The National Weather Service issued an excessive heat watch Sunday for New Castle County.

The excessive heat watch is in effect from Wednesday morning through Saturday evening. Excessive heat watches are issued when conditions are favorable for excessive heat in the next 24 to 72 hours. Dangerously hot conditions with heat index values of 100 to 105 are possible Wednesday through Saturday.

According to the National Weather Service, a prolonged period of excessive heat with high temperatures in the 90s is expected this week. The heat will worsen as the week goes on, peaking late in the week and into the weekend. These early season heat events combined with the prolonged nature of it may cause an increase in heat-related impacts such heat illnesses.

Heat advisory issued for New Castle County

The National Weather Service had already issued a heat advisory for New Castle County. The heat advisory is from 10 a.m. to 10 p.m. Tuesday.

A heat advisory is issued within 12 hours of extreme heat conditions. Typically, the heat index will be above 100 degrees and the nighttime air temperature will not drop below 75 degrees. The heat index on Tuesday is expected to reach 102.

What should people do during extreme heat conditions?

• Drink plenty of fluids.

• Stay in an air-conditioned room.

• Stay out of the sun.

• Check up on relatives and neighbors.

• Take extra precautions when outside.

• Wear lightweight and loose-fitting clothing.

• Try to limit strenuous activities to early morning or evening.

• Take action when you see symptoms of heat exhaustion and heat stroke.

Who is most vulnerable in the heat?

According to the National Weather Service, heat is among the leading weather-related killers. These are the groups most impacted by high temperatures:

• Young children and infants are particularly vulnerable to heat-related illness and death, as their bodies are less able to adapt to heat than are adults.

• Older adults, particularly those with preexisting diseases, take certain medications, are living alone or with limited mobility and are exposed to extreme heat can experience multiple adverse effects.

• People with chronic medical conditions are more likely to have serious health problems during a heat wave than healthy people.

• Pregnant women are also at higher risk. Extreme heat events have been associated with adverse birth outcomes such as low birth weight, preterm birth, and infant mortality, as well as congenital cataracts.

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This article originally appeared on Delaware News Journal: New Castle County under excessive heat watch. Heat wave hits Delaware