Delhi reeled under intense heat on Monday, with the maximum temperature climbing to nearly 43 degrees Celsius in several parts of the city as a sweeping heat spell gripped large parts of northwest and central India.Delhi weather update on May 18, 2026: Temperatures may touch 45°C in parts of Delhi, IMD issues heatwave alertThe India Meteorological Department (IMD) said temperatures are expected to rise further over the next two days, with isolated pockets in the capital city likely to touch 45°C. The weather department has issued a yellow alert for heatwave conditions on Tuesday and Wednesday.According to the IMD forecast, the maximum temperature is expected to remain between 43°C and 45°C, while the minimum temperature is likely to hover around 26.3°C today.The department also forecast mainly clear skies and strong surface winds during the day. “Mainly clear sky. Sustained strong surface winds speed reaching 20-30 kmph occasionally gusting to 40 kmph during the day,” the weather department added.What qualifies as a heatwaveUnder IMD criteria, a heatwave is declared when the maximum temperature crosses 40°C and remains at least 4.5°C above normal. A heatwave is also declared if the temperature touches 45°C or more, irrespective of how far it is above normal.A “severe” heatwave is declared when the departure from normal temperature is 6.5°C or more.The IMD declares a heatwave only if such conditions are recorded at a minimum of two stations within a meteorological subdivision for two consecutive days. The formal declaration is issued on the second day.Similar heatwave conditions are likely to persist across large parts of northwest and central India over the coming days, the weather department said.Delhi temprature forecastTomorrow, on Tuesday, May 19, 2026, Delhi is predicted to experience a minimum and maximum temperature of 36.67 °C and 45.69 °C, respectively. Tomorrow humidity levels will be at 7%.With temperatures ranging between 30.05 °C and 45.63 °C, prepare for a hot day and plan outdoor activities accordingly. If you are sensitive to heat, take note of the weather forecast and consider appropriate attire and activities suitable for the prevailing weather.The AQI in Delhi today stands at 84.0, indicating fine air quality in the city. People with respiratory issues should be cautious, especially while planning outdoor activities. However, others can engage in regular outdoor activities. Being aware of the AQI helps one make informed decisions regarding one's overall well-being while planning the day’s activities.Weather and AQI predictions in Delhi for next 7 days:Weather in other cities on May 18, 2026