"HCMC is getting hotter these days. Both adults and little children in my family are sick," said Nguyen Khoai Em, who’d brought her five-year-old grandchild to the Children’s Hospital 2 in District 1 on Wednesday. The girl suffered high fever, coughing and vomiting.

Between 3,500 and 7,000 children were seen by the Children’s Hospital 2 in the third week of April, said doctor Huynh Minh Thu with the hospital’s Planning Department. Most of them suffered from respiratory and gastrointestinal problems. About 7 percent of the children had to be admitted, she added.

The number of hand, foot and mouth disease patients at the hospital, one of the two largest pediatrics facilities in the city, has surged 47 percent from last month, while the number of patients with digestion conditions has been up 15 percent.

Searing sunlight and high ultraviolet levels are factors that weaken children’s immune system, Thu said. She said high heat leads to dehydration and spoils food more quickly, which correlate with the increase in patients suffering respiratory and gastrointestinal problems.

At the Thong Nhat Hospital in Tan Binh District, 2,500 patients were seen Wednesday, an increase of 1,000 from Monday. Most of the patients seen were the elderly.

"It’s too hot and I’m old, I can’t take it. I’ve been coughing and feeling fatigue these last few days; even the food does not taste good," said Nguyen Thi Nga, 78, who was waiting for her turn to see a doctor.

The Saigon General Hospital in District 1 has received 20 percent plus more patients this month compared to March. Most of them are elderly patients who suffer strokes or problems with respiration, joints and heart, among others, said Nguyen Khac Vui, the hospital’s vice director.

"If someone has high temperature, increased perspiration and/or quick heartbeats... go immediately go to the nearest medical institution for help," Vui said.

HCMC has been hit by a severe heat wave, with temperatures soaring to 34-37 degrees Celsius. But the RealFeel temperature, which indicates how hot it feels outdoors, was around 40 degrees Celsius, or 104 degrees Fahrenheit. The dry season is expected to last at least until mid May.

The ultraviolet index in the city has risen to extreme levels, posing skin cancer threats to people exposed to the sun, according to U.K.-based meteorological services firm Weather Online. The index climbed to a ‘very high’ level of 10 Thursday and is expected to rise to 12 for several days from Friday.

A UV Index of between 0 and 3 is considered ‘low’, and above 11 is deemed ‘extreme,’ with radiation that could burn skin and damage eyes within 30 minutes.