The Indian Meteorological Department (IMD) has issued a heat wave alert for several districts of Haryana from May 18 onwards.Besides, there will be a gradual rise in maximum temperature by about four to five degrees Celsius during the next four days in the state.The heat wave alert is from May 18 to May 22. Most stations in Haryana are likely to report temperatures above 40 degrees Celsius in the coming days.“The winds blowing from western Rajasthan are the reason for heat waves in Haryana, Punjab, and Western Uttar Pradesh. There will be a noticeable rise in both daytime and nighttime temperatures. Many stations of Haryana have already started hitting max temperatures close to 40 degrees Celsius or above,” said Director, IMD, Chandigarh, Surender Paul.For plains, heat wave conditions are characterised by a maximum temperature exceeding 40 degrees Celsius, being 4.5 to 6.4 degrees Celsius above normal, or exceeding 45 degrees Celsius.According to the IMD, there is a risk of heat-illness symptoms in people who are either exposed to the sun for prolonged periods or engaged in heavy work.Also, there is a high health concern for vulnerable people, e.g., infants, the elderly and people with chronic diseases.