sivaganga and Theni districts. Heavy rain with thunderstorms, lightning and strong winds is also possible in Tiruppur, Erode, Salem, Namakkal, Karur, Tiruchirappalli, Tiruvannamalai, Ariyalur, Perambalur, Cuddalore, Villupuram, Kallakurichi, Thanjavur, Tiruvarur, Nagapattinam, Mayiladuthurai, Kancheepuram, Chengalpattu, Tiruvallur and Chennai. Puducherry and Karaikal may also experience heavy showers.
October 26, Monday: Very heavy rain is likely at isolated locations in the Nilgiris, Coimbatore, Theni, Madurai, Sivaganga, Ramanathapuram and Pudukkottai districts. Heavy rain is forecast in Thanjavur, Tiruvarur, Nagapattinam, Mayiladuthurai, Namakkal, Erode, Tiruppur, Karur, Dindigul, Virudhunagar, Tenkasi, Tirunelveli, Kanyakumari, Tiruchirappalli, Thoothukudi, Perambalur, Ariyalur, Kallakurichi, Cuddalore, Villupuram, Dharmapuri, Salem, Vellore, Ranipet, Tiruvannamalai, Tiruvallur, Chennai, Tirupattur and Krishnagiri. Puducherry and Karaikal are also covered by the heavy-rain forecast.
The warnings indicate that rainfall will not be uniform across the state. While Chennai and other coastal areas may experience intermittent spells, southern districts and locations along the Western Ghats could face more intense downpours.
How The Comorin Sea System Is Influencing Tamil Nadu Weather
The low-pressure area responsible for the current spell of rain was previously located over the southwest Bay of Bengal before shifting towards the Comorin Sea and adjoining areas of southern Tamil Nadu and Kerala. Its associated cyclonic circulation extends to approximately 5.8 km above mean sea level. The system is drawing moisture into the region and helping air rise, cool and condense into rain-bearing clouds. This, together with atmospheric instability, is supporting the current spell of widespread rainfall.
An IMD official indicated that the system could move northwards, increasing the likelihood of rain over Chennai and surrounding areas. The city could therefore experience further moderate to heavy showers, with thunderstorms and lightning, while coastal districts may continue to receive rain intermittently.
Under the influence of the LPA over Comorin Sea and adjoining areas vigorous monsoon conditions likely to continue over Tamil Nadu and Kerala. Parts of South TN and isolated places in West TN may see heavy to very heavy rains as moisture gets dragged across Peninsular India. Coastal areas may continue to see on and off spells of rains. With the developing LPA in Southeast Bay likely to move towards Coastal AP there is a chance next week may see subdued rainfall activity for 3 / 4 days. More on it as things evolve.
— Chennai Rains (COMK) (@ChennaiRains) October 23, 2026
The prevailing conditions are also expected to maintain vigorous monsoon activity across Tamil Nadu and Kerala. Southern Tamil Nadu and isolated parts of western Tamil Nadu are particularly vulnerable to heavy or very heavy rain as moisture moves across the peninsula.
Tirupati Receives More Than 300 Mm Of Rain In 10 Days
The active weather pattern is also bringing substantial rainfall to neighbouring Andhra Pradesh. Praneeth, known as Andhra Pradesh Weatherman, reported that Tirupati had received more than 300 mm of rain over the 10 days leading up to October 23.
Rainfall has continued in repeated spells, and the city has been described in the updateas Andhra Pradesh’s rainiest city this year.
Further showers were expected in Tirupati and other parts of the district over the next two hours from the time of the update. Nellore was also identified as an area that could receive good rainfall.
#Tirupati city recieved 300 mm+ rainfall during last 10 days and still the rains are pouring in rounds, becoming the rainiest city in AP this year too. Next 2 hours, the rains will continue in the city and even the district, while #Nellore city can also see good rains. https://t.co/fSi3goMPj7
— Andhra Pradesh Weatherman (@praneethweather) October 23, 2026
The developments underline the broad reach of the current weather systems, which are affecting areas across southern India rather than Tamil Nadu alone.
Bay Of Bengal System Could Bring A Brief Change Next Week
Despite the forecast of continued rain until October 26, weather conditions could become less active in some areas after the weekend. A low-pressure area developing over the southeast Bay of Bengal is expected to move towards coastal Andhra Pradesh. Depending on its movement and development, rainfall activity over parts of the region could ease for three to four days next week.
The outlook remains subject to changes as the system evolves, and further updates are expected as its movement becomes clearer.
For Chennai, the immediate forecast remains favourable for additional rainfall and rising reservoir inflows. However, the possibility of heavy downpours, thunderstorms and strong winds elsewhere in Tamil Nadu means the next few days will require close attention to local weather alerts.
