NEW DELHI, May 29 (Reuters) - Delhi recorded an all-time high temperature of 52.9 degrees Celsius (127.22 Fahrenheit) on Wednesday as extreme heat conditions gripped the north and western parts of India, causing students to faint in schools and drinking water taps to dry up.

A heat wave alert has been in place for large parts of India since last week but on Wednesday the temperature in Mungeshpur, a densely packed corner of Delhi, crossed the 50 C mark, the weather office said.

The Indian capital has had temperatures of over 45 C in previous years but never gone as high as 52.9 C.

Streets in Mungeshpur in northwest Delhi were deserted and most shops were shut as people stayed indoors to avoid the searing heat, while residents handed out free cold drinks in Narela after temperatures went up to 49.9 C on Tuesday.

"When we go outside it seems like someone is slapping our faces. It has become difficult to live in Delhi," said resident Akash Nirmal.

India Meteorological Department (IMD) said it is examining the data and sensors to look into Mungeshpur's temperature which was an outlier compared to other stations.

"There is so much heat in Delhi that students are fainting, some are falling sick, some are facing dehydration. The students are facing a lot of trouble in this heat. The fans don't work in our institutions," said Nidhi, a student, who gave only their first name.

An unusual transition from El Nino to La Nina and the lack of winds bringing moisture, has resulted in prolonged heating, leading to record temperatures, Gufran Beig, chair professor at the Indian Institute of Science told Reuters.

El Nino is the warming of Pacific waters that is typically accompanied by drier conditions over the Indian subcontinent while La Nina is characterised by unusually cold temperatures in the Pacific Ocean.

"We suspect that it is all associated with climate change," he told Reuters.

A spot of light rain in other parts of Delhi later on Wednesday brought some respite and weather officials expect the heat to ease later this week over northwest and central India.

India declares a heatwave when the maximum temperature is 4.5 degrees C to 6.4 degrees C higher than usual and a severe heat wave when it is 6.5 degrees C higher than normal or more.