Delhi has recorded four per cent more than the 30-year average of 149.8 mm rainfall this month. (PTI)

Delhi is likely to witness heavy to very heavy rainfall on Thursday and Friday which will lead to a significant decrease in temperatures and humidity levels.

It would be one of the heaviest spells of the monsoon season so far in Delhi, Mahesh Palwat of private weather forecaster Skymet Weather said.

Delhi has recorded 156.5 mm rains from July 1 to July 23, which is four per cent more than the 30-year average of 149.8 mm, officials said.

Overall, it has received 167.7 mm precipitation against the long-term average of 215.3 mm since June 1, when the monsoon season starts, a deficiency of 22 per cent, according to India Meteorological Department (IMD) data.

Delhi recorded 50.2 mm rainfall, the heaviest in the monsoon season this year, on July 22.

"Monsoon is reviving in north India. On and off rains will continue in the Delhi-NCR region till Wednesday. The axis of monsoon trough, which at present runs south of Delhi, will shift northwards leading to fairly widespread rain and thundershower Wednesday onward," Mr Palawat said.

Heavy to very heavy rain is very likely on July 25 and 26, which will reduce the rain deficit in Delhi, he said.

"The rain on Sunday and Monday was patchy. Now, we may witness rain not only in Delhi-NCR but also Haryana, Punjab, West Uttar Pradesh and up to North Madhya Pradesh," Mr Palawat said.

The IMD in a statement said widespread rain or thundershowers will occur over Himachal Pradesh, Uttarakhand, Punjab, Haryana, Chandigarh, Delhi and Uttar Pradesh from July 24 to 27.

It has predicted one or two heavy rain spells on July 25 and 26.

On Tuesday, Delhi recorded a high of 37.6 degrees Celsius and a low of 28.2 degrees Celsius. Humidity levels oscillated between 57 and 92 per cent.

The weatherman has predicted cloudy sky and moderate rain on Wednesday. The maximum and minimum temperatures are likely to hover around 37 and 28 degrees Celsius.