After the widespread thunderstorms across the NCR earlier this week, heatwaves have returned to some parts of the region and are likely to worsen over the weekend.
Heatwaves have caused the mercury to breach the 45-degree Celsius mark in parts of the capital on Friday and are likely to get worse on the weekend. At the Safdarjung Observatory, Delhi's base station, the maximum temperature settled at 42.9 degrees Celsius as against 42 degrees Celsius on Thursday and 41.9 degrees Celsius on Wednesday.
The maximum temperature at Mungeshpur (45.5 degrees Celsius) and Pitampura (45.6 degrees Celsius) settled five notches above normal. The automatic weather stations at Sports Complex and Najafgarh recorded a maximum temperature of 45.7 degrees Celsius and 45.6 degrees Celsius. The Met Office has issued a yellow alert, warning of a heatwave at isolated places in the capital on Saturday. The mercury may jump to 44 degrees Celsius at the Safdarjung Observatory, it said.
The IMD uses four-color codes for weather warnings -- green (no action needed), yellow (watch and stay updated), orange (be prepared), and red (take action). 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 shift from normal temperature is more than 6.4 notches, according to the IMD.
Based on absolute recorded temperatures, a heatwave is declared when an area logs a maximum temperature of 45 degrees Celsius. A severe heatwave is declared if the maximum temperature crosses the 47-degree Celsius mark.