Another scorching heat wave will descend upon Delaware over the weekend, bringing dangerously high humidity and feels-like temperatures. 

A First Alert will be in effect from Sunday morning - when the heat wave starts in earnest - and last through Tuesday evening. The humidity will make the already high temperatures feel even more oppressive. 

"It's humid now, but the humidity will only grow worse over the weekend and into next week," NBC10 First Alert Meteorologist Steve Sosna said. 

Temperatures Sunday will be in the low 90s but will feel closer to 95-100. Monday will be even worse, with feels-like temps reaching 100-105 degrees. The hottest time of the day will be from around 10 a.m. to 3-4 p.m., Sosna said.

Why the Heat Is Worse in Urban Area 

[PHI] Why the Heat Is Worse in Urban Areas

Due to the urban heat island effect, in which buildings and concrete retain heat, some of the most oppressive conditions will be felt in urban areas. "It will probably be a good 5-7 degrees warmer in the urban areas, especially at night," Sosna said.

The heat will pose a threat to everyone, so people should remember to stay hydrated (drinking mostly water and keeping alcohol to a minimum), avoid prolonged periods of direct sun exposure and reapply sunscreen every few hours. 

Keeping your body cool will be key. You can take a cool shower or find a pool. If you don't have air conditioning, you can look for a place like a shopping center, library or movie theater that does. People should also leave windows at least slightly cracked to allow air to recirculate inside their homes, Sosna said. 

"It's important to give your body a break because the heat adds extra stress because your body is working harder to cool itself off," Sosna said.

Extra precautions should be taken for young children, the elderly and pets.

The latest heat wave is the fifth of the season and is being caused by heat from the southern part of the U.S. moving north, Sosna said. In Philadelphia, the highest temperature resulting from the heat waves has been 98 degrees, while the highest feels-like temperature has been 110 degrees.