Summer doesn't arrive officially until the solstice at 7:29 Monday morning. But forecasters say the summer's first weeklong stretch of 90-degree heat and high humidity is set to begin this weekend.
And that has spurred Baltimore health authorities to roll out this summer's plans to provide heat relief for the city's most vulnerable residents.
"High temperatures can be lethal, especially for our most isolated, vulnerable residents," said Robert Maloney, director of the city's Office of Emergency Management. "We need everyone to do their part. Be safe in the heat, look out for your neighbors and call 311 if you're concerned about a neighbor's well-being."
The National Weather Service said heat and humidity levels will climb Saturday as high pressure moves off the coast and draws warm, moist air up from the Gulf of Mexico.
Daytime highs are expected to be near 90 degrees Saturday and Sunday, jumping to 93 at BWI-Marshall Airport by Monday. The heat will persist through at least Thursday.
Olivia Farrow, Baltimore's interim health commissioner, is a Buffalo native. "To me, it's hot every day in Maryland," she said.
But when earlier forecasts calling for a high Sunday of 96 degrees downtown were scaled back to 91 or 92 degrees, that reduced the chance that Sunday would become the summer's first Code Red day.
But city agencies are ready, she said.
A Code Red declaration would authorize city agencies to open and staff 11 cooling centers, located in buildings across the city. Residents can also go to local recreation centers to find air conditioning and cold water.
Seniors who have pre-enrolled will have access to the CARE Taxi Card Program for transportation to cooling centers. To enroll, call 410-664-0700. Baltimore Homeless Services will provide bottled water to homeless people on the streets and at designated locations.
"We have people throughout city government, in the field, in contact with people," Farrow said. Ordinary citizens have a role, too. "We're trying to let people know they should be looking out for the elderly in the neighborhood who are living alone, who don't have family."
Extended heat waves and power outages would trigger the opening of additional cooling centers, distribution of fans and ice, and efforts by outreach teams to check on vulnerable residents.
In 2005 and 2006, before Baltimore launched its summertime Code Red Heat Alert program, 35 city residents died of heat-related causes.
In the three summers since, the city has recorded six heat-related deaths. There were none in 2009, Farrow said. "We think we're making a difference."