Chennai: Has the city’s fiercest month of May begun to mellow, or is peak summer simply shifting to June? With May halfway through, the city’s Nungambakkam and Meenambakkam observatories are recording near-normal temperatures, thanks to the timely seabreeze.The increased humidity though has made the weather uncomfortable. But the temperatures has not breached 40 degrees so far, as the highest day temperatures recorded are 39°C in Nungambakkam and 39.4°C in Meenambakkam. Rainfall has also made surprise appearances, bringing nearly 3 cm in Nungambakkam and 1 cm in Meenambakkam, offering some relief. Experts say while in the recent years, June may have been as intense as May but factors like wind patterns and the onset of the southwest monsoon largely determine the city’s summer trajectory.Data from the Nungambakkam observatory, which covers the city’s core areas, shows that in recent years, June has sometimes surpassed May in heat. In 2022 and 2023, June recorded the highest maximum temperatures — 40.1°C on June 3, 2022, and 42.3°C on June 7, 2023 — while May’s peaks were lower, at 39.8°C and 41.8°C respectively. But in 2024, May reclaimed its status as the hottest month of the year. The average maximum temperatures for May and June are 37.3°C and 37.2°C respectively.While May remains city’s climatological peak summer month, meteorologists now say June is just as intense, and at times even hotter. Former IMD Deputy Director General Y E A Raj said that day temperatures breach 40°C in May when dry northwesterly winds from inland dominate. In June, extreme heat usually follows strong southwesterly winds that block the seabreeze or a delayed monsoon onset, or absence of cloud cover over the city.For instance, during the 2023 El Nino, June was hotter than May as the southwest monsoon arrived late.“In the last two or three years, June has been hotter than May. So far this month, we’ve escaped hotter days because seabreeze is arriving early and controlling the day temperatures,” Raj said. However, in nine of the last 10 years, May recorded its highest maximum temperature during the second half of the month. So, is the worst yet to come?Weather blogger Pradeep John pointed out that after 2004, 2018, and 2022, May 2025 might also pass without breaching the 40°C mark. There are also several rain spells likely over the city and suburbs for the rest of May. “Weather models show possible rain activity after May 18,” he said. “This May will be unique. The monsoon onset is expected to be early and strong, with more rainfall.”The IMD has forecast that maximum temperatures may rise 2-3°C above normal in isolated pockets of Tamil Nadu, Puducherry, and Karaikal on May 16. Combined with high humidity, this could lead to discomfort in some areas. “On Friday, the city and suburbs may see light rainfall in some areas,” the IMD bulletin said. “Skies will be partly cloudy, with maximum and minimum temperatures around 37°C and 29°C.”