‘Orange alert’ in place, Delhi may get rain today, says IMD

Delhi’s relative humidity levels oscillated between 41 and 77 percent respectively on Wednesday, but the maximum temperature came down at most stations across the city.

Delhi continued to suffer on account of high temperature and high humidity on Wednesday, with Delhi’s maximum temperature recorded at 40.9 degrees Celsius – 0.6 degrees lower than Tuesday’s high, but still four notches above normal for this time of the year. Delhi’s heat index (HI) or real feel, which accounts for high humidity levels with the air temperature, was calculated at 51 degrees Celsius on Wednesday, two degrees lower than a season high of 53 degrees Celsius, which was recorded on Tuesday. Delhi is expected to see relief from this hot and humid spell from Thursday onwards, with the India Meteorological Department (IMD) forecasting light showers to occur on Wednesday night, while light to moderate showers and gusty winds of 30-40 km/hr will be seen across the capital on Thursday during the day, taking the maximum temperature down to around 34 degrees Celsius.

The IMD currently has an ‘orange’ alert in place for Thursday, owing to chances of light to moderate showers, as well as wind speeds touching 40 km/hr during the day. (HT File Photo)

Delhi’s relative humidity levels oscillated between 41 and 77 percent respectively during the day, but the maximum temperature came down at most stations across the city. While on Tuesday, the highest maximum across the city was 44.2 degrees at Najafgarh, on Wednesday, Delhi’s hottest location was Jafarpur, with a high of 42.5 degrees.

IMD data at 2:30 pm at Safdarjung, representation of Delhi’s weather, showed the air temperature of 40.4 degrees and a relative humidity of 43 percent made the heat index (HI) climb to 51 degrees Celsius. Delhi’s wet-bulb temperature meanwhile came out at 31.89 degrees. These were around 53 degrees and 33.7 degrees Celsius respectively on Tuesday.

The maximum in Delhi is expected to drop down to 34 degrees on Thursday, the minimum will drop to 27 degrees. (HT Illustration)

The heat index (HI) is a function of maximum temperature and humidity, but calculated in the shade. The wet-bulb temperature takes into account maximum temperature, humidity, wind speed, and solar radiation, and is calculated in the sun (under direct sunlight). Both represent how uncomfortable the body feels, owing to high humidity levels.

A wet-bulb temperatures of over 32 degrees makes it difficult for even fit and acclimatised people to work outdoors. At a wet-bulb temperature of 35 degrees, humans can no longer regulate body temperatures, leading to heatstrokes and potential collapse.

As per IMD’s forecast, the southwest monsoon is expected to cover the whole of Delhi over the next 48 hours, with the onset either being declared on Thursday or Friday. The IMD currently has an ‘orange’ alert in place for Thursday, owing to chances of light to moderate showers, as well as wind speeds touching 40 km/hr during the day. On Friday, there is a ‘yellow’ alert, stating light to moderate rainfall may again be recorded.

“On Thursday and Friday, Delhi should see plenty of rainfall, with peak intensity expected on Thursday. By Sunday, the intensity will reduce and only light rainfall is expected, followed by isolated drizzle spells on Monday,” said R.K Jenamani, scientist at IMD. He said moist easterly winds are to be blamed at present to Delhi’s high humidity levels, which will remain high over the coming week, however, Delhi’s maximum will fall, therefore providing a cooling effect.

While the IMD had forecast light rainfall for the city on Wednesday, Delhi was yet to record any rainfall until 10pm on Wednesday night.

In terms of minimum temperature, Delhi had a low of 28.8 degrees Celsius on Wednesday – one degree above normal. While the maximum is expected to drop down to 34 degrees on Thursday, the minimum will drop to 27 degrees.