New Delhi Apr 27 PTI On the precipice of another punishing heatwave spell Delhi is predicted to see a jump of two to three degrees Celsius in the maximum temperature on WednesdayThe Safdarjung Observatory -- Delhis base station -- had recorded a maximum temperature of 408 degrees Celsius on Tuesday It is expected to breach the 42-degree mark on Wednesday and soar to 44 degrees Celsius by Thursday according to the India Meteorological Department IMDThe maximum temperature may even leap to 46 degrees Celsius in parts of Delhi a Met department official saidThe capital had recorded a maximum temperature of 432 degrees Celsius on April 21 2017 The all-time high maximum temperature for the month was 456 degrees Celsius on April 29 1941Northwest India has been recording higher than normal temperatures since March last week with weather experts attributing it to absence of active Western Disturbances over north India and any major system over south IndiaThe region had got some respite last week due to cloudy weather due to the influence of a Western Disturbance over Afghanistan A yellow alert warning of a heatwave spell in the national capital starting April 28 has been issuedThe 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 The IMD said the heatwave could lead to moderate health concerns for vulnerable people -- infants elderly people with chronic diseases -- in affected areas Hence people of these regions should avoid heat exposure wear lightweight light-coloured loose cotton clothes and cover the head by use of cloth hat or umbrella etc it saidThe city has recorded eight heatwave days in April this year the maximum since 11 such days witnessed in the month in 2010Delhi may see a partly cloudy sky light rain and a dust stormwith winds gusting up to 50 kmph on Fridaywhich may provide a temporary respiteFor the plains a heatwave is declared when the maximum temperature is over 40 degrees Celsius and at least 45 notches above normalA severe heatwave is declared if the departure from normal temperature is more than 64 notches according to the IMDThe weather department had earlier said that northwest India and adjoining parts of central India are likely to see more intense and frequent heatwave conditions in AprilIndia recorded its warmest March in 122 years with a severe heatwave scorching large swathes of the country during the month Parts of the country are also seeing wheat yields drop by up to 35 percent due to the unseasonal heatPTI GVS DV DV