Tips from Weather.gov
Keep Your Cool in Hot Weather (CDC)
HEAT.gov National Integrated Heat Health Information System

The following groups are particularly vulnerable to heat...

• 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 pre existing diseases, take certain medications, are living alone or with limited mobility who are exposed to extreme heat can experience multiple adverse effects.
• People with chronic medical conditions are more likely to have a serious health problem 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.