Update: There's a severe thunderstorm warning until 7 p.m. for parts of Arundel, Howard and Baltimore counties. The excessive heat warning was cancelled after storms rolled through the area.
Friday is forecast to bring one last full day of a heat wave before a cold front brings relief Saturday afternoon, with highs again in the mid- to upper-90s and heat indices up to 110 degrees.
The National Weather Service forecasts a high of 98 degrees in downtown Baltimore, with dew points in the mid-70s making it feel about 10 degrees hotter. An excessive heat warning is in effect for Baltimore City and southern Baltimore County from noon to 8 p.m.
A heat advisory is in effect for the rest of the Baltimore area for the same period. Health officials cautioned of a heightened risk of heat-related illnesses like heat exhaustion and heat stroke and advised residents to drink plenty of water and avoid prolonged periods in the sun.
As of noon, it was 94 degrees with a heat index of 104 degrees at Baltimore-Washington International Thurgood Marshall Airport. It was 97 degrees with a heat index of 109 degrees at the Inner Harbor.
Storms are possible in the afternoon and evening hours.
More heat is expected Saturday. Baltimore health officials have extended a "Code Red" heat alert through Saturday, keeping cooling centers open with free access to air conditioning and water.
Highs Saturday are again forecast in the mid- to upper-90s, with storms more likely as a cold front approaches to end the heat wave. The weather service estimates about a 60 percent chance of storms, most likely in the afternoon or evening hours.
Behind the front, lower temperatures and humidity await. Highs are forecast in the mid-80s Sunday into early next week, with dew points relatively more comfortable in the mid-60s.