The heat index in the Bethesda area could reach 106 degrees this week, and Montgomery County health and emergency management officials are warning residents that Wednesday, July 15, is expected to be the most dangerous day.

The National Weather Service issued a Heat Advisory for Montgomery County from 11 a.m. to 8 p.m. on Wednesday, with "feels like" temperatures expected to hit 105 degrees. The dangerous heat is forecast to continue through Friday, July 17, with heat index values potentially climbing to 106 degrees at points during the stretch.

County officials said the combination of high heat and humidity increases the risk of heat-related illness, particularly for infants and children under 4, adults 65 and older, people who are ill or on certain medications, those who are overweight and outdoor workers in construction, landscaping and kitchens.

What to do

Montgomery County recommends residents avoid strenuous outdoor activity during the hottest hours. If outdoor work or exercise is necessary, the coolest window is before 9 a.m.

Electric fans alone may not prevent heat illness when temperatures reach the high 90s, according to county guidance. A cool shower or bath, or moving to an air-conditioned space, is more effective.

County libraries, senior centers, and recreation centers are open as cooling locations. Residents can find specific locations through the county's Office of Emergency Management at montgomerycountymd.gov.

Parked cars and pets

County officials warned that the temperature inside a parked car can exceed 130 degrees in only a few minutes, even with a window cracked. Residents should never leave people or pets unattended in vehicles. Montgomery County's Office of Animal Services said Executive Regulation 17-17, which covers anti-cruelty conditions for dogs and other pets, will be enforced during the heat wave.

Worker protections

Under Maryland law, employers must give workers at least 15 minutes of rest every hour when the heat index reaches 100 degrees. Workers exposed to temperatures of 80 degrees or above have the legal right to cool drinking water, shade, regular rest breaks, heat safety training and a workplace heat safety plan. Workers can report unsafe conditions anonymously through the county's "Be Cool, Montgomery" campaign at montgomerycountymd.gov/BeCool.

Know the signs

Heat stroke is a medical emergency. Symptoms include body temperature above 103 degrees, hot red skin, confusion, loss of consciousness, and rapid breathing. Call 911 immediately and begin cooling the person while waiting for responders.

Heat exhaustion symptoms include heavy sweating, dizziness, headache, nausea, weakness and cool clammy skin. Move to a cooler location, loosen clothing and drink water.

Residents can sign up for Alert Montgomery to receive real-time heat emergency notifications from the county.