“The maximum temperature over Delhi NCR varied from 45.2 to 49.1 degrees Celsius across different parts of the city. Mungeshpur's 52.9 degrees Celsius is an outlier compared to other stations, potentially due to sensor error or local factors. IMD is examining the data and sensors,” IMD stated later in the evening.
Not familiar with these sites but here are some articles.
Did Delhi Temperature Reach 52.9 Degrees? The Truth Behind City's All-Time High Record - timesnownews.com
Was it really 52.9 degrees in Delhi? IMD says 'not sure' amid surging heat - business-standard.com
Still... I can't even imagine that kind of heat.