More rain was expected in Delhi on Thursday after the overnight showers improved the air quality to the poor category and the minimum temperature rose four degrees above normal to 12.3°C compared to 7.3°C a day earlier. The mercury was expected to go up to 19°C.

An average air quality index (AQI) of 261 (poor) was recorded at 9am on Thursday compared to 392 (very poor) at 4pm on Wednesday. The AQI was expected to improve to the moderate range on Friday.

Most parts of the city have received moderate rainfall since Wednesday. Safdarjung, which is representative of Delhi’s weather, received 26.5mm of rainfall between 8:30am on Wednesday and Thursday morning. The rain is more than the monthly long-period average (LPA) for February.

The India Metrological Department (IMD) said another spell of drizzle or light rain was expected across Delhi even as the impact of a second western disturbance was likely to weaken in comparison to Wednesday.

There was just a trace rainfall spell last month on January 23. The latest spell of the rain started after 8:30am on January 31, meaning this will be counted for February’s monthly total.

IMD counts rain for a month until 8:30am on its last day. January hence ended with trace rainfall only, which means a 100% rain deficit compared to the LPA of 19.1mm for the month. This also means with the 26.5mm rainfall, February has recorded excess rainfall already, with the monthly average being 21.3mm.

Rainfall in northwest India in January was the second lowest since 1901 even as above-normal rain was expected in the region in a warmer-than-usual February.

There was a 58% rainfall deficiency across the country in January, 91% in northwest India, 67% in east and northeast India, and 29% in central India. Peninsular India recorded a large excess of 133% rainfall.

On January 1, IMD said monthly rainfall for the month in north India would likely be above normal (>122% of the LPA). Monthly rainfall across the country was most likely to be above normal (>118%).

The lack of any strong western disturbances has been attributed to the large deficiency in rainfall in northwest India. There has been a negative phase of the North Atlantic Oscillation, which is linked to fewer and weaker western disturbances in the region. NAO refers to pressure fluctuations over the North Atlantic Ocean.

In January, northwest India experienced five western disturbances. But most were far too north. Only the one between January 28 and 31 was south enough to bring rain and snow to north and northwest India.