<p>There was no let-up in the heat wave that has gripped the national capital, with the mercury staying above the 45-degree Celsius mark in many areas on Monday. Weather experts said a fresh western disturbance may bring some relief on the weekend.</p>.<p>At the Safdarjung Observatory, Delhi's base station, the maximum temperature settled at 43.5 degrees Celsius as against 44.2 degrees Celsius on Sunday and 43.9 on Saturday.</p>.<p>The maximum temperature settled at 46.4 degrees, five notches above normal, at Najafgarh, making it the hottest place in the capital.</p>.<p>Sports Complex, Pitampura, and Jafarpur recorded a high of 46.1 degrees Celsius, 45.8 degrees Celsius and 46 degrees Celsius, respectively.</p>.<p>The Met Office has issued a yellow alert, warning of heatwave conditions at isolated places in the capital on Tuesday.</p>.<p>The India Meteorological Department (IMD) uses four colour codes for weather warnings -- green (no action needed), yellow (watch and stay updated), orange (be prepared) and red (take action).</p>.<p>Mahesh Palawat, vice-president (climate change and meteorology), Skymet Weather, attributed the heatwave spell to the lack of strong western disturbances and incessant hot and dry westerly winds.</p>.<p>He said a fresh western disturbance may induce a cyclonic circulation over Punjab and Haryana which would lead to intermittent pre-monsoon activity in Haryana, Punjab, north Rajasthan and west Uttar Pradesh from June 10.</p>.<p>The maximum temperature in the capital may drop to 40-41 degrees Celsius by Friday.</p>.<p>"With the monsoon expected to cover eastern India by June 15, easterly winds will bring in moisture and intensify pre-monsoon activity in northwest India," he said.</p>.<p>A heat wave is declared when the maximum temperature is over 40 degrees Celsius and at least 4.5 notches above normal. A severe heatwave is declared if the departure from normal temperature is by more than 6.4 notches, according to the IMD.</p>.<p>Based on the absolute recorded temperatures, a heatwave is declared when an area logs a maximum temperature of 45 degrees Celsius.</p>.<p>A severe heatwave is declared if the maximum temperature crosses the 47-degree Celsius mark. </p>
<p>There was no let-up in the heat wave that has gripped the national capital, with the mercury staying above the 45-degree Celsius mark in many areas on Monday. Weather experts said a fresh western disturbance may bring some relief on the weekend.</p>.<p>At the Safdarjung Observatory, Delhi's base station, the maximum temperature settled at 43.5 degrees Celsius as against 44.2 degrees Celsius on Sunday and 43.9 on Saturday.</p>.<p>The maximum temperature settled at 46.4 degrees, five notches above normal, at Najafgarh, making it the hottest place in the capital.</p>.<p>Sports Complex, Pitampura, and Jafarpur recorded a high of 46.1 degrees Celsius, 45.8 degrees Celsius and 46 degrees Celsius, respectively.</p>.<p>The Met Office has issued a yellow alert, warning of heatwave conditions at isolated places in the capital on Tuesday.</p>.<p>The India Meteorological Department (IMD) uses four colour codes for weather warnings -- green (no action needed), yellow (watch and stay updated), orange (be prepared) and red (take action).</p>.<p>Mahesh Palawat, vice-president (climate change and meteorology), Skymet Weather, attributed the heatwave spell to the lack of strong western disturbances and incessant hot and dry westerly winds.</p>.<p>He said a fresh western disturbance may induce a cyclonic circulation over Punjab and Haryana which would lead to intermittent pre-monsoon activity in Haryana, Punjab, north Rajasthan and west Uttar Pradesh from June 10.</p>.<p>The maximum temperature in the capital may drop to 40-41 degrees Celsius by Friday.</p>.<p>"With the monsoon expected to cover eastern India by June 15, easterly winds will bring in moisture and intensify pre-monsoon activity in northwest India," he said.</p>.<p>A heat wave is declared when the maximum temperature is over 40 degrees Celsius and at least 4.5 notches above normal. A severe heatwave is declared if the departure from normal temperature is by more than 6.4 notches, according to the IMD.</p>.<p>Based on the absolute recorded temperatures, a heatwave is declared when an area logs a maximum temperature of 45 degrees Celsius.</p>.<p>A severe heatwave is declared if the maximum temperature crosses the 47-degree Celsius mark. </p>