T.N. records highest Southwest monsoon temperatures in the last nine years

The Southwest monsoon is the seasonal weather period associated with monsoon winds and rainfall over India. In Tamil Nadu, the article measures it from June through September. This period matters because its rainfall and temperatures influence farming, water availability, and summer-like heat conditions before the northeast monsoon arrives.

The Regional Meteorological Centre compared Tamil Nadu’s mean temperatures during these four months across different years. It examined both maximum and minimum temperatures across the State’s weather-station network. June rainfall helped hold temperatures down, but the warming strengthened from July onward.

In 2026, the Southwest monsoon period was exceptionally warm. July, August, and September were each warmer than their corresponding months during 2018–25. The article also reports deficient Southwest monsoon rainfall, including a 12% shortfall, while the northeast monsoon was the next important seasonal weather phase for Tamil Nadu.

Tamil Nadu was nearly 1.21°C warmer than its 2018–25 average during the 2026 Southwest monsoon. The State’s mean temperature was 29.45°C between June and September. This is important because the increase was not limited to daytime heat; nighttime temperatures also stayed unusually high.

The mean maximum temperature was 34.25°C, which was 1.40°C above the 2018–25 average. The mean minimum temperature was 24.64°C, or 1.02°C above average. Together, these figures produced the season’s overall mean of 29.45°C.

The warming strengthened after June. Widespread rainfall in June helped keep temperatures under control, but July, August, and September became the warmest corresponding months in the 2018–25 comparison. The article links the rise to overall warming conditions and a strong El Niño, while also reporting a 12% Southwest monsoon rainfall deficit.

The warming was strongest in the later part of the Southwest monsoon. July, August, and September were the warmest months when compared with the same months during 2018–25. This timing matters because June rainfall initially helped moderate temperatures across Tamil Nadu.

The station assessment identified above-normal mean temperatures at Vellore, Puducherry, Palayamkottai, Meenambakkam in Chennai, Kodaikanal, and Tiruttani. These locations were examples of a broader pattern, not isolated exceptions. The weather-station network showed warming across the State.

The mechanism described in the article was persistent heat after the June rains weakened as a moderating influence. Both maximum and minimum temperatures rose above their earlier averages. The mean maximum anomaly reached 1.40°C, while the mean minimum anomaly was 1.02°C. The article attributes the wider warm trend to global warming and says strong El Niño conditions also contributed.

The Regional Weather Forecasting Centre described the season as sustained warming because elevated temperatures continued over several months. It was not merely a collection of isolated hot days in separate places. This distinction matters because persistent heat can affect daily life and natural systems more broadly than short-lived temperature spikes.

Measurements across the State’s weather-station network showed a widespread pattern. The mean maximum temperature was 34.25°C, 1.40°C above the 2018–25 average. The mean minimum temperature was 24.64°C, 1.02°C above average. Both daytime and nighttime conditions therefore contributed to the season’s 29.45°C mean.

The warming strengthened from July through September, after widespread June rainfall had helped control temperatures. Stations including Vellore, Puducherry, Palayamkottai, Meenambakkam, Kodaikanal, and Tiruttani were above normal. The broad, repeated readings led officials to call it a persistent State-wide trend.

Tamil Nadu’s 2026 Southwest monsoon was the warmest in the table. Its mean temperature was 29.45°C, which was 0.72°C higher than the previous highest value, recorded in 2023. This made 2026 a clear jump above the earlier record rather than a marginal change.

The table lists 2023 at 28.73°C, followed by 2019 and 2024 at 28.54°C. The 2025 mean was 28.48°C, while 2018 recorded 28.27°C. The coolest values were 2020 at 27.95°C, 2021 at 27.77°C, and 2022 at 27.63°C.

Thus, 2026 exceeded every earlier year shown. Its mean maximum temperature was 34.25°C, compared with 33.73°C in 2023. Its mean minimum was 24.64°C, compared with 23.72°C in 2023. The article links the longer-term rise to global warming and strong El Niño conditions.

Unusually high temperatures can make outdoor work harder, increase heat stress, and raise risks for dehydration and heat-related illness. When nights also remain warm, people may get less relief from daytime heat. These are established effects of hot weather, although the article does not provide Tamil Nadu-specific health statistics.

A deficient Southwest monsoon can reduce the water available for rain-fed crops, reservoirs, groundwater recharge, and household use. Heat can increase evaporation and crop water demand at the same time. Together, lower rainfall and higher temperatures may pressure agriculture and water supplies, but the article does not quantify crop losses or reservoir changes.

The article reports a 12% rainfall deficit and a 1.21°C temperature anomaly. It also notes that the east and northeast had their driest monsoon since 1901, while the southern peninsula had its fourth-lowest rainfall. These conditions make monitoring water, farming, and health especially important.

El Niño is a periodic warming of central and eastern tropical Pacific waters that changes atmospheric circulation worldwide. For India, it can weaken monsoon rainfall by disrupting the circulation that normally supports seasonal rains. Global warming is the long-term rise in Earth’s average temperature caused mainly by increasing heat-trapping gases. It raises the background temperature, making hot seasons more likely.

The article says a strong El Niño brought rainfall deficit during India’s Southwest monsoon, including Tamil Nadu. It also says global warming was a major factor behind the State’s soaring temperatures. These influences can work together: El Niño can reduce rainfall, while a warmer climate can intensify heat and increase evaporation.

Tamil Nadu’s 2026 mean temperature was 29.45°C, and rainfall ended 12% below normal. The article identifies 2023, 2024, and 2025 as the three warmest years globally. It presents the warming trend as strengthening since 2020, with the northeast monsoon next in focus.