Delhi experienced its first heatwave of the season on Monday as temperatures soared to 40.2 degrees Celsius, according to the India Meteorological Department (IMD). In response, the IMD extended the yellow alert in the national capital for the next two days.

Other weather stations across the city also reported scorching conditions, with Ridge and Ayanagar registering maximum temperatures of 41 degrees Celsius. Meanwhile, Palam and Lodhi Road recorded highs close to 39 degrees Celsius, the IMD said.

Heatwave conditions to continue until April 9
The capital is currently under a yellow alert, which will remain in place for the next two days, a weather department official said.

In IMD's colour code, a yellow alert stands for "Be Aware" and advises people to avoid heat exposure, wear lightweight, light-coloured, loose cotton clothes, and cover their heads with a cloth, hat or umbrella.

"Three stations -- Safdarjung, Ridge and Ayanagar -- met the heatwave criteria today, marking the first day of heatwave conditions this season.

"These conditions are likely to continue until April 9. From April 10 onwards, a drop in temperature is expected over Northwest India, including Delhi," the IMD said in a statement.

Temperature touches 40 degrees Celsius during second half of April
According to IMD data, Delhi typically reaches the 40-degree Celsius mark in the latter half of April. However, this year, the capital has hit that threshold in the first half of the month—an early spike similar to what occurred in 2022.

In 2022, Delhi experienced its first heatwave on April 8, with temperatures soaring to 41.6 degrees Celsius. In contrast, no heatwave was recorded in April during 2023 and 2024. Still, the 40-degree mark was touched on April 15 in 2023 and April 26 in 2024.

As per the IMD’s criteria, a heatwave is declared when the maximum temperature reaches at least 40 degrees Celsius in the plains or 30 degrees Celsius in the hills, or when the temperature is 4.5 to 6.4 degrees Celsius above the normal range.

Weather likely to change after April 10
According to Mahesh Palawat from private forecaster Skymet Weather Services, a change in weather is likely after April 10 when the sky will turn cloudy and the temperature will drop due to a western disturbance over North India.

The humidity level in the capital on Monday fluctuated between 45 per cent and 25 per cent during the day, the IMD said.

For Tuesday, the weather office has forecast clear sky with heatwave conditions. The maximum temperature is expected to be around 41 degrees Celsius, and the minimum around 22 degrees Celsius.

The Air Quality Index (AQI) in the capital continued in the 'poor' category on Monday with a reading of 261 at 4 pm, as per the Central Pollution Control Board (CPCB).

An AQI between 0 and 50 is considered 'good', 51 to 100 'satisfactory', 101 to 200 'moderate', 201 to 300 'poor', 301 to 400 'very poor', and 401 to 500 'severe'.