The ongoing spell of heatwave in Delhi is likely to intensify with the maximum temperature predicted to touch the 40-degree mark on Wednesday and soar to 43 degrees Celsius by Saturday, the IMD said.

According to the India Meteorological Department (IMD), no relief is in sight for at least a week.

The Safdarjung Observatory, considered the official marker for the city, had recorded a maximum temperature of 39.6 degrees Celsius last Wednesday, the highest this season so far.

Parts of the national capital have been reeling under a heatwave since March last week with their maximum temperature hovering above 40 degrees Celsius.

IMD officials said a prolonged dry spell has led to "severe" hot weather conditions in northwest India.

"The heatwave spell likely is to continue over most parts of Northwest India and Madhya Pradesh during the next five days."

For the plains, a "heatwave" 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 more than 6.4 notches, according to the IMD.

Experts have attributed the hot weather to the lack of rainfall due to dry westerly winds. Delhi recorded nil rainfall in March -- for the first time since 2018. Usually, it gets 15.9 mm of rainfall in the month on average.

India recorded its warmest March in 122 years with a severe heatwave scorching large swathes of the country during the month.

The weather department attributed the unusual heat to the lack of rainfall due to the absence of active western disturbances over north India and any major system over south India.

The country as a whole recorded a rainfall of 8.9 mm, which was 71 per cent less than its long period average rainfall of 30.4 mm. It was also the third-lowest precipitation in March since 1901 after 7.2 mm in 1909 and 8.7 mm in 1908.

"Over the country as a whole, the average maximum temperature (33.10 degrees Celsius) recorded in March 2022 is the highest ever in the last 122 years," the IMD said.

In March 2010, the country had recorded a maximum temperature of 33.09 degrees Celsius.