The yellow alert for heatwave and warm nights that the India Meteorological Department (IMD) had originally sounded from Tuesday has been advanced by a full day — kicking in from Monday itself across Chandigarh, Punjab and Haryana — and will now remain in force through Friday.The warning comes as IMD forecasts a further gradual rise in maximum temperature of 3 to 4°C over the next five days, threatening to push Chandigarh’s daytime high to 41°C by Thursday.Monday stayed dry across Chandigarh, Punjab and Haryana. Even as the day’s maximum in Chandigarh dipped marginally by 1.2°C from Sunday to settle at 38.1°C, it remained a firm 2.8°C above normal. Night temperatures fell more sharply — slipping 2.2°C notches from Saturday night to record 18.6°C, sitting 2.7°C below normal — giving the Tricity a deceptively cool overnight reprieve that IMD warns will not last much longer.Relative humidity ranged between 73 percent in the morning and a very dry 19 percent by afternoon — one of the sharpest humidity drops recorded this season, reflecting the increasingly arid and heat-stressed air mass settling over the region.Chandigarh’s seasonal rainfall since March 1 stands unchanged at 73.4 mm — 149.7 per cent above the seasonal normal.Heatwave grips Punjab, HaryanaHeatwave conditions were formally recorded at Rohtak at 42.3°C and Karnal at 40.7°C on Monday, with warm night conditions also reported at Narnaul and Rohtak in Haryana. Maximum temperatures across Haryana are running appreciably above normal with departures in the range of 3 to 5°C.On Monday, Narnaul topped Haryana at 42°C followed by Rohtak at 41.6°C, Sirsa at 40.6°C, Gurugram at 40.5°C and Hisar at 39.6°C. The lowest minimum in Haryana on Monday was 19.4°C in Sirsa.In Punjab, heatwave conditions were recorded at Ludhiana at 40°C on Monday, with Bathinda topping the state at 41.3°C, followed by Patiala at 39.8°C, Ludhiana at 39.4°C and Chandigarh at 38.1°C. Maximum temperatures across Punjab are appreciably above normal with departures of 3 to 4.5°C. The lowest minimum in Punjab on Monday was recorded at Hoshiarpur at 16.4°C.5-day Tricity forecast: Heat builds relentlesslyTuesday and Wednesday will be mainly clear and partly cloudy, respectively, with the maximum climbing from 38 to 39°C and the minimum rising from 21 to 21°C. Thursday will see partly cloudy skies with the maximum touching 40°C and the minimum at 22°C.The peak arrives on Friday with mainly clear skies and a maximum of 41°C — the season’s highest forecast so far for the Tricity — and a minimum of 23°C, as nights too begin to warm measurably. Saturday holds at 40°C maximum and 23°C minimum under mainly clear skies. The heatwave alert for Chandigarh specifically covers Tuesday through Friday.IMD issues heatwave advisory: What you must doYellow Alert: Heat wave at isolated places; moderate health concern for vulnerable groupsFor the general public: Avoid prolonged exposure to the sun, especially during peak afternoon hours. Drink adequate water and stay hydrated. Wear lightweight, light-coloured, loose cotton clothes. Cover your head with a cloth, hat or umbrella when stepping out.For farmers: To reduce heat stress on crops, carry out irrigation in the evening or early morning hours only.What is yellow alertA yellow alert indicates heat is tolerable for the general public but poses moderate health risk for vulnerable groups, including infants, the elderly and people with chronic diseases.