Monsoon humidity in Hyderabad up 8%, study finds

The heat index during the monsoon now shows a rise from 1.6 degrees Celsius in 2001-2010 to 1.7 degrees Celsius in 2014-2023.

Hyderabad: Hyderabad’s monsoon season is becoming increasingly humid, according to a recent report by the Centre for Science and Environment.

The study, which analyzed data from 2001 to 2023, reveals that humidity levels during the monsoon months (June to August) have risen by 8 per cent compared to the 2001-2010 period.

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This uptick in moisture has led to a slight increase in the heat index, which combines temperature and humidity to indicate how hot it feels.

The heat index during the monsoon now shows a rise from 1.6 degrees Celsius in 2001-2010 to 1.7 degrees Celsius in 2014-2023. This means that despite actual temperatures not rising significantly, the increased humidity makes the air feel warmer and more oppressive.

The report also examines changes during the pre-monsoon period (March to May). It found that this typically dry season has become muggier, with humidity levels increasing by 15 per cent over the past decade.

However, the impact of this added moisture on the heat index is less severe than during the monsoon. The heat index has risen by an average of 1.1 degrees Celsius during the pre-monsoon, up from 0.6 degrees Celsius in the previous decade, indicating a modest increase in perceived temperature.

Despite these increases in humidity, both pre-monsoon and monsoon periods have seen a slight cooling trend in actual temperatures.

The study notes that average temperatures have decreased by 0.7 degrees Celsius and 0.5 degrees Celsius during the pre-monsoon and monsoon seasons, respectively, compared to the 2001-2010 average.

However, the thermal distinction between these two seasons is narrowing, with the difference in the heat index shrinking from 3.1 degrees Celsius to 2.9 degrees Celsius over the same periods.

Another key finding is the urban heat island effect in Hyderabad, where the city’s core remains warmer at night compared to its outskirts.

During the day, the city center is actually cooler than its peri-urban areas by about 0.7 degreesCelsius. However, at night, the situation reverses; the urban core retains more heat and is 1.9 degrees Celsius warmer than the surrounding areas.

This phenomenon means that while peri-urban areas cool down by 12.3 degrees Celsius at night, the city center only cools by 9.7 degrees Celsius, retaining 2.6 degrees Celsius more heat.