Heat dome to drive temperatures to triple digits this week

A prolonged heat wave will drive temperatures dangerously high in Maryland ahead of the Fourth of July weekend.

A hot air mass, often referred to as a heat dome, has settled over portions of the U.S. and is driving eastward, according to the National Weather Service, with temperatures expected to reach triple digits starting Wednesday.

High humidity could make the weather feel even hotter, with a heat index as high as 115, according to the Weather Prediction Center.

Temperatures will hover in the mid- to upper 90s across Maryland on Wednesday, and highs will climb to 100 in the Baltimore region. Thursday, Friday and the Fourth of July holiday are expected to be the hottest days of the week, said Kevin Rodriguez, a meteorologist for the National Weather Service’s Baltimore/Washington office. Highs will be around 103 those days.

Parts of Allegany County were already under a heat advisory Tuesday, with weather officials warning of heat index values of up to 102 degrees. From Thursday to Saturday, Caroline, Kent, Queen Anne’s and Talbot counties will be under an extreme heat watch when heat index values are expected to reach up to 110 degrees.

The forecast for the week is mainly clear skies, with a 20% chance of rain in the evenings during the weekend.

Stay safe

Extreme heat is the deadliest type of weather, and Maryland has already recorded two heat-related deaths in 2026. Baltimore City Health Commissioner Dr. Michelle Taylor issued this year’s first Code Red extreme heat alert in early June.

A Code Red Extreme Heat Alert is issued when the heat index — which accounts for both air temperature and relative humidity — reaches or exceeds 105 degrees. City outdoor pools will have three two-hour open swimming sessions so more residents can cool off safely during Code Red days. Cooling centers across the city will also be available for residents seeking respite from the heat.

Officials encourage people to build an emergency kit, plan for possible power outages, check fans and air conditioners, and gather food, water and medicine ahead of extreme heat.

During the heat, Marylanders should limit their time outside, Rodriguez said. It’s best to avoid outdoor activities during the hottest part of the day and instead go outside early in the morning or wait until the evening, he said. Officials also warned against leaving children and pets in hot cars.

People should also monitor themselves for any warning signs of heat exhaustion or heat stroke, including muscle pain, headache, vomiting, rapid shallow breathing, nausea, extreme weakness and disorientation. Make sure to drink plenty of water and wear lightweight and loose clothing.

Banner reporter Darreonna Davis contributed to this report.